Simultaneons derivatization and flame photometric detection of some elements fkom Groups 8 and 14.

by

Changhong Shi

Submined in pmtialful$lment of the requirements for the degree of Muter of Science

Dalhousie University Halifax, Nova Scotia December, 1997

O Copyright by CHANGHONG SHI, 1997

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TABLE OF CONTENTS

..... ............................................... Table of Contents ... v ... List of Figures ....................... ...... ........................................................................... VIU

List of Tables .............................................................................................................. xiv Abstract ............................................................................................................................. xv List of abbreviations .... ...,. .......................................................................................... xvi ... Acknow ledgments ...... .. ............................................................................................... xviii

CHAPTER 1 . LITERATURE REVIEW

1 . 1 Introduction ............. ... ............................................................................................. 1

1.2 Rame photometric detectors ............................................................................... 2 1.2.1 The Shimadni FPD .......................... ,., ........................................................... 3 1.2.2 Mechanism for the response in the FPD .................................... ... .................... 4

....................................... 1.2.3 New modifications in the FPD .............. .......,., 4 1.2.4 Analytical applications of the FPD ............................................................... 6 1.2.5 Different modes of operation of the FPD ........................................................ 8

......................... 1.3 Methodology of derivatization of metal containing species 8 (1) Vapor generation method ..................................................................................... 9 (2) Derivatization in the aqueous phase ............................................................... I I (3) Derivatization by Grignard reagent .................................................................... 1 1

1.4 Research Objectives ......................................................................................... 12

....................................................... CHAPTER 2 . EXPERIMENTAL 13

CHAPTER 3 . THE BEHAVIOR OF LEAD IN THE SMALL STOICHIOMETRIC FLAME

3.1 Measurement of the lead spectnun ............................................................... 1s ............................................................................. ................ 3.1.1 Introduction ..... 15

3.1.2 Experimentd ................................................................................................... 15 . 3 . t 3 Results and discussion .......................... ... ....................................................... 17

3 . 2 Analytical application of the Ultra-violet band of Pb0 ................... .... . 17 3.2.1 Experimentai ................................................................................................. 17

3.2.2 Results and discussion ..................................................................................... 1 9

3.3 Mechanisms of emissions of Pb and other FPD-responsive ......................................................................................... elements .................... ... -23

3.3.1 Experimental ........................ ..... ................................................................ ..27 ................. 3.3 .2 Results and discussion ................ ...,,.....-...................*.........-..-..- 27

3.4 Derivatization and determination of inorganic lead (II) ......................... -27 3.4.1 Experimentai ............................................................................................... 27 3 .4.2 Results and discussion .................................................................................... -34

CHAPTER 4. SIMULTANEOUS DERIVATIZATION AND DETECTION OF SOME TRANSITION ELEMENTS

4.1 Introduction ............................................................................................................ 40

4.2 Denvatization of transition elements with lithium c yclopentadieny lide ............................................................................................ -4 1

4.3 Results and discussion ..............................

CHAPTER 5 SIMULTANEOUS DERIVATIZATION AND DETECTION OF INORGAMC GERMANIUM, TIN AND LEAD SPECIES WITH AND WITHOUT IRON GROUP ELEMENTS

.......................................................................... ........................... 5.1 Introduction .. 74

................ ...............................................................*......--............ 5 -2 Experimental .:.. -75 5.2.1 Denvatkation of organotin compo~ds with triphenylmagnesium

bromide .......................... .,. ...... ,.,. ................................................................... ..75 5.2.2 Sirnultaneous derivatization and detection of inorganic

germanium (IV), inorganic tin (IV) and inorganic lead (II) species ................ 76

5.2.3 Simuitaneous denvatization and detection of inorganic species containhg germanium (IV), tin (IV), lead (II), iron (II), rutheniun (III) and osmium ......................................... . 6

5.3 Results and discussion ...................... .. .......................... 77

CHAPTER 6. CONCLUSION AND SUGGESTIONS ............. 98

APPENDIX DEFINITIONS FOR SOME SPECIFIC TERMS USED IN THIS THESIS ..................... ioo

REFERENCES .............................................................................................. i o i

LIST OF FIGURES

Fig . 1

Fig . 2

Fig . 3

Fig . 4

Fig . 5

Fig . 6

Fig . 7

Fig . 8

Fig . 9

Simple diagram of the interface between the detector body ............................. ................................................ and the monochrornator ..... 16

................................................. Lead spectrum under stoichiometric condition 18

Calibration curves of tetraethyliead and dodecane obtained using a 385 nm LP filter .................................................................................. 20

Optirnization of the air flow (340 nm interference filter) ......................... .... 21

Optimization of the hydrogen fiow (340 nm interference filter) ...................... 22

Selectivity of Iead against other elements at stoichiometric flame conditions ............................ ,,..... ...................................................... 24

Chromatogram of 2.0 ng tetraethyllead and 2.5 ng tetrabutyltead .................... 26

Chromatograms of 5 ng tetraethyllead with and without chimney .................... 28

......................... Chrornatograrns of 5 ng osmocene with and without chimney 29

. ................... Fig 10 Chromatograms of 0.5 ng ruthenocene with and without chimney 30

. Fig 1 1 Chromatograms of 1 . 0 pg triphenyl bismuth with and without chimney .......... 31

Fig . 12 Chromatograms of 10 ng tris (pentafiuorophenyl) phosphine with and ................................................................................................ without chirnney 32

Fig . 13 Chromatograms concerning the derivatization of inorganic lead (II) ................ 35

Fig . 14 Effect of the pH-value on the derivatization yield of inorganic Iead (II) .......... 36

Fig . 15 Influence of the weight ratio of sodium tetraethylborate to lead on the denvatization yield of inorganic lead 0 .............................................. 37

viii

Fig. 16

Fig. 17

Fig. 18

Fig. 19

Fig. 20

Fig. 21

Fig. 22

Fig. 23

Fig. 24

Fig. 25

Fig. 26

Fig. 27

Caübration cuve of the inorganic lead (II) derivatized by sodium tetraethylborate (5 rnL benzene as the extractant) ........................................... 38

Calibration curve of the derivatization products of inorganic lead (II) by sodium tetraethylborate (1 mL benzene as the extractant) with and without evaporation ... ... ...... . .. . . . . . . . ............... .......... ...................... 39

Chromatograms concerning the derivatization of iron (II) chlonde tetrahydrate by lithium cyclopentadienylide. (A), (B) ........................ 45

Chromatograms conceming the derivatization of iron (II) chloride tetrahydrate by lithium cyciopentadienylide, (C) ................................ 46

Chromatogrm conceming the derivatization of iron 0 chloride tetrahydrate by lithium cyclopentadienylide, @), (E) ......................... 47

Chromatograms conceming the derivatization of iron (II) chlotide tetrahydrate by lithium cyclopentadienylide, (F), (G) ......................... 48

Chromatograms conceming the derivatization of ruthenium (11) chloride hydrate by lithium cyclopentadienylide, (A), (B) ............................... 49

Chromatograms conceming the derivatization of ruthenium (ID) chloride hydrate by lithium cyclopentadienylide, (C). (D) ............................... 50

Chromatograms conceming the derivatization of ruthenium (III) chionde hydrate by lithium cyclopentadienylide, (E), (F) ............................. 51

Chromatograms conceming the derivatization of ruthenium (III) chloride hydrate by lithium cyclopentadienylide, (G) ....................................... 52

Chromatograms concerning the denvatization of osmium containing compound by lithium cyclopentadienylide, (A), (B) ......................................... 53

Chromatograms conceming the derivatization of osmium containing compound by lithium cyclopentadienylide, (C), (D) ....................................... 54

Fig. 28

Fig. 29

Fig. 30

Fig. 3 1

Fig. 32

Fig. 33

Fig. 34

Fig. 35

Fig. 36

Fig. 37

Fig. 38

Fig. 39

Chrornatograms concerning the derivatiiration of osmium containin compoimd by lithium cyclopentadienylide, (E), 0 ........................ ..... ........ S 5

Chromatogram conceming the derivakation of osmium containhg compound by lithium cyclopentadieny lide, (G) ................... ..... ....................=.. -5 6

Chromatograms conceming the denvatization of nickel (II) chloride hexahydrate by lithium cyclopentadieny lide, (A), (B) .................................. .5 7

Chromatograms concerning the derivatization of nickel (11) chloride hexahydrate by lithium cyclopentadieny Ede, (C), @) ..................... .. ......... .5 8

Chtomatograms conceming the derivatization of nickel (II) chloride hexahydrate by lithium cyclopentadienylide, (E), 0 .................................. 59

Chromatograms conceming the derivatization of nickel (II) chloride hexahydrate by lithium cyclopentadienylide, (G) ............................................. -60

Opthkation of the process of the deriv-on of iron (II) chloride tetmhydrate with lithium cyclopentadienylide ... .... ................................... -62

The effect of reagent amount to the yield of derivatization (for imn (II) ....................................................................................... chloride tetrahydrate) 63

The effect of reagent amount to the yield of derivatization (for ................................ rutheniun (III) chloride hydrate) ... ............................... 64

Chromatograms concerning the derivatization of the mixture of iron (TI) chloride tetrahydrate and nickel (II) chloride hexahydrate by sodium cyclopentadienylide, (A), (B) .................... .. .................................................. ..65

Chromatograms conceming the derivatization of the of ùon (II) chlonde tetrahydrate and nickel (II) chloride hexahydrate by sodium cyclopentaâienylide, (C), (D) ...................... ... ............................................ -66

Chromatograms conceming the derivatization of the mixture of iron (Il) chioride tetrahydrate and nickel (II) chlonde hexahydrate by sodium cl0 pentadieny lide, (E), (F) ............................................................................... .67

Fig. 40 Chromatograms conceming the derivatkation of the mumire

FigA 1

Fig.42

Fig.43

Fig. 44

Fig. 45

Fig. 46

Fig. 47

Fig. 48

Fig. 49

of iron (II) chloride tetrahydrate, ruthenium (III) chloride hydrate and osmium containing compound by sodium cy clopentadienylide, (A), (B) .................................-..... ...........4

Chromatograms conceming the derivatkation of the mixture of iron (II) chionde tetrahydrate, ruthenitun (III) chloride hydrate and osmium containing compound by sodium cyclopentadieny lide, (C), @) ..................... ... ........................ ..... .... 70

Chromatograms conceming the denvatization of the mixture of imn (II) chloride tetrahydrate, rutheniun (III) chloride hydrate and osmium containing compound by sodium cyclopentadienylide, (E), (F) ............................................................. 7 1

Chromatograms conceming the derivatkation of the mixture of Uon (II) chloride tetrahydrate, nahenium (m) chioride hydrate and osmium containing compound by

sodium cyclopentadieny lide, (G) ................................... ... .......................... ..72

Cornparison of the chrornatograms of dried THF (distilled through sodium) and untreated commercial THF .......................................................... -73

Chromatograms of (A): phenylmagnesium bromide; (B): triethyltin .......................... chioride; (C): tripropyltin chioride under the same conditions 78

Chromatograms of the derivatized products of @): triethyltin chloride; (E): tripropyltin chlonde with phenylmagnesium bromide ................................ 79

