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