zone fluidics for marine trace metal analysis · 2013-04-03 · what is zone fluidics? zone...
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What is Zone Fluidics? Zone Fluidics Hardware
Cassie Schwangera, Graham Marshallb, and Jay Cullena
a University of Victoria, Vancouver Island, B.C., Canada b Global FIA, Fox Island, WA, USA
Zone Fluidics for Marine Trace Metal Analysis
Aboard the CCGS John P Tully
Copper Determination Iron Measurement Silver Extraction and Detection
Samples were collected at various depths from 15-800m from the John P Tully CCGS
Vessel in February 2011 along the Line P transect at stations P4, P12, P16, P20 and
P26. Some measurements were carried out on board and all samples were acidified
for subsequence shore analysis.
A prototype Global FIA FloPro™ ZF analyzer was used for ship-board measurements in
the course of this cruise. The following lessons were learned with respect to instrument
design for ship-board instrumentation:
1. A compact instrument with a small footprint is needed because of space constraints.
2. Tie-downs are needed to stabilize the instrument when underway in rough seas.
3. A spares kit containing vulnerable and key components is needed for on-board
repairs. ZF’s modular design supports field replacement and repair of components.
4. A simple interface is needed to allow sample extraction without contamination from
the sample bottles as well as sampling from a towed pumping system.
5. Pre-cruise preparation of reagents is preferred. Low reagent usage, which is a key
characteristic of ZF, reduces the volume of reagents that have to be carried aboard.
Typical ZF reagent use varies between ten and a few hundred µL per measurement.
6. Unattended measurement from an auto sampler allows ongoing measurement at
night, during sampling, and while the vessel is underway.
7. Assays employed must be well-characterized and stable.
8. ZF allows automation of solvent extraction and solid phase enrichment sample prep
as well as repeatable spectrophotometric and chemiluminescence measurement.
Fittings and
tubing
Membrane sampling
device
LED and tungsten
light sources
Mini-columns
Pumps Valves
Chemiluminescence
Dissolved gas sampling
Detector flow cells
Self cleaning filter
Sampling probe and filter tips
uv-vis spectrometry
Electrochemistry
Customized systems
Copper Chemiluminescence Determination (after the method of Zamzow et al.2)
1. A 1,10 phenanthroline solution and H2O2 are aspirated and mixed in the holding coil.
2. The 0.02M nitric acid back extraction raffinate or acidified sea water sample is mixed
with the chemiluminescence reagent zone by merging the solutions via the mixing
tee and then the product is pumped through the flow cell.
3. The chemiluminescence profile is captured and the peak area and peak height are
determine and related to concentration by means of calibration.
Abs = 10801[Cu, nm] + 18228 r² = 0.998
0.00E+00
1.00E+04
2.00E+04
3.00E+04
4.00E+04
5.00E+04
6.00E+04
7.00E+04
0 1 2 3 4
Pe
ak H
eig
ht
- C
ou
nts
Copper (nM)
Copper (Cu)
Extraction (based on the manual method of Miller and Bruland3) 1. An acidified seawater sample is mixed with a buffer and ligand solution. 2. This mixture plus chloroform are dispensed into the extraction shaker. 3. The shaker is energized and the metal-ligand is extracted into the CCl4. 4. After shaking, the mixed-phase solution is dispensed to a collection vial
where it separates into two phases. The aqueous layer is discarded. 5. The CCl4 layer is acidified. 6. The analyte is back-extracted into the acidic phase which is recovered and
the depleted CCl4 phase is discarded.
Colorimetric method (unpublished method developed at U. Vic.)
1. The acidified raffinate from the extraction is mixed with a 1,10-phenanthroline and
gallocyanine solution. 2. The solution is heated in the ZF manifold for approximately 3 min at 40⁰C.
3. The reaction mixture is subsequently measured photometrically at 540nm. The
presence of Ag causes a decrease in signal resulting in a calibration curve with
negative slope (Abs=-0.082[Ag (µm)]+1.548, r2=0.993.
From an operational point of view, Zone Fluidics1 (ZF) is an approach to sample
handling where a zone or zones of fluid are shuttled between and within an assembly of
one or more unit operations where different sample processing steps are performed.
Where FIA and SIA focus on dispersion, ZF borrows from these techniques and many
others, and focuses attention on what we do to the sample and other zones in the
fluidics manifold to transform the analyte into a detectable species. Where appropriate,
judicious use of air bubbles and immiscible solvent zones are used to facilitate mixing
and other sample manipulation operations.
This approach to flow-based analysis is found to significantly expand the scope and
extent of automated sample manipulations. ZF becomes a general-purpose fluid
handling tool, allowing the precise manipulation of gases, liquids and solids to
accomplish complex sample prep and analytical manipulations with relatively simple
hardware. Examples of unit operations include sample manipulation steps for
• enriching,
• solvent extracting,
• exchanging media,
• sample filtering,
• diluting
• headspace sampling,
• matrix modifying,
• de-bubbling,
• distilling,
• digesting (thermal, uv
and chemical)
• amplifying,
• hybridizing, and
• reacting.
In current analytical practice many of these steps are handled manually prior to analysis
or in separate pieces of equipment. In ZF, the sample zone is subjected to these unit
operations in a sequential (and sometimes parallel) manner while being transported
within or from one unit operation to the next under fluidic control.
ZF offers an alternative approach to automation whereby unit operations are performed
in narrow bore conduits. ZF also makes use of concepts employed in robotics where
samples are carried from one workstation to the next. In a sense, ZF is a sort of fluidics
robot which transports a sample via tubing conduits rather than via a mechanical arm.
ZF is difficult to use efficiently without modular and hierarchical device control software. FloZF is a versatile device control and data acquisition program for controlling ZF instrumentation.
Established measurement chemistries4 for iron enrichment and analysis are being
adapted to ZF using the manifold depicted above. The preferred eluent is
prepositioned in the eluent holding coil (EHC). Then sample is drawn over the
enrichment column (EC). After enrichment, the eluent is drawn over the column and
carries the concentrated iron to the holding coil (HC) where it is bracketed between
bubbles and stacked with zones of buffer, peroxide, and luminol. This reaction mixture
is then transported to the GloCel chemiluminescence (CL) detector. En-route the
reactants are mixed under Taylor flow conditions.
Reservoirs
SV-A SV-B HC
PRV C
W
SP
CL
P
EC
EHC
References
1. Graham Marshall, Duane Wolcott, and Don Olson, Zone Fluidics In Flow Analysis: Potentialities and Applications, Anal. Chim. Acta, 2003, 499, 29-40
2. Heidi Zamzow, Kenneth Coale, Kenneth Johnson, and Carole Skamoto, Determination of copper complexation in seawater using flow injection analysis
with chemiluminescence detection, Anal. Chim. Acta,1998, 377, pp.133-144
3. Lisa Miller, Kenneth Bruland, Organic speciation of silver in marine waters, Environ. Sci. Technol., 1995 26 pp. 2616-2621
4. Kenneth Johnson, Virginia Elrod, Steve Fitzwater, Joshua Plant, Francisco Chavez, Sara Tanner, Michael Gordon, Douglas Westphal, Kevin Perry,
Jingfeng Wu, and David Karl Surface ocean-lower atmosphere interactions in the NE Pacific Ocean Gyre: Aerosols, iron, and the ecosystem response,
Global Biogeochem Cycles, 2003, 17(2), pp. 32-1 – 32-14
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