Chromatognuns conceming the derivatization of the mixture of lead (II) nitrate, tin (IV) chioride and germanium (IV) chloride by butyimagnesium chloride, (A), (B) ........................ .,. ............................... ..8 1

Chromatograms conceming the derivatization of the mixture of lead (II) nitrate, tin (IV) chloride and germanium 0 chlonde by butylmagnesium chloride, (C), @) ..... ................. ..................................... .82

Chromatograms conceming the derivatization of the mixture of lead (II) nitrate, tin (IV) chloride and germanium (IV) chloride by butylmagnesium chioride, (E), (F) ................................................................ 83

Fig. 50

Fig. 5 1

Fig. 52

Fig. 53

Fig. 54

Fig. 55

Fig. 56

Fig. 57

Fig. 58

Chromatograms concerning the derivatization of the mixture of lead (II) nitrate, tin chlonde and germanium (IV) chloride

................... ...................**....~........*....... by butyimagnesium chioride, (G) .. -84

Chromatograms concerning the derivatizaton of the mixture of lead (II) nitrate, th 0 chioride and germanium 0 chloride

................................ .................. by buty lmagnesium chloride, (H), O ...... -85

Cbromatograms concerning the derivatization of the mixture of l d (II) nitrate, tin 0 chloride and germanium (IV) chloride by butylrnagnesium chloride, (J). .................. ........ ...................O.................... -86

Chromatograms of the mixture of 2 ng tetrabutylgermanium, tetrabutyltin and 20 ng tetrabutyllead, (A), (B) ................................................. 87

Chromatograms of the mixture of 2 ng ferrocene, 500 pg ruthenocene ........................................................ and 3.5 ng osmocene ................................. 89

Chromatograms conceming the derivatization of the mixture of lead (II) nitrate, tin (IV) chloride and germanium 0 chloride, iron (II) chloride tetrahydrate, rutheniun (m) chioride hydrate and osmium containing compound by butyhagnesium chloride and lithium cyclopentadieny lide, (A), (B) ............................................................. -92

Chromatograms concerning the derivatization of the mixture of lead (II) nitrate, tin (IV) chloride and germanium 0 chlonde, iron (II) chioride tetrahydrate, ruthenium 0 chloride hydrate and osmium containhg compound by butyimagnesium chloride and lithium cyclopentadienylide, (C), @) ............................................................. ..94

Chromatograms conceming the derivatizttion of the mixture of lead (II) nitrate, tin (IV) chlonde and germanium (iV) chloride, iron (II) chloride tetrahydrate, nitheniun (III) chlonde hydrate and osmium containing compound by butyimagnesiurn chloride and

................... .............*......*...............*. lithium cyclopentadieny lide, (E), (F) ... -95

Chtomatograms concerning the derivatization of the mixture of lead (II) nitrate, tin (IV) chioride and germanium (IV) chlonde, iron (II) chioride tetrahydrate, rutheniun (III) chioride hydrate and osmium containhg compound by butyimagnesium chloride and

xii

lithium cyclopentadienylide, (G), (H) ................ ... ......--.... .-..... ..... ... .... 4

Fig. 59 Calibration curves for the simultaneous detection of germanium chloride, tin (IV) chlonde, leaù (II) nitrate, iron (II) chioride tetrahydrate, nithenhm (II) chloride hydrate and osmium containing compound ................. 97

xiii

LIST OF TABLES

Table 1. Seiectivity between lead and other elements (mole PWmole element) ........ ...... 25

xiv

Abstract

A number of environmentally interesting cornpoumis, including lead containing

species, were investigated in an attempt to improve both the sensitivity and selectivity of

their analysis. By usïng GC-FPD (Gas chromatograghy-flme photometric detection) and

a 340 nm interference filter, the selectivity of lead determination against carbon was

increased four times compared with that obtained under reguiar conditions. Some work

was done with GC-FPD to determine inorganic lead (II) species with high sensitivity.

The detection limit of lead (II) was 1 ppb (part per billion) when extraction was carried

out &er the derivhtion of lead 0 nitrate. Aiso, elements in Group 8 ( iron,

rutbenium and osmium) were successfully derivatized with lithium cyclopentadienylide

and detected simultaneousIy. Nickel (TI') was d e n v a with sodium

cyclopentadienylide and detected with GC-FPD. Similar work was completed with some

elements of Group 14 (germanium, tin and lead). Finally, muMelement detection of six

inorganic species (of iron, mthenium, osmium, germanium, tin, and lead) were realized

by using GC-FPD with a "conventional-type flame" after being denvatized .

simultaneously with butylmagnesium chloride and lithium cyclopentadienylide.

ABBREVIATIONS AND SYMBOLS"

AED

AFID

AW

CE

CH1

CH2

CONDAC

ECD

ELCD

FID

FPD

HPLC

ICP

IR

LP

MIP-AED

MS

-atomic emission detector (1)

-alkali flame ionization detector (1)

-acid washed (13)

-capillary electrophoresis (8)

-the first channel(l7)

-the second chamel (1 7)

-conditional access mode (7)

-electroon capture detector (1)

-electrolytic conductivity detector (1)

-flame ionhtion detector (1)

-flame photometric detector (1)

-hi& pressure liquid chromatography (8)

4nductively coupled plasma (2)

-uinared spectrometer (1)

-long pass (2)

-microwave-induced plasma-atomic emission detector (3)

-mas spectrometer (1)

PFPD

P M

RFD

P P

TBGe

TBL

TBSn

TCD

TEL

THF

-puise £lame photometric detector (5)

-photomultipIier tube (2)

-reactive flow detector (5)

-sipnaVnoise @eak to peak) (19)

-tetrabutylgemanium (82)

-tetrabuty llead (1 9)

-tetrabutyltin (53)

-thermal conductivity detector (1)

-tetraethyllead (1 5)

-tetrahydrofùran (4 1 )

a The number in parenthesis indicates the page number where the abbreviation fim

appears.

Acknowledgments

I deeply appreciate the excellent puidance of my supervisor, Dr. Walter A. Aue.

1 would also iike to thank Jiirgen Müller for the glas blowing, Br& Millier for

solving electronic problems, Cecil. G. Eisener, Rick Conrad and Ross Shom for their

machining expertise.

My colleagues: Kelvin Thurbide, Taghi Khayamian, especially Nancy Lowery,

Hameraj Singh and Zhongping Lin are deserved my acknowledgments for their kind

assistance.

Special thanks are given to my supervisory committee: Dr. Amares Chatt,

Dr. Robert D. Guy and Dr. Roderick Wasylishen for reading and correcting this thesis.

Finally, 1 extend my gratitude to Dalhousie University for h c i a l support.

CHAPTER 1.

LITERATURE REVIEW

1.1 Introduction

Gas chromatography (GC) has long k e n recognhd as an excellent method with

both high selectivity and sensitivity for the resolution of complex mixtures. There have

been many different kinds of GC detectors developed so that the determination of a wide

variety of substances is feasible. This gives GC certain advantages over some other

analytical methods.

There are seven kinds of detectors commonly used : flame ionkation detector

(Fm), t h e d conductivity detector (TCD), electron capture detector (ECD), atomic

emission detector (AED), flame photometric detector (FPD), alkali flame ionization

detector (AFID) and electrolytic conductivity detector (UCD). GC, which provides a

device for good separation, has recently been interfaced with other common anaiytical

methods to fom "hyphenated techniques" . Theoretically, as the sample elution rate in

GC is very fkt, a rapid response of the coupled instrument is necessary. Therefore, both

mass spectrometers (MS) and Fourier transform idkared spectrometers (IR) have been

very successfully wupled with GC. When MS is use& the detection of the d y t e is

based on the different masskharge ratio. However, in IR, the characteristic

" IR spectrum" of the analyte is recorded and both the qualitative and quantitative

information can then be obtained. Other techniques such as GC-AAS (atornic absorption

spectrometry), GC-ICP-MS ( ICP: inductively coupled plasma) have also been

developed. GC-ICP-MS has been very useful when identification of isotopes is required.

1.2 Flame photometric detectors

Brody and Chaney first introduced the flame photometric detector (FPD) for

the detection of some sulfur- and phosphorus-containhg organic compounds by gas

chromatography. These researchers successfully determined the sulfur compounds in

gasoline and phosphonis compounds found in pesticide residues on vegetables. The

essence of the detector used was a "cool" air-hydrogen flame. Cherniluminescent

emission fkom the excited molecular species S2 and H P 0 was observed in the secondary

zone of the flame by photomultiplier tubes (PMT). The sensitivity of the determination

for sulfur and phosphorus was 1 x 1 O-'' g/s and 1 x 10-I2 gls, respectively. The high

sensitivity of this method made an important development in ' b c e d y s i s " .

An advantage of the FPD is its low noise level, which is fundamental in nature.

Generally, a narrow bandpass interference filter is used for a sharp "1ine"or "band", a

long pass (LP) or a shortpass filter is used for a bbcontin~um ". This way, an analyte can

be selectively detemiined without interference fiom hydrocarbon species (either in the

ma& or fiom solvents). FPD detectors are much cheaper and much simpler than other

detectim methods, such as the microwave-induced plasma-atomic emission detector

(MIP-AED), or MS. Meanwhile, the detector is " mgged ". That is, even after fkequent

use, it still has good stability and reproducibility which is necessary for practical

analyticai use.

1.2.1 The Shimadzu FPD

The Shimadzu FPD is similar to the original FPD that has been available for a

long t h e . The bumer consists of two concentric tubes: air flows through the inside tube,

while in the outer tube flows a mixture of hydrogen (flame gas), nitrogen (carrier gas) and

sample vapor fiom the column. These gases r n k just at the tip to form a "diffusion"

flame. If these gases mix before the tip, then it is called a "pre-mDr flamey', which has

been previously s h o w to be " marginally more sensitive, but more difficult to handle,

and hard to remove the waste from the unbumt re~idues"~].

The flame in the flame photometric detector is usually hydrogen nch, i.e., it is a

relatively cool flame, while in the cornmon flame ionization detector, an air-rich,

relatively hotter flame is used. A quartz tube around the bumer acts as a chimney and

prevents outside air fkom inauencing the flame. The light passes through a glas window,

which prevents water vapor and u b m t residues fiom reaching the opticai filter or PMT.

Then, after filtering, the light reaches the PMT. This provides an electronic signal which

is amplified and recorded as a chromatogram. From the change of the emission with

Merent wavelengths, sample spectra can be obtained for qualitative analysis. From

calibration plots, quantitative information c m be acquired. Sometimes, a dual-channel

operation is used, Le., the simultaneous monitoring of two elements c m be done by using

two separate chaanels each with a different optical filter. For example, a 394 nm

intederence filter and a 526 nm interference flter have been used to simultaneously

monitor sulfur and phosphorus.

