Multiplexed Colorimetric Solid-Phase Extraction:  Determination of Silver(I), Nickel(II), and Sample pH

This paper reports the design and ground-based testing of a multiplexed colorimetric solid-phase extraction (MC-SPE) platform for the rapid determination of multiple water quality parameters in a simple set of operational steps. Colorimetric solid-phase extraction (C-SPE) is an analytical platform t...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2004-08, Vol.76 (16), p.4881-4887
Main Authors: Gazda, Daniel B, Fritz, James S, Porter, Marc D
Format: Article
Language:English
Subjects:
Analytical chemistry
Chemistry
Design
Exact sciences and technology
Nickel
Samples
Silver
Solids
Spectrometric and optical methods
Tests
Water quality
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Summary:This paper reports the design and ground-based testing of a multiplexed colorimetric solid-phase extraction (MC-SPE) platform for the rapid determination of multiple water quality parameters in a simple set of operational steps. Colorimetric solid-phase extraction (C-SPE) is an analytical platform that combines impregnated colorimetric reagents on a solid-phase extraction membrane and diffuse reflectance spectroscopy to quantify trace analytes in water. In extending C-SPE to MC-SPE, a filter holder that incorporates discrete analysis channels and a jig that facilitates the concurrent operation of multiple syringes have been designed, enabling the simultaneous determination of three different measures of water quality. Separate, single-parameter membranes, placed in a readout cartridge create unique, parameter-specific addresses at the exit of each channel. Following sample exposure, the diffuse reflectance spectrum of each address is collected serially and the Kubelka−Munk function is used to quantify each water quality parameter via calibration curves. Performance evaluations of the MC-SPE platform were conducted using sample pH, silver(I), and nickel(II). Determinations of silver(I) (0.05−0.5 ppm) and nickel(II) (1.8−5.0 ppm) follow established C-SPE methods on reversed-phase extraction membranes using 5-(p-dimethylaminobenzylidene)rhodanine and dimethylglyoxime, respectively, as colorimetric reagents. Sample pH (2.5−5.0) is measured using an anion-exchange membrane impregnated with fluorescein. These determinations require ∼120 s to complete using a total sample volume of 3.0 mL. The extension of MC-SPE to the determination of a greater number of analytes and its potential application to space and earth-bound monitoring needs are briefly discussed.
ISSN:0003-2700
1520-6882
DOI:10.1021/ac049449r