Dr. John Driscoll PID Analyzers, LLC

2 Washington Circle Sandwich, MA 02563

Paper #2340-14 Booth # 2080

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Detection of Low ppb Levels of Chlorinated HC by GC-PID (11.7)

A number of GC detectors have been used for the analysis of chlorinated hvdrocarbons (Cl HC) in environmental samples. Man have been found unsatisfactory

The problems have included: complexity, low response factors, poor detection limits, significant variation with the degree of unsaturation, limited selectivity…

The PID does not solve all of the above problems but it is easy to use, has ppb detection limits and the response does not vary widely with structure

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Detectors for Cl HC have depended upon the following principals:

A. electron absorbing properties- ECD B. decomposition in furnace & detection of H+-

ElCD C. thermionic emission in a flame- Cl-

D. photoionization detection (PID) with a 10.2/10.6 lamp

Each of these detectors have their limitations In this paper, we will discuss the use of a PID

with an 11.7 eV lamp that will solve some of the previous detector limitations

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Detector Det Limit Limitation

ECD low pg

structure, licensing, operation , easy to saturate

ElCD low ppm conc, furnace, concentrator is required for ppb levels

Alkali Flame mid ppm conc, reliability, specificity

PID 10.6 low pg specificity

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Name IP eV 10.6eV Response 11.7 eV Response

Chloroform 11.42 0 3.15

Carbon tetrachloride 11.47 0 4.22

Chloroethanol 0.20 6.70

Methylene chloride 11.35 0.14 6.83

Methyl chloride 11.28 0 7.60

Vinyl chloride 10.00 3.20 7.80

1, 1, 2, 2-tetrachloroethane 11.10 0 8.60

Dichloromethane 11.35 0 8.70

Ethyl chloride 0 9.20

Epichlorohydrin 10.60 0.70 10.30

Ethylene dichloride 11.00 0 10.50

1, 1, 1-trichloroethane 11.25 0 10.70

Allyl chloride 10.20 1.30 11.90

1, 3-dichloropropane 10.85 0.20 12.10

1, 2-dichloropropane 10.87 0.20 12.10

o-dichlorobenzene 9.07 11.90 15.50

m-dichlorobenzene 9.12 11.90 15.50 10

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y = 6.0204x + 2100.5

0

50000

100000

150000

200000

250000

300000

350000

0 10000 20000 30000 40000 50000 60000

PH fo

r 11.

7 PI

D

ppb CHCl3

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SENSITIVITY wo PRECONCENTRATION PID 10.6 eV- need unsaturation- low ppb

detection PID 11.7 eV sub ppm detection ECD-needs multiple Cl to achieve low level

detection- MeCl2 example ElCD PPM- need oven to decompose- low

ppm min det. Requires concentrator for ppb

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# of Cl ECD PID 11.7

1 5 62

2 30 65

3 100 70

4 600 80

5 5000 85

6 40000 100

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y = 0.2678e1.956x

y = 7.5x + 48.333

0

1000

2000

3000

4000

5000

6000

0 2 4 6

Series1

Series2

Expon. (Series1)

Linear (Series2)

chlorobenzenes

Name Conc ppb

Height % Area % Time

1 TCE 500 973374 40.29 312042784 43.14 1:04

2 PCE 500 746159 30.88 228910192 31.65 1:34

3 TCB 500 664208 27.49 173209056 23.95 2:07

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-200000

0

200000

400000

600000

800000

1000000

1200000

0:00 1:40 3:20 5:00 6:40 8:20 10:00min

1

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The 11.7 PID is very useful for low MW HC such as CHCl3, CCl4, CH2Cl2, CH3Cl etc. Detection limits for CHCl3 were found to be 50 ppb for 0.5 cc sample

For the chlorinated HC with double bonds the PID with a 10.6 eV lamp, the detection limit is 1-2 ppb

The PID is one of the most sensitive detectors for Cl HC and a wide range of compounds can be detected with the 10.6 & 11.7 eV lamps

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