1 2 3 Mechanism for the response in the FPD

The signal that is recordeci by the PMT in a FPD is mainly due to the

cherniluminesence of the corresponding elements, even though the origin of the active

species may be quite different. The anaiyte molecules get en= fiom the chernical

reaction to fom excited molecules which emit photons while transferring to a lower

energy state or ground state. For exampie, it is weli known that sulfur's signai is caused

byP1

Sulfur containhg cornpounds+ H2S (1)

H2S+H=+HS* +Hz (2)

HS-+H=+H2+S- (3)

S-+s-+M+s,'+M (4)

s2'+s2+hv (5 )

S2+H-+H-+S2*+H2 (6)

S2*+S2+hv (7)

Here, M is a third body.

HPO'+HPO is responsible for the phosphorus emission.

1.23 New modifications in the FPD

Although the original design of the FPD was very useful, there were still a

5 number of drawbacks. ûver t h e , sorne improvernents were made to obtain ideal

detector @ormance. Burgett and Green solved a flame-out problem by reversing the air

and hydrogen gas inlets and premWng the column effluent with the hydrogen stream

Another problem in the FPD was that the response of some anaiytes could be quenched

by hydrocarbons, usually present as solvents. In some cases, the quenching effect was

so high that the FPD's application was totally impossible. Many studies have been made

on the nature of quenching and its mechaaisrn [&'ll. Liu and coworkers proposed a

methoci of evaluating these quenching effects. Among them, the mechanism of sulfur has

been studied with the most detail [10,13,141 . Patterson claimed (lSl that the quenching

problem could be elimiriated by a new dud flame FPD. He used two hydrogen-air flames

to separate the sample decomposition region fiom that of the chemiluminesceat emission

region. A novel type of chemiluminescence-based detector, similar to the FPD in this

respect, has been developed recently [16181. Called a reactive flow detector (RFD), it has a

luminescent column, rather than a flame, which is used for the photometric detection of

the sample. A stable flarne at the top border of the reactive flow can initiate and support

any &-radical reaction. This reaction goes down dong a glas capiilary to a lower

border formed by the nearest stabilizing restriction. Its advantage is that the quenching

by hydrocarbon does not occur, so sometimes this detector is calied a "quenching-free"

FPD.

Further modifications to the FPD were made in the fonn of a pulse flame

photometric detector (PFPD). It has been developed and can be used to determine certain

compounds with high sensitivity ligl.

1.2.4 Andytical applications of the FPD

FPD was f h t used to determine phosphorus and sulfur, which can be analyzed

separately, or simultaneously in dual mode. The Dual-mode allows the phosphodsuhr

ratio to be determined- That provides some qualitative information on the d y t e . Later,

the FPD was found to respond weii to boron. When Sowinski and SufTet utilized a hot

fiame composed of about stoichiometric proportions of hydrogen and oxygen, they

obtained good response fiom boron. The hot flame here, however, produces emission

mainly due to a thermal effect, not cherniluminescence. Chromiurn and organohalogen

compounds could give good FPD response under different conditions . Chrorniurn 12''

nom physiological fluids has been determined using a hot 4 /Air/H2 fiarne with an

detection limit for Cr(tfa)3 (trifluoroacetylacetonate) of 13 pg. Many modified FPDs have

been used for the determination of organohalogen compounds. These analyses were

mainly based on a response produced by a bbsensitizing substance". For example, Brown

and Beroza used a copper-sensitized FPD. The hydrogen and the col- effluent

(containing halogen ) passed through a copper screen, and burned in oxygen admitted

above the screen. This produced haiides which gave a good FPD response. That was an

indirect way to determine chlorine. This type of detector couid also respond

exponentiaily to organobromide and iodide cornpounds, and linearly to some other

compounds. Similariy, indium has good FPD response. Sensitized indium FPD ~ 3 2 4 1 cm

be used for sensitive and selective determination of organohalides (except fluorine)

dependhg on the indium halide emission or atomic indium emission in some cases 12'!

With the use of an optical filter to elirninate hydroxyl bands (about 306 nm),

7

many organometaüic compounds, which usually produce broad emission bands, c m be

detemiined with high sensitivity. Compounds of transition elements have k e n

investigated by various modified FPDs; e.g., Sn and Ge 12-, Se and Te Fe, Ru, Os,

Mn, Ni, Re, Mo and Co have ail been studied in detail by Aue and his research

group P'J31. Two new computer-assisted techniques for operation of the FPD, the

differentid mode and the conditional-access mode (CONDAC), have been established by

the same group. In the former mode lWq, two c b e l s were used. One channel

monitored a wavelength where the d y t e responds weii, and part of the response h m

carbon was also seen; the second channel monitored a wavelength where carbon responds

weil, but response fiom the d y t e element is weak. By the adjustment of the signal

fkom the second chaonel, the contribution fiom carbon response could be made equal.

Then, when the content in one chamel was subtracted fiom the other, the contribution

fIom the carbon response would disappear and the pure signal due to the analyte could be

obtained. This technique is very helpfd in the analysis of those environmental samples

which have cornplex matrices and where peak overlap usually occurs 1361. Using this

method, the authors P61 have successfidly separated coeluting isomers of meta-fluoro-

benzaldehyde and ortho-fluoro-benzy laldehyde. Meanwhile, by this technique, the

selectivity using FPD to determine one element (e-g., a transition element) against carbon

signincantly improved. In the CONDAC mode, the response ratios for two channels

were used. They can be peak area ratio, peak height ratio or peak dope ratios. Using these

two methods, both main-group elements and transition elements were determined.

Finaliy, the FPD not only cm be coupled to GC as a powerfid detector, it has

8

also been recentiy w d as a detector for other andytical techniques, such as high pressure

liquid chromatography (HPLC) r371 and capillary electrophoresis (CE) "I. Taking

advantage of the booming development of electrospray, FPD was used to detect elements

introduced by electrospray into a flame. Some transition elements, Cu, Mn, Ni, etc., have

been detemiined with hi& sensitivity. Using this syne technique, investigation of

proteins and DNA are being perfonned r391.

1.2.5 Different modes of operation of the FPD

Usually, the FPD is operated with a hydrogen-rich fiame. Hydrogen flows can

reach up to several hundred W m i n , whereas a typical air flow is a tenth of this

value The optimum conditions for different elements v q . When the flow rates of

both hydrogen and air decrease, not only the sensitivity of detemination cm be

increased, but aiso the optimum conditions don? ciiffer much with the elements

detemiined 12'. SO in the following work, except where specifically indicated, a srnail,

near stoichiometnc flame is selected. The flow rates are: 16 mL/rnin for hydrogen,

41 mL/min for air and 20 rnL/min for nitrogen (carrier gas).

Methodology of derivatization of metal containing species

GC-FPD methods have special advantage for their hi& sensitivity and good

selectivity (obtained either by suitable filter or specific detector). However, there are

disadvantages. GC can on1 y detemine volatile or some semi-volatile materiais direct1 y.

That greatly limits the usage of GC in practical application.

9 In order to solve the problem, it is necessary to derivatize the non-volatile

materials to more volatile derivatives. Many studies have been done on the derivatization

rnethods related to GC such as silylation and acylatim W. The new methods "in this

field" can be divided into the following different categories: vapor generation,

derivatization in the aqueous phase, and Mgnard derivatization.

(1) Vapor generation method

Vapor generation technique is used to determine trace eIements It provides an

ideal sample introduction method not only for GC, but also for atomic absorption

spectrometry. It has the foliowing advantages: a large sample volume can be used and

yields excellent detection limits. It can separate the analyte nom very complicated

matrices (for example: biological samples, envVomental sampIes ), so the interference of

other non-interesting elements will be greatly decreased. Since gas phase methods me

cleaner, column contamination is less. Frequent, the-consuahg cleaning is eliminated.

The most common way to obtain vapor is hydride generation. Hydride generation was

originally used in atomic absorption spectrometry to detennine As and Se. At one time,

[4 l.421 some metd-acid systems were use& such as SnC1,HCI-KI-Zn and TiC1,-HCCMg .

The most popuiar method of hydride generation at the present time uses tetrahydroborate

(NaBH4) which gives rise to the conesponding volatile hydrides of metals. The reaction

1s:

NaBH4 + 3H20 +HCl+H3B0,+NaC1+4H2 (+E m)+~~,+~2(excess)

E is the analyte of interest.

For example, SnH4 can be obtained by:

NaB& + 3H20 +HCI+H3B03+NaC1+4H2

sn4++ 4 H2-S-+2 H2(excess)

Other elements, such as As, Bi, Ge, Pb, Se, Te, Tl have also been successfUy

determineci [ " - 4q in AAS. The general procedure for the determination is: hyàride

generation, collection or flush of the hydride and then atomization of the hydnde.

Sidarly, this method can be used in a GC system after the derivatkation to form

volatile hydrides. E-Iyd.de generation can be done prior to the column [48 ( prr-column

derivatization). The generated hydrides are then either purged and concentrated by

trapping before separation and detection, or they may be extracteci from the sodium

tetrahydtoborate solution with an organic solvent ( e.g., dichloromethane), which is then

injected ont0 the columa This was w d to detemiine butylhg compounds in naturai

water. Reproducible resdts for naturai water can easily be obtained for ng quantities of

tia Later, the volatile hydride generation was done on the column itself. The

derivatking reagent was piaced just in front of the column with an entrance specialiy

modified to f i t to that purpose. When rnetal-containing solutions were injected, reactions,

similar to those in AAS, will occur. The author [481 codd detect Bu3SnCl in distilled

water at levels of 50 ng/L. Butyltin speciation was done with the help of a temperature

program. The packed column was changed at intervals of several months, and the

denvatizing reagent was changed weekly.

Hydride generation method could be coupled with atomic ernission

spectroscopy (AES) r491. The detection limit for the butyltin determination was

1 ng/l O mL water sarnple. It was found that the addition of ammonium peroxodisulfate

11

enhanced the recovery of Ge. The disadvantage of this method was that the rapid d o n

between sodium tetrahyhborate and hydrochloric acid might generate a troublesome

foam, particularly when biological fluids were analyzed

(2) Derivatbation in the aqueoas phase

As world pollution increases, more and more concern is king given to toxic

metal-containing species, either inorganic or organic compounds. These materials are

generaily present in the water phase, so prior to the andysis by GC, which can do

speciation weii, it is necessary to perform an extraction of these metal-contahing species

from the aqueous matrices to the organic phase. The most popular uoy today is to use

sodium tetraethylborate to make an ethyl transfer to a metai center in aqueous solutions.

It has been used to determine Hg '"I, Sn IS2' and Pb IS3]. It is easily understood that this

method is more suitable for GC than the hydnde generation method, as the metai-

containhg ethyl derivatives are more stable than the corresponding hydrides.

(3) Derivatbation by Grignard reagent

A Grigaard reagent is very active, so it can react with some metal-containing

matenals, either inorganic or organic species. Good redts '541 were obtained using the

Grignard reaction for the determination of Hg. This rnethod had k e n practically used

in the detemination of methyl- and ethyl-mercury in naturai water where the detection

limit was 0.05 ng Hg/L. A Grignard reagent is more often used to detennine organotin

compounds and to do organotin speciation. For doing the speciation, different Grignard

(64-661 reagents were once used to do rnethylation 156591, ethylation IW3] , pmpylation ,

butylation 16'! pentylation [68-n1 and hexylation ['" of tin-containing species. By the

combination of complexation and aikylation with propyl magnesiun chlonde,

organolead could be detennined sensitively with a detection limit of

0.03-0.2 pg 1741. Many of these det enninafions were performed using the

microwave-induced plasma-atomic emission detector (M[P-AED).

1.4. Research objectives

First, we want to find more elements which can be detennined with higher

sensitivity using holophotal FPD with a s a stoichiometric flame. More spectra at

different conditions wiU be obtained for some hown "FPD sensitive" elements to

acquire more understanding of their cherniluminescent chanrcteristics, which c m be used

to enhance both sensitivity and selectivity for the d e t e e t i o n of these elements. In

order to widen the application of FPD in GC, we want to try to achieve multi-element

determination and speciation by using holophotal FPD with the smdl flame under

stoichiometric gas flow conditions.

Another area important in pmcticai Iife is the detennination of some toxic heavy

rnetals. As some present forms of these metais are not volatile enough to be detected by

GC directly, we want to obtain some simple denvatization methods for their

determination with our cheap, but sensitive and selective FPD.

CAAPTER 2

EXPERIMENTAL

A 1990 Shimadni GC-8APFp was used for all the foilowing experiments. The

chrornatographic column was 100 x 0.3 cm i.d Pyrex tubing packed with 5% OV-101 on

Chromosorb W (AW), 100-1 20 mesh (about 150-125 pm diameter) particles. Some dass

wool was placed on both the idet and exit of the column. The detector used was a FPD

modified by iastalling a parabolic mirror to enhance the iight through-put ( d e d the

holophotal chamel). A circular misror, machineci h m aliimin~m~'~, was placed behind

the modified flame jet. A 6 x 0.25 inch quartz rod, bent to nearly a right angle to fit the

position of the injection port, was used for measuring spectra. This system was

designated as the light guide channelP6! ûptical filters used were ali nom Oriel (250

Long Beach Blvd., P.O.BOX 872, Stratford, CT. USA 06497). Either an R-1104 or an

R-268 photomultiplier tube was used for the light detection. Both of these tubes were

fiom Hamamatsu (Hamamatsu Corporation, 250 Wood Avenue, Middlesex, NJ, 08846).

The signal was recorded with a Shimadzu millivolt recorder (mode1 R- 1 12) after passing

ùirough an analog filter (RC=l second except where specifically indicated). The carrier

gas was prepinified nitrogen tiom Linde ( Linde Union Carbide Canada Ltd., Toronto,

Ontario). The carrier gas passed through a hydmcarbon filter (HT 200-2,

Chromatograptiic Specialties Incorporated, Brockville, Ontario) and a g l a s moistue trap

14

(G BMT-100-2) fiom the same company . Hydrogen and air were also fimm Linde and

passed through similar devices for purification. Reagents used were aU standard analyte

samples (>95 % pure) fkom Aldrich Chernical Company, Milwaukee, W h Fluka

Chernical Corp., Ronkonkana, N.Y.; Ventmn Alfa Inorganics, Danvers, Ma; ALfred

Bader Library of Rare Chemicals, Division of Aldrich Chernical Company; or Strem

Chemicals Inc., Newbrnyport, Ma.

CHAPTER 3

THE BEHAVIOR OF LEAD IN THE SMALL STOICHIOMETRIC FLAME

3.1 Measurement of the lead spectrum.

3.1.1. Introduction

Prior to this study, the spectrum of lead had ken obtained using a variable

interference filter but there has been no attempt to search for the emission of lead in

the ultra-violet region using a small flame at stoichiometric conditions. In order to do

this, a monochromator whose wavelength can extend to 300 nm is suitable. A grating

monochromator with a focal length of 1/4 m was selected and a special fitting was

designed for the interface betweeo monochromator and detector. This fitting had

a two-way adjustable screws which was used to obtain a Iarger range for focus. The

simple schematic diagram is shown in Fig. 1.

3.12 Experimental

The lead spectrum was detected. The response was recorded as coulombs/moIe

(C/mole) The compound used was teûaethyllead ( TEL), the wavelength was changed

manually and the spectrum was collected by repeated injection. A 2 mm dit was

selected for both the entrance and exit of the monochromator which resulted in a

bandpass of about 6.7 nm. Flow rates were nitrogen 20, hydrogen 16 and air 40 d m i n ,

i.e., the srnail stoichiornetnc flame (same in al1 the following work except where

17

specificaily indicated). In the nrst charme1 (CHI), the PMT tube w d was a Hamamatsu

R-374 at -755 V, a 475 nm LP filter was used . The light-guide channel was the second

channel (CH2), the PMT tube used was a Hamamatsu R-268 at - 200 V and no opticai

filter was used in Cm. The injected amount of tetraethyl lead was 500 ng for each

wavelength and the column temperature was always set at 1 1 0 ' ~ during the whole

experiment.

3.13 Resalts and discussion

The cornpiete lead spectnim is shown in Fig. 2. There is, indeed, a feature in the

region between 300 nm and 360 MI, which is a band atnributed to "D systems" of PbO.

The other feanires measured using the quarfer-rneter are the same as those in other Iead

spectram , including the characteristic band between 420 m and 5 10 nm which

belongs to the "B systems". MeanwhiIe, there is another intense peak which had not been

determined before. It is located in the ültra-Violet region, where most elements have no

response in the FPD, and its central wavelength is about 330 nm, so there is some

distance fkom OH band (whose centrai wavelength is 306 nm). This is a good

characteristic which can be used for analyticai purpose. Theoreticaily, the determination

of lead in the Ultra-Violet region shouid give better selectivity than using a longpass

filter.

3.2 Analytical application of the Ultra-violet band of P b 0

3.2.1 Experimental

To investigate if the Pb0 peak at about 330 nrn can be used to

19

impmve the determination of lead, several diffarnt filters were selected to masure the

calibration curves of tetraethyl lead in cornparison to dodecane. First, a 385 m LP filter

was used It was then replaced by a 340 nrn interference filter. Whea using the latter,

strict optimization of the gas flow conditions was perfomed since this filter was not

usually used for the determination of organometailic compounds under stoichiometnc

conditions with a smaU flame. Then, under the optimum conditions, calibration curves of

temthyl lead and other compounds containhg elements which might interfere with lead

determination were made. These elements included: S, Mn, P, N, aromatic carbon and

aliphatic carbon. A practical application of the above technique using the 340 MI

interference fiiter was investigated using tetraethyllead and tetrabutyllead ( TBL). The

chromatogram of a mixhue containing 2.0 ng tetraethyllead and and 2.5 ng tetrabutyllead

was obtained using a temperature program. Al1 the above compounds were dissolved in

acetone to make stock solutions and diluted with the same solvent for working solutions.

3.2.2 Results and discussions

Fig. 3 shows a calibration cuve of tetraethyllead and a calibration curve of

dodecane obtained using the 385 nm LP filter. The selectivity, i.e., mole Pb/mole C, was

around 10 3. The detection limit for the element Pb (S I N , =2 ) was

1 0 -14 ( mole Pbhecond ).

Fig. 4 and Fig. 5 show the results of the optimization ( 340 nm interference filter)

of air and hydrogen respectively. The sensitivity for the detemination of Pb couid be

increased when the air fiow became higher until the air flow was so high that it

extinguished the d flame. Similarly, the signai over noise ratio increased if the

hydrogen flow was decmsed until the hydrogen fiow was so Iow that it coufdn't sustain

a stabIe flame. The optimum gas flow were: hydrogen: 16 U m i n , air: 40 &min,

which were M a r to previous parameters. The fl ow of nitrogen ( carrier gas) was not

altered . Slightly better seflsitivity wuid be achieved with higher fiow of nitmgen,

however, the flame was too unstable, thus, normdy, the nitmgen flow was kept at

20 mWmin,

Fig. 6 shows the wmplete caliiration cuves for Pb and S using the 340 nm

interference filter. The other cmes were paitiaiiy m d at the same conditions for

cornparison piirposes only. In Table 1, selectivity data were listed It can be seen that

the selectivity of the Pb determination against carbon, &g the 340 nm intefierence

filter, increased nearly four times relative to the method using the 385 n m LP filter. The

detection limit of the "340" is IO-'^.' ( mole PWsecond), which is siightiy higher than the

"385". So, for some high hydrocarbon-containing &ces, using the Pb emission in the

Ultra-violet region is better. The result of using the 340 nrn interference mter for the

separation of tetraethy1lea-d and tetrabutyfiead is shown in Fig. 7, cornplete separation for

the two organolead species at the set conditions was obtained.

Mechanisms of emissions of Pb and other FPD-responsitive elements

A paper on the discussion of the Pb emission Inl attributed the emission to a

kind of " slirfiice emission", which should have some special characteristics similar

=iog [mole element 1 second]

Table 1. Selectivity between lead and other

elements (mole Pblmole element)

- - - p .

Nitrogen

1 Aliphatic carbon 1

TEL

Fig 7. Chromatograms of 2.0 ng tetraethyllead + 2.5 ng tetrabutyllead. Temperature program, R268,750 V, RC=ls, 340 nm interference filter. Det: 250°c, chart speed: 2.5 d m i n , I and II represent different temperature increase speed 1 : 3Oc/min, II: 8'~/min. General conditions, hoIophotaI channel.

to Sn. The emiuion should depend on the chimney d a c e .

3.1 Experimentnl

Pb emission was checked visually nrst There was a " yeilowish b d " when the

compound came out of the colurnn, but no emission was observeci "amund the chimney"

as with Sn . Then measurements of the signal over noise ratio with and without a

chimney were made to observe ifthere was any difference relateci to the &âce of the

chimney. Os, Ru, Bi, P were also checked under the same conditions, both with and

without a chimney.

33.2 Resdts and discussions

Fig. 8 shows the chromatograms for identical amounts of tetraethyl lead both with

and without a chimney. It was observed that the signal over noise ratio was

approximately the same. Similar results, shown in Fig. 9, Fig. 10, Fig. 1 1, Fig. 12, were

observed for Os, Ru, Bi and P. This indicates, therefore, that "surface emission" is not a

factor.

3.4 Derivatization and determination of inorganic lead (II)

As organolead species can be sensitively detected by the FPD with a small

near-stoichiometric fiame, and as the detector is cheap and easy to handle, attempts are

worthwhile to widen its application to the more common aqueous systems.

3.4.1 Erperimental

A water solution of Iead (II) nitrate was denvatized and determined by the

Fig 8. Chromatogmms of 5.0 ng tetraethyflead hydrogen: 15 rnL/mk, a i r 40 mWmin, R.268, EN, 340 nm interference nIter, circular mirror. Col: 1 1 O'C, Det: 1 8o0c, RC=l S. A: without chimney B: with quartz chimney

Fig 9. Chromatograrn of 5 ng osmocene, nitrogen: 12 mL/min, hydrogen: 15 mUmin, air: 40 xnL,/min. R268,540V, 473 nm LP filter, circuiar rnirror. Col: 1 7 0 ~ ~ ~ Det: 2 3 0 ' ~ ~ RC=ls. A: without chimney B : with qua.& chimney

Fig 10. Chromatogram of 0.5 ng nithenocene, nitrogen: 12 mL/mh, hydrogen: 15 mL/min, air: 40 ml/min. R268,540V, 475 nm LP filter, circular mirror. Col: 1 7o0c, Det: 230°c, RC=l S. A: without chimney B: with quartz chimney

Fig 11. Chromatogram of 1 .O pg triphenyi bismuth, nitrogen: 12 mE,/min, hydrogen: 15 ml/min, air: 40 aL/min. R268,540Vy 473 nm LP filter, circular rnirmr. Col: 170°c, Det: 2 3 0 ~ ~ ~ RC=ls. A: without chimney B: with quartz chimney

Fig 12. Chromatogram of 10 ng ûis @entafIuorophenyl) phosphine, nitrogen: 12 mllmin, hydrogen: 15 d / m i n , air: 40 mWmh R268, 540V, 475 nm LP filter, circular mirror. Col: 170°c, Det: 230°c, RC=ls. A: without chimney B: with quartz chimney

33

following methoci. First, lead (II') nitrate was transferred to a f o m which could dissolve

in an organic phase. Then, part of the organic p k was injected into GC. The

derivative reagent used was sodium tetraethyiborate ( NaBmt),). The pmduct was

extracteci with benzene dirting derivatization. For the determination of high arnounts of

Iead (II) (concentration of element lead (II) >50 ppb), part of the organic phase was taken

out by a micro-syringe and injecteci directiy into the GC colum.. When the concentration

of lead ( II ) was beiow 50 ppb, preconcentration was performed before injection.

Typical volumes of the organic phase used were ImL. The preconcentration was carried

out by the foiiowing procedure. AAer derivatization, the reaction vessel was filled with

water to make the organic phase reach the neck of the vessel. With a Pasteur pipette put

just above the surface, the orgsnic phase was flushed with nitrogen at slow flow to less

than half of the initial volume. Then the organic phase was carefbiiy taken out with the

same pipette and evaporated to 20 pl with nitrogen at slow flow in a precalibrated "reacti

vial"(typica1 volume ImL, PIERCE), 1 PL out of 20 pL organic phase was introduced

into the GC-FPD system running with a small flame under stoichiomehic conditions.

Next, it was necessary to confirm the identity of the derivative product In order

to do this, retention times of the derivative product and pure tetraethyl lead were

compared. in this experllnent, usually, 2 mL 0.175M sodium hydroxide was added to 20

mL of the lead (II) solution. The weight ratio of sodium tetraethyiborate to Iead (II) was

around 20.

The derivatization procedure was then optimized by varyuig the pH-value and the

weight ratio of sodium tetraethylborate to lead (II). Solutions with pH-values between 4

34

and 10 were obtained by adding 2 mL mixture of ammonia(2S%(m/v) and cieic acid

(2.0 g monohydrate/MO mL water) with the corresponding pH. However, solutions with

pH=2 and pHX0 were obtained by using nitric acid (1 molek) and sodium hybxide

(1 mol&). Finally, calibration c w e s were obtained under optimum conditions using

5 mL beazene for extraction. Then 1 rnL benzene was useci, both with and without

evaporation.

3.4.2 Results and discussions

Fig. 13 shows several chromatograms demibing the derivatization of inorganic

Iead (II). Retention times of a blank and pure tetraethyllead were compartd to that of the

derivative. The retention time of the pure tetraethyllead and that of the derivative agree

wei1. Meanwhile, coinjection of the derivative and pure tetraethyllead with a comparable

peak height was performed. A single peak was observed.

Optirnization results for the procedure of derivatization were plotted in Fig. 14

and Fig. 1 5. The optimum pH-value was around 10- 12. The optimum weight ratio of

sodium tetraethylborate to lead (II) was found to be above 20.

Fig. 16 and Fig. 17 show the calibration curves obtained using 5 rnL benzene and

1 mL, benzene. It can be seen that the absolute deteetion limit of this method is

1 ppb. During the above determinations, a 475 nrn LP fiIter rather than the 340 rn

interference filter was used. The reason is that the 475 nrn LP filter seemed better suited

to fiiture multi-element detections.

Fig 13. Chromatngmns conceming the deriVElfiZafion of hiorganic lead 0. (A). reagmt blank before derivatkation. (B). 5 ng pure tetrazthyiiead in benzene. (C). 0. 1 pL sample (quivalent to 10 ng tetraethyIIed)

after derivatking with 20 WIW sodium tetraethylborate. 0). CO-injection of (B) and (C).

547V. R268,475 nm LP, RC=l s, col: 1 1 OOC, det: 1 gooc, stoichiorn&c .

Fig 14. Effect of the pH-value on the denvatintion yield of &xganiic lead 0.

w (sodium tetraeth ylborate)Ew(lead(l 1))

Fig 15. Effect of the weight ratio (w/w) of sodium tctmethylborate to Iead on the derivatkation yield of inorganic lead 0.

log( concentration (ppb) )

Fig 16. Calibration c iwe of the inorganic lead (II) d e r i v M by sodium tetraethylbonite. Derivatkition procedure: lead ions @) +20 mL H20 + 2.0 mL O. 175 moVL NaOH +5 mL beiuene, stir 40 minutes, inject luL benzene phase.

GC conditions: R268,550V, 475 nm LP, Col: 1 1 O'C, et: 1 gooc. RC=l s, stoichiometric conditions, hoiophotai channel.

SIMULTANEOUS DERIVATIZATION AND DETECTION OF SOME TRANSITION ELEMENTS

1.1. Introduction

As applications of noble metals in many fields such as chernid engineering,

microelectronics and medicine grow rapidly, it is important to develop the rnethods to

detect them both individually and simultaneously. Usuaiiy, the close chernical similarity

of ruthenium and osmium causes many interference problems in the simultaneous

detection of these two elements, which makes pre-separation of nrthenium and osmium

necessary 17'* ''). Recently, Blacerzak and Swiecicka used direct and third-order

denvative spectrophotometry to determine ruthenium and osmium simuitaneously

without pre separation [''I. However, the linear concentration range for rutheniun

detennination was 0.07-20 pg Ru/mL, and the linear range for osmium was

0.02-20 pg Os/mL . It is meaningfid to M e r improve these ranges.

Iron is a common element which cm be determined by many methods,

e.g., MTP-AED 1801, electrochemistry [*", etc. Simuftaneous detennination of antimony ,

germanium and tin was once studied in high purity iron metais using AAS even

though the procedure was quite tirne consuming (4-5 hours). A literature s w e y provided

no reference of simultaneous detection of the inorganic species of the iron group by GC.

41

It is weli known that the FPD can be used to detect transition elements with high

sensitivity '? Under the condition of a small stoichiometric flame, metallocene

compounds usually have optimal responses which make it possible to detect

mdti-transition elememts by converting inorganic transition elements to their

corresponding metailocenes.

4.2 Derivatkation of transition elements with lithium cyclopentadienylide

The dexivaikation of inorganic species of the iron gmup and of nickel were

studied individdy using lithium cyclopentadienylide. The major factors that might

influence the yield of the derivatization process for iron and rutheniun were checked .

Finally, the iron group elements were shultaneously denvatized and detected with FPD

at the condition of a small flame under stoichiometric conditions. Similarly, Von and

nickel were simultaneously derivatized and detected.

The stock solution of 700 p g / d iron (II) chloride tetrahydrate was made in

anhydrous tetrahydrofuran (T'Hl?). 125 mg/mL mthenium 0 chloride hydrate and

250 mg/mL nickel (II) chloride hexahydrate were used in aahydrous ethanol as stock

solutions. Working solutions of the above compounds were made by diluting the

respective stock solution with anhydrous THF. The concentration of working solutions

were: 70 pg/mL iron (II) chloride tetrahydrate, 125 pg/mL rutheniun (III) chioride

hydrate and 400 pg/mL nickel (II) chioride hexahydrate . 0.180 g commercial EM

osmium 0 tetroxide was weighed in a s d capped vid and 0.8 mL concentrated

hydrochlonc acid was added to dissolve the solid, the solution was then evaporated by

inserting the via1 in a heating block. A small flow of nitrogen was used to aid the

evaporation. When the vid was almost dry (about O. 1 mL), the evaporation process was

stopped and anhydrous THF was added to make the total volume of 0.6 mL, this was the

stock solution of osmium containing compomd. Mer a 1 O00 fold dilution of the stock

solution with éinhydrous THF, the working solution was equivalent to 300 pg/mL

osmium 0 temxide. In a glove bag under nitrogen, part of the working solution of

iron (II) cbloride t d y d r a t e or rutheniun 0 chloride hydrate or osmium containing

compound was put into a s m d via1 which contaiaed a minimum amount of 400 mol/mol

lithium cyclopentadienylide dissolved in suitable amount of anhydrous THF. The

mixture was heated in the hating block at 5 0 ' ~ (the temperature was monitored by a

thennocouple) to react. Then the via1 was taken out of the bag and a suitable volume of

the derïvatized product was chromatographed. As nickelocene easily decomposed at high

temperature, the procedure for the derivatization of nickel (II) chloride hydrate was

similar to the that for hou group compounds except that it was performed at room

temperature.

The major factors that might influence the derivathtion process were checked by

taking iron (II) chloride tetrahydrate and ruthenium (III) chloride hydrate as examples. A

17.5 pg iron (II) chloride tetrahydrate working solution was mixed with 10 mg lithium

cyclopentadienylide in a vial, and the volume was made to 2 mL with anhydrous THE

For cornparison, two vials each containing the same amount of iron (II) chloride

43

tewydrate and lithium cyclopentadienylide were preparcd. Then one of the vials was

shaken 30 minutes at room temperature to form mixture 1, the other via1 was heated at

around 5o0c for 30 minutes to fom mixture 2. Same volumes of mixture 1 and mixture

2 were injected into the GC separately. Then, to mixaire 1,2 mL 1.0 moVL hydrochlonc

acid and I d hexane were added, the via1 was shaken 10 minutes, and the organic layer

was removed. Then another 1mL hexaae was added and the extraction repeated. The

nrSt exlractant (mixhne3), the second extnictant (mixture 4), and the residue in THF

(mixture 5) were collecteci in different sample vials. Mixture 3, mixture 4 and mixture 5

were chromatographed separately to compare the d t s . The effect of the reagent

amount on the yield of the derivatization of iron (II) chloride tetrahydrate was checked

with 35 pg iron (II) chlonde tetrahydrate and different amout of lithium

cyclopentadienylide solution (about 62.5 mg/mL) in anhydrous THF with the total

volume of 4 mL. Similady, the effect of the reagent amount was checked with 10 ng

mthenium 0 chloride hydrate and different amounts of lithium cyclopentadienylide

(about 50 pg/mL) in anhydrous THF, with the total volume of 2 rnL adjusted with THF.

To decrease the cost of the derivatization process, a more economical

methodology was proposeci which involved preparation of fiesh sodium

cyclopentadienylide from sodium metal and freshly prepared cyclopentadiene. Typically,

20 rnL bis(cyc1opentadiene) was placed into a round bottom flask comected to a

hctionating column and the product was collected with a dry flask immersed in a

mixture of ice and sodium chioride. Imrnediately after the cracking process, 2 rnL

cyclopentadiene was allowed to react with about 0.2g sodium metai distributed in

44

auhydrous THF in a three neck round bottom flask. The reaction was perfonned under a

small nitrogen flow and kept below - 5 ' ~ by immersing the flask Uito a bucket of ice and

sodium chloride. When the colour of the solution didn't change and it stopped bubbling ,

2 mL sodium cyclopentadienylide was taken out with a syringe and placed in a capped

vial which contained the rnetal compounds. Just before using, the syringe was flushed

with nitrogen, then the tip of the needle was sealed with a septum and the assembly of the

syringe was wrapped with paranlm. Other steps of the derivatization procedure were the

same as those using Lithium cyclopentadienylide as the denvatizing ragent.

4.3 ResuIts and discussion

The resuit of the derivatization of iron (II) chlonde tetrahydrate by lithium

cyclopentadienylide is shown in Fig 1 8, Fig 19, Fig 20 and Fig 2 1. No injection and

pure tetrahydrofiiran were first checked in order to ensure the cleanliness of the system.

The denvatized product and pure ferrocene were compared according to retention tirne. It

cm be concluded that the fist peak which eluted at 5.5 minutes was ferrocene.

Similarly, the resuits for the derivatization of ruthenium(III) chloride hydrate,

osmium containing chloride and nickel (II) chloride hexahydrate by lithium

cyclopentadienylide are shown in Fig 22, Fig 23, Fig 24, Fig 25, Fig 26, Fig 27, Fig 28,

Fig 29, Fig 3 0, Fig 3 1, Fig 32 and Fig 3 3, respectively . Al1 the derivatized products were

confirmed by comparing their retention times with respective pure compounds, and by

CO-injection.

O 5 10 15 time (minutes)

Fig 18. Chromatognuns concerning the derivatizatim of iron (II) chlonde tetrahydrate by lithium cyclopentadienylide. (A): no injection. (B): 0.8 pL pure tetrahydrofiuan (anhydrous).

GC conditions: temperature program: 130'~- 1 5ooc, 2Oc/min, Det: 190°c, R268,540V, 475 nrn LP, RC=ls, Att: 1x16. chart speed: 2.5 d m i n , holophotai channel, stoichiometric flows.

O 5 10 15 time (minutes)

Fig 19. Chromatograms conceming the derivatkition of Kon @) chlonde tetrahydrate by lithium cyclopentadienylide. (C): 0.4 pL pure THF (anhydrous) + 0.4 pL blank.

GC conditions are the same as in Fig 18.

time (minutes)

O 5 10 15

time (minutes)

Fig 20. Chromatograms concaning the derivatization of iron (Ii) chionde tetrahydrate by lithium cydopentadienylide. 0): 0.4 pL pure THF (anhydrous)+ 0.4 pL, derivatized product. (E) : 0.8 pi, derivatized product.

GC conditions are t h same as in Fig 18.

O 5 10 15 time (minutes)

O 5 10 15 tirne (minutes)

Fig 2 1. Chromatograms concerning the denvatidon of iron (II) chloride tetrahydrate by lithium cyclopentadienylide. (F): 0.4 pL pure TEP (anhydrous) + 0.4 pL pure ferrocene

in THF( 1 ng/&). (G): coinjection of 0.4 pL derivatized product with 0.4 pi,

pure ferrocene in THF (1 @a). GC conditions are the same as in Fig 18.

O 5 10 tinte (minutes)

O 5 10 fime (minutes)

Fig 23. Chrornatograms conceming the derivatkation of rutheniun 0 chloride hydrate by lithium cyclopentadienyiide. (C): 0.2 pL pure THF (anhydrous) + 0.4 pL bblank @): 0.4 fi pure THF (anhydrous) + 0.2 pL denvatized product.

GC conditions are the same as in Fig 22.

time (minutes) O 5 10

time (minutes)

Fig 24. Chrornatograms concefning the derivatization of rutheniun (m) chloride hydrate by lithium cyclopentadienylide. (E): 0.2 pL pure THF (anhydrous)+ 0.4 pL derivatized product. (F): 0.4 jL pure THF (anhydrous) + 0.2 pL pure ruthenocene

in THF (2 nu@). GC conditions are the same as in Fig 22.

time (minutes)

Fig 25. Chromatograms concerning the derivatkation of ruthenium (III) chionde hydrate by lithium cyclopentadienylide. (G): coinjection of 0.4 pL derivatized product with 0.2pL

pure ruthenocene in THF (2 ng/pL).

GC conditions are the same as in Fig 22.

0 2 4 6 8 t h e (minutes)

Fig 26. Chromatograms concerning the derivatkation of osmium (Vm) tetroxide by lithium cyclopentadienyiide. (A): no injection. (B): 0.8 pL pure THF (aahydrous).

GC conditions: Col: 175'~, Det: ~IO'C, R268,540V, 455 nm LP, RC=ls, Att: 1x16, chart speed: 2.5 d r n i n , holophotal channel, stoichiometric flows.

0 2 4 6 8 time (minutes)

Fig 27. Chromatograrns conceming the derivatkition of osmium 0 tetroxide by lithium cyclopentadienylide. (C): 0.7 pL blank. (D) : 0.4 pL pure THF (anhydrous) + 0.2 pL denvatized product.

GC conditions are the same as in Fig 26.

0 2 4 6 8 0 2 4 6 8 the (minutes) time (minutes)

Fig 28. Chrornatograms conceming the derivatization of osmium 0 tetroxide by lithium cyclopentadienyiide. (E): 0.2 PL pure THF (anhydrous) + 0.4 pL derivatized product 0: 0.4 pL pure THF (anhydrous) + 0.2 pL pure osmocene

in THF (5 ng/jL).

GC conditions are the same as in Fig 26.

Fig 29. Chromatograms conceming the derivatization of osmium (VIII) tetroxide by lithium cyclopentadienylide. (G): coinjection of 0.4 pL derivatized product with 0.2 PL

pure osmocene in THF ( 5 ng/pL).

GC conditions are the same as in Fig 26.

O 4 8 1 2 time (minutes)

Fig 30. Chromatograms conceming the derivathtion of nickel (II) chloride hexahydrate by lithium cyclopentadienylide. (A): no injection. (B): 0.8 p L pure THF (anhydrous).

GC conditions: Col: 135*~, Det: 200°c, R268,540V, 475 nm LP, RC=ls, Att: 1x32, chart speed: 2.5 d r n i n , holophotal channel, stoichiometric fiows.

-

O 4 8 1 2 üme (minutes)

O 4 8 1 2 tirne (minutes)

Fig 3 1. Chromatograms conceming the derivatization of nickel (II) chloride hexahydrate by lithium cyclopentadienyiide. (C): 0.6 pL bblank. (D): 0.4 pL pure THF (anhydrous)+ 0.2 pL derivatized product.

GC conditions are the same as in Fig 30.

O 4 8 1 2 üme (minutes)

O 4 8 1 2 time (minutes)

Fig 32. Chromatograrns conceming the derivatkation of nickel (II) chloride hexahydrate by Lithium cyclopentadienylide. ) : 0.2 pL pure THF (anhydrous)+ 0.4 pL derivatited product. (F): 0.4 pL pure THF (anhydrous) + 0.2 pL pure nickelocene

in THF (1 0 nglpL).

GC conditions are the same as in Fig 30.

O 4 8 1 2 time (minutes)

Fig 33. Chromatograms concerning the derivatization of nickel (II) chloride hexahydrate by lithium cyclopentadienylide. (G): coinjection of 0.4 pL derivaîized product with 0.2 pL

pure nickelocene in THF (1 O ng/pL).

GC conditions are the same as in Fig 30.

For the derivatization of iron (II) chloride tetrahydrate, the results for the

optimization of the reaction tirne and temperature, the cornparison of non-extraction and

extraction process are show in Fig 34. The effect of the reagent amount is shown in

Fig 35. In Fig 34, 1,2,3,4, 5 represent mixture 1, mixture 2, mixture 3, mixture 4 and

mixture 5 as explained in the experimental part. The solid line was not drawn in

Fig 34 because there was no direct comection between Merent mixtures. The best

condition was non-extraction, room temperature or 5 0 ' ~ for 30 minutes. From Fig 35,

400 moVmo1 reagent was enough for the completeness of the derivatization.

The similar optimization resuits for the derivatkation of rutheniun (III) chionde

hydrate are shown in Fig 36, about 1000 times excess ragent was needed for the

denvatization . The results for optimizing the reaction time and temperature are not

show as they were similar to those obtained fhm iron (II) chloride tetrahydrate.

The mixture of iron (II) chloride tetrahydrate and nickel (II) chloride hexahydrate

were derivatized with sodium cyclopentadienylide. The results are shown in Fig 37,

Fig 38 and Fig 39. Based on the same reason as mentioned before, the derivatintion

proceeded at room temperature. From the cornparison of the retention tirne and the

and the CO-injection results of derivatized products with pure ferrocene and nickelocene,

inorganic species of iron (II) and nickel (II) could be denvatized'by sodium

cyclopentadienylide just as by lithium cyclopentadienylide. The problem was that the

fernocene peak and the nickelocene peak didn't resolve completely at the experimental

conditions, however, that was amibuted to the short length (1 meter) of the column used.

The resuits from the derivatization of the mixture of iron (II) chioride

Fig 34. Effect of d i f f m t proce~s on tht &vatLation yield of iron (II) chloride tetrahydrate with lithium c yclopentadien ylide.

mole ratio

(iron (1 1) chloride tetrahydrate / lithum cyciopentadienylide)

Fig 35. Effect of ragent amount on the derivatkation yield of iron (II) chioride tetrahydrate with lithium cyciopentadienylide.

mole ratio

(ruthenium (III) chlonde hydrate I lithum cyciopentadienylide)

Fig 36. Effect of reagent amount on the derivatization yield ofhthenium 0 chioride hydrate with lithium cyclopentadienylide.

time (minutes) time (minutes)

Fig 37. Chromatograms concerning the denvatization of the mixture of iron (II) chloride tetrahydrate and nickel (II) chloride hexahydrate by sodium cyclopentadienylide.

(A): 0.6 p.L pure THF (aahydrous). ) : 0.6 pL reagent bl&

GC conditions: Col: 130°c, Det: 200°c, R268,530V, 455 nm LP, RC=l s, Att: 1x32, chart speed: 2.5 ~ILIIirnin, holophotai channel, stoichiometric flows.

O 5 I O time (minutes)

O 5 10 time (minutes)

Fig 38. Chromatograms conceming the derivatkation of the mixture of iron (II) chioride tetrahydrate, and nickel (II) chloride hexahydrate by sodium cyclopentadienylide.

(C): 0.6 p.L derivatized product. 0): mixture of 0.5 pi, pure ferrocene (1 ng/pL) + 0.1 pL

pure nickelocene (20 @a). GC conditions are the same as in Fig 37.

O 5 10 time (minutes)

O 5 10 time (minutes)

Fig 39. Chromatograms concemhg the derivatkation of the mixtlne of iron (II) chloride tetrahydrate, and nickel (II) cbioride hexahydrate by sodium cyclopentadienylide.

(E): 0.6 PL derivatized product + 0.1 PL nîckelocene( 20 ng/pL). (F): 0.1 pL pure ferrocene( Sn@&) + 0.6 pL derivatized product.

GC conditions are the same as in Fig 37. -

68

tetrahydrate, ruthenium chloride hydrate and osmium containing compound are

shown in Fig 40, Fig 41, Fig 42 and Fig 43. Even though it seemed more reasomble to

use a temperatrire prognim to do the simuitaneous detection, isothemd operation was

s td i adopted since the baseline drifted when a temperature program was wd

A method to différentiate commercial THF and anhydrous THF (obtained by

distüiing the commercial THF with sodium metal) was accidentally found during the

studies of derivaiizations. Using GC-FPD, a peak of dcnown identity appeared when

0.7 pL commercial THF was injecteci, however, the same amount of anhydrous THF

didn't show anything at the same condition iïsted in Fig 44.

time (minutes) Fig 40. Chromatograms concerning the derivatization of the m i x h

of iron (II) chloride tetrahydrate, rutheniun chloride hydrate and osmium containing compound by sodium cyclopentadienylide. (A): 0.8 pL pine THF (anhydrous). (B): 0.7 pL reagent blank

GC conditions: Col: 135'~, Det: 200°c, R268,530V, 455 nm LP, RC=1 s, Att: 1x32, chart speed: 2.5 d r n i n , holophotal channel, stoichiometrk flows.

O 6 12 18 time (minutes)

O 6 12 18 time (minutes)

Fig 41. Chromatograrns conceming the derivatkation of the mixture of iron 0 chloride tetrahydrate, naîhenium (III) chlonde hydrate and osmium containing compound by sodium cyclopentadienylide. (C): 0.7 pL derivatization product 0): pure fernocene (500 pg) + pure ndhenocene (1.5 ng) + pure

osmocene (2.5 ng). GC conditions are the same as in Fig 40.

. time (minutes) tirne (minutes) Fig 42. Chromatograms conceming the derivatintion of the mixture

of iron @) chioride tebrahydrate, ruthenitun (III) chloride hydrate and osmium containing compound by sodium cyclopentadieny lide. (E): CO-injection of 0.7 pL denvatization product with

500 pg fmcene. 0: CO-injection of 0.7 pL denvatization product with -

0.8 ng nithenocene. GC conditions are the same as in Fig 40.

O 6 12 18 time (minutes)

Fig 43. Chromatograms conceming the denvatization of the mixtlne of iron (ll) chloride tetrahydrate, rutheniun (III) chloride hydrate and osmium containhg compound by sodium cyclopentadïenylide. (G): CO-injection of 0.7 pL denvatized product with

5 ng osmocene GC conditions are the same as in Fig 40.

Fig 44. Cornparison of the chromatogtams of dried THF ( distiUed through sodium) and untreated commercial THF. (A). 0.7 pL dried THF. (B). 0.7 pL untreated THF.

GC conditions: Col: 175 OC, Det: 210 OC, R268, Att: 1x1 6,54OV, 455 nm LP, RC=I s, holophotal channel, stoichiometric flows.

SIMULTANEOUS DERIVATATION AND DETECTION OF INORGANIC GERMANIUM, TIN AND LEAD SPECIES WITH AND WITHOUT INORGANIC IRON GROUP SPECIES

5.1 Introduction.

There are many reports on the determination of th and lead because of

environmental concerns, especialiy regarding the organic species of these elements.

Speciation of organotin compomds in fish was sucessfully performed by Shawicy using

GC-AAS following rnicrowave-assisteci digestion, extraction and derivatization with .

sodium tetraethyl borate The detection limits for Sn as dimethyl t h was 1.5 ng/g fish

(fresh mas). Speciation of organolead is always of interest for analysts. The lowest

detection limit for the detection of Pb was at the fdg level according to a report by

Lobinski and CO-workers Germanium was not studied as much as th and lead, even

though some germanium containhg compounds, e.g., germanium tetrachloride, are toxic.

The most recent report on the speciation of organoge~nanium compounds were made by

Jiang and his colleagues

Although the derivatization method based on sodium tetraethylborate can be used

in aqueous matrices, the number of elements which can be derivatucd is limited h

order to reaiize simuitaneous determination of the inorganic species of Group 14

elements, diEerent kinds of Grignard reagent were evaiuated as denvatization reagents.

5 3 Experimental

5.2.1 Derivatization of organotin compounch with triphenylmagnesium bromide

Grignard reagent derïvaîhtion was first used to derivatize pure organotin

compounds: triethyltin chloride and tripropyltin chloride.

(a). Reagents

Triethyltin chlonde and tnpropyltin chloride were each dissolved in acetone to

make 1 pg SdpL stock solutions. 10 ng/pL working solutions were each made by

diluting with acetone. 100 pL phenyixnagnesium bromide (2.0 M in diethylether) was

mixed with 8 mL benzene and sealed to provide a ready solution for each individual

experiment .

(b). Procedures:

First, about 6 pL of each working solution of triethyltin chloride and tripropyltin

chloride was combined with 1 mL benzene to form hornogeneous mixtures, 1 pL out of

which was each injected into the GC running under the conditions in Fig. 45. Also

injected was 1 pL fksh phenylmagnesium bromide solution to ensure that there is no

effect from the Grignard reagent itself. Next, about 6 pL each working solution of

triethyltin chloride and tripropyltin chionde was mixed with 1 mL benzene and about

76

1 pL i L h phenyhagnesium bromide working solution. After shaking, 1 pL out of each

mi- was andyzed under the same conditions as ''the blank samples".

5 2 3 Simaltnneous derivatization and d e t d o n of iuorganic germaninmo,

inorganic th (IV) and inorganic lead (II) species

FoUowing the derivatization ofthe organic species, germanium (IV) chloride and

t i n o chioride working solutions were made directly h m the dilution of commercial

germanium 0 chloride and 1.0 M tin (IV) chloride solution in heptane with anhydrous

THF. The concentration of germanium (IV) chloride and tin (IV) chloride was: 2 pg/pL

and 1 pg/pL respectively. The lead nitrate stock solution was made by dissolwlg 0.250 g

solid in 0.5 mL water, the working solution was made by diluting the stock solution 1000

times with anhdrous THF.

The denvatization of inorganic germanium (IV), tin (IV) and lead (II) were

performed by &g a suitable amount of each working solution with butyimagnesium

chloride solution in diethylether to make a total volume of 4 mL, then the mixture was

heated at about 35'~ for 30 minutes with occasional shaking. Part of the mixture was

injecteci into the GC.

5.2.3 Simultaneous derivatization and detection of inorganic species containing

germanium 0, th (IV), lead 0, iron (II), mtheniurn (ITI) and osmium.

In order to do simuitaneous detection of germanium (IV) chloride, tin (IV)

chioride, iron (II) chloride tetrahydrate, rutheniun (III) chioride hydrate and osmium

containing compound, the stock solution of 200 mg/rnL iron (II) chloride tetrahydrate

77 was made in anhydrous THF. 125 mg/mL ruthenium (III) chloride hydrate was made in

anhydrous ethanol as stock solution. With the same procedure as used in Chapter 4, the

stock solution of osmium containing compound, which was equivalent to 300 rng/mL

osmium 0 tetroxide, was made in m. The working solution used was 5 m g M

of lead (II) nitrate, 20 pg/pL iron (II) chloride tetrahydrate, 1.25 pg/pL, rutheniun (III)

chloride hydrate and the osmium containing chloride which was equivalent to 30 mg/mL

osmium 0 tetroxide.

In the derivatkation of the six elements, about 150 mg lithium

cyclopentadienylide was placed in a via1 which stayed in a glove bag for 30 minutes, then

a cap with septum was inserted on the viai, each working solution and about 3.4 mL

butylmagnesium chloride were placed in the via1 to make the total volume of the mixture .

3.5 d.

A quartz chimney and a glass chimney was separatdy tried to compare the results

for the detection of pure ferrocene, ruthenocene, osmocene, tetrabutylgermanium,

tetrabutyltin and tetrabutyl lead. F W y , with a glas chimney and a "big" flame

(hydrogen : 190 mL/mia, nitrogen: 30 rnLhin, air: 50 d m i n ) , the above six pure

compounds were simultaneously detected using a temperature program.

5.3 Results and discussion

Chromatograrns of the derivatized products fiom pure triethyltin chloride and

tripropyltin chloride by lithium cyclopentadienylide are shown in Fig 45 and Fig 46.

1 O'C / min I

80'~ 2 0 0 ~ ~

IO'C I min b i O'C / min

Fig 45. Chromatograms of (A): phenylrnagnesium bromide; (B) triethyitin chloride; (C): tripropyltin chioride under the same conditions. temperature program, 8 0 ' ~ - 200°c, 10'~/m.h, Det: 2 5 0 ' ~ ~ Att: 1x32, amount: 60 pg tin in (B) and (C), 394 nm interference Nter, 610V, R268, RC= 1 s, holophotal channel.

10% / min

Fig 46. Chromatograms of the derivatized products of @): triethyItin chloride; (E): tripropyltin chloride with phenyimagnesium bromide. temperature program, 8 0 ' ~ - 200°c, 10'~/rnin, Det: 250°c, Art: 1 x32, amount: 60 pg tin in (B) and (C), 394 nm interference filter, 6lOV, R268, RC=l s, holophotal channei.

80

Solutions of pure triethyltin chioride and tripropyltin chloride in bentene produced no

peaks, nor did the phenylmagnesium b r o d e in benzne. However, the derivatized

products each produced a significant peak.

The success of these derivatkations suggested that the Grignard ragent could

derivatize some organotin species directiy and this method might be applied to the

simultaneous detection of group 14 elements.

In order to investigate this possibility, the derivatization resuits for the mixture of

germanium (IV) chloride, tin (IV) chloride and lead (II) nitrate by lithium

cyclopentadienylide are shown in Fig 47, Fig 48, Fig 49, Fig 50, Fig 5 1 and Fig 52. The

flame used was a "big" flame, since with the smaii stoichiometric flame, it was found that

the noise level wodd increase too much after several injections of tin or germanium

containing compounds. The cornparison of the retention times of the pure compounds

and those of the derivatized products showed that the simdta~eous derivatization was

realized by using butylmagnesium chloride as the derivatization reagent. The

CO-injection resuk in Fig 52 confirmed this conclusion.

The comparative result fiom using a glas chimney and a quartz chimney for the

detection of tetrabutylgermanium, tetrabutyltin and tetrabutyl lead is shown in Fig 53. It

is clear that an about 3 orders of magnitude higher sensitivity codd be obtained for the

detection of tin with a quartz chimney compared to a glass chimney. This result is

consistent with the earliw observed surface enhancernent of t h ernis~ion '~~~.

The behavior of the pure compounds: ferrocene, ruthenocene and osmocene were

investigated with a glass chimney and a quartz chimney. In Fig 54, the comparative

Fig 47. Chromatograms concerning the derivathion of the mixture of lead (II) nitrate, tin (IV) chloride and germanium (IV) chioride by butyimagnesium chloride. (A): no injection; (B): 0.9 pL acetone.

GC conditions: Col: 120' C- 190' C , 10' C/min, Det: 240°c, R268, 540V, 455 nm LP, RC=l s, Ati: 10x4, chart speed: 2.5 d m i n , holophotd channel, glass chimney, hydrogen: 190 mWmin, nitrogen: 30 Wmin, air: 5 6 m ~ m i n .

O 5 10 time (minutes)

time (minutes)

Fig 48. Chrornatograms concerning the derivatization of the mumire of lead (II) nitrate, tin 0 chloride and germanium 0 chloride by butyimagnesium chlonde.

(C): 0.2 pL (20ng) pure TBL + 0.6 pL acetone.

(D): 0.2 pL (2 ng) pure TBGe + 0.6 pL, acetone.

GC conditions are the same as in Fig 47.

tirne (minutes) tirne (minutes) Fig 49. Chromatograms conceming the derivatkation o f the mixture

of lead (II) nitrate, tin (IV) chioride and germanium (IV) chionde by butylmagnesium chloride. (E): 0.2 pL (1 ng) pure tetrabutyl tin (TBSn) + 0.6 pL acetone. 0: 0.2 pL, (20 ng) pure TBL+ 0.2 pL pure TBSn (hg) + 0.4 PL

acetone. GC conditions are the same as in Fig 47.

Fig 50. Chromgrams concenllng the derivatkition of the mixture of iead (II) nitrate, t h (IV) chloride and germanium (IV) chloride by butyimagnesium chloride.

(G): 0.3 pL (30 ng) pure TBL + 0.3 p.L (1.5 ng) pure TBSn + 0.3 pL (3ng) pure teeabutyigermanium.

GC conditiom are the same as in Fig 47.

' T h e peaks are attributed to:

1- TBGe 2- TBSn 3. TBL

O 5 10 time (minutes)

time (minutes) O 5 10

time (minutes)

*The peaks are attribated to:

Fig 51. Chromatograms conceming the denvatization of the mixture of lead (II) nitrate, tin (IV) chloride and germanium (IV) chloride by butyimagnesium chioride.

(H): 0.8 pL pure butylmagnesium chloride. 0: 0.2 pl, sample + 0.6 pL acetone.

GC conditions are the same as in Fig 47.

Fig 52. Chromatograms conceniing the derivatization of the mixture of Iead (II) nitrate, tin (IV) chloride and germanium (IV) chloride by butylmagnesiurn chloride.

(1): 0.2 pL simple + 0.2 pL (20 ng) pure TBL + 0.2 pL (1 .Ong) pure TBSn + 0.2 pL (2ng) pure TBGe.

GC conditions are the same as in Fig 47.

*The peaks are attribnted to:

1. TBGe 2. TBSn 3. TBL

O 5 10 time (minutes)

Fig 53. Chromatograms of the mixtlire of 2 ng tetmbutyIgermaniurll, tetrabuty1tin and 20 ng tetrabutyilead.

(A): with quartz chimney, 1.5 pg TBSn. (B): with glass chîmney, 1 ng TBSn.

GC conditions: Col: 120' C- 190' C , 10' Chin , then isothermal at 190' c for 2 minutes, Det: 240°c, R268,540V, 455 nm LP, RC=ls, Att: 10x16, chart speed: 2.5 d m i n , holophotal channei, hydrogen: 200 mWmin, nitrogen: 30 rnL/min, air: 60 mL/min.

O 5 10 time (minutes)

O 5 10 time (minutes)

*The peaks are attributed to:

1. TBGe 2. TBSn 3. TBL

Fig 54. Chromatograms of the mixhne of 2 ng ferrocene, 500 pg nithenocene and 3.5 ng osmocene.

(A): with quariz chimney. (B): with PJass chimney.

GC conditions: Col: 120' C- 190' C ,1o0 Clmin, then isothennal at l9oo C for 2 minutes, Det: 240'~~ R268,540V, 455 nm LP, RC=ls, Att: 10x16, chart speed: 2.5 d m & holophotal chamel, hydrogen: 200 d/min, nitrogen: 30 ml/min, air: 60 mL/min.

time (minutes) O 5 10

tirne (minutes)

m e peaks are attributed to:

1. ferrocene 2. ruthenocene 3. osmocene

results are shown. It codd be seen that there wasn't any obvious difference.

A glas chimney was f h d y selected to do the simuitaueous detection of

derivatives of ùon (II) chloride tetrahydrate, rutheniun (III) chloride hydrate, osmium

containing compound, germanium 0 chloride, tin (IV) chloride and lead (11) niteaîe

with lithium cyclopenbdienylide and butylmagnesium chloride. The resuits are shown in

Fig 55, Fig 56, Fig 57 and Fig 58. Calibraiion curves for the simultaneous detection of

the above six inorganic species were pedormed and are shown in Fig 59.

Fig 55. Chromatograms conceming the derivatization of the mixture of l e d @) nitrate, tin 0 chloride and gtxmmiurn (IV) chlonde, kon (II) chloride tetrahydrate, Nthenium (III) chloride hydrate and

osmium containhg compomd by butyimagnesium chlonde and lithium cyclopentadienylide.

(A): 1.6 pL reagent blank. (B) 0.4 jiL sample.

GC conditions: Col: 120' C-190' C ,10'C/min, Det: 24ooc, R268,540V, 455 nm LP, RC=ls, An: 10x8, chart speed: 2.5 mm/min, holophotal channel, glass chimney, hydrogen: 190 &min, nitrogen: 30 mL/min, aK: 50 mL/&

O 5 10 tirne (minutes)

O 5 I O tirne (minutes)

* The peaks are attributed tu:

1. ferrocene 2. ruthenocene 3. osmocene 4. TBGe 5. TBSn 6. TBL

O 5 10 time (minutes)

O 5 10 time (minutes)

h e pab are attributal to:

1. ferrocene 2. ruthenocene 3. osmoane 4. TBGe 5. TBSn 6. TBL

Fig 56. Chromaîograms concerning the derivatization of the mixture of lead (II) nitrate, tin (IV) chloride and g d u m 0 chloride, ùon (II) chloride tetrahydrate, ruthenium (m) chioride hydrate and osmium containhg compound by butyimagnesium chioride and lithium cyclopentadienylide.

(C): 0.2 fi (1 0 ng) pure ferrocene + 0.4 pi, sample. 0): 0.2 & (1 ng) pure ruthenocene+ 0.4 pL sample -

GC conditions are the same as in Fig 55.

*The p a k s are amibutcd to:

1. ferrocene 2. ruthenocene 3. osmocene 4. TBGe 5. TBSn 6. TBL

tinte (minutes) time (minutes)

Fig 57. Chromatograms conceming the denvabtion of the mixture of lead (II) nitrate, tin (IV) chlonde and germanium (N) chloride, iron (II) chloride tetrahydrate, rutheniun (III) chlonde hydrate and osmium containing compound by butylmagnesium chloride and lithum cyclopentadienylide. (E): 0.3 pL (1.5 ng) pure osmocene + 0.4 pL sample. 0: 0.2 p L (2 ng) pure tetrabutylgermanium (TBGe)+ 0.4 pL sample.

GC conditions are the same as in Fig 55.

O 5 I O tirne (minutes)

O 5 10 time (minutes)

1. ferrocene 2. ruthenocene 3. osmocene 4. TBGe 5. TBSn 6. TBL

Fig 58 . Chromatograms conceming the denvatkation of the mixture of lead (II) nitrate, tin 0 chloride and gemianium 0 chionde, iron (II) chloride tetrahydrate, mthenium (III) chloride hydrate and osmium containing compound by butyimapnesium chloride and lithum cyclopentadienylide. (G): 0.2 pL (1 ng) pure tetrabutyItin (TBSn) + 0.4pL sample (H): 0.2 pL (10 ng) pure tetrabuîy11ead (TBL)+ 0.4 pi, sample.

GC conditions are the same as in Fig 55.

log (inorganic species (ng))

Fig 59. Calibration curves fbr the sirnultaneous detection of germanium (N) chloride, tin(N) chloride, lead (II) nitrate, iron (II) chloride tetrahydrate, Naienium (III) chloride hydrata and osmium containing compound.

- 1. germanium (N) chloride. 2. tin (IV) chloride. 3. lead (II) nitrate. 4. iron (II) chloride tetrahydrate. 5. nithenium (III) chloride hydrate. 6. osmium containing chloride.

CHAPTER 6

CONCLUSIONS AND SUGGESTIONS

Derivatization is an important method to widen the application of GC. In this

thesis, inorganic lead (II) species was derivatized with sodium tetraethylborate and

detected with FPD. The detection limit codd mach 1 ppb. Inorganic iron group species

were derivahd, first individually then simuitaneously with lithium cyclopentadienylide.

By comparing the retention thne of the derivahd product with that of pure

compouads, as well as by checkhg the CO-injection red ts , it was s h o w that

denvatization was successful. Similady, iron (II) chioride tetrahydrate, rutheniurn (III)

chloride hydrate, osmium containing compound, germanium (IV) chloride, tin (Iv)

chloride and lead (II) nitrate were simdtaneously denvatized with lithium

cyclopentadienylide and butylmagnesium chloride. The detection limit for the

detennination of ruthenium is 300 pg/mL, which is better than 70 ng/mL reported in a

recent reference '''I.

MIP-AED and ICP are general methods to do mdti-element detennination. The

advantage of them is that they could be directly used in aqueous determination of

elements, however, high cost of hstruments is their common drawback.

Denvatization-GC combination is a method which is much cheaper, but the disadvantage

is the diniculty to be applied in aqueous phase.

99

Even though some basic studies were performed in this thesis, there are still many

other denvatization methodologies which would be interesthg to investigate. Accordhg

to Khuhawar and Memon trifluoroacetylacetone and ethylenediamine were used to

denvatize vanadium, palladium, and copper, the derivatized products were analyzed by

GC-FID. Since smdl flame photometric detector is very sensitive to transition elements,

it is possible that these elements could be detected after being denvatized by the above

methodology .

Some carbonyl compounds showed very good response in FPD. If by some

reactions metals are converted to carbonyls, the number of elements which could be

detected by GC-FPD would be M e r increased.

APPENDIX

DEFINITIONS FOR SOME SPECIFIC

TERMS USED IN THIS THESIS

2. Detection limit:

It is a unit which is usually used in the detection of the

spectnim. The definition is:

Coulombs peak arealmole d y t e injected.

unit varies in different context. In the FPD, moldsec in log

scde is used to compare different detectabilities. For practical

analysis of samples in solution, ppm ( part per million, about

1 mglL ) and ppb @art per billion, about l ug/L) are

sometimes used in order to aliow cornparison with the

literature .

no unit. S: signal, N , : peak-peak noise.

no unit, it is obtained fiom the amount ratio of the analyte

and the intelference with same signal to noise ratio.

unit varies with different context In FPD, molelsec is I

sometimes used which is obtained by using mole anaiyte

injected over the half width of the beak in seconds.

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