Capillary Electrophoresis Chips with Thick-Film Amperometric Detectors: Separation and Detection of Hydrazine Compounds

Abstract

A miniaturized analytical system for separating and detecting toxic hydrazine compounds, based on the coupling of micromachined capillary electrophoresis (CE) chips with removable thick-film amperometric detectors is described. The study also represents the first example of using a chemically modified electrode for microchip CE applications. The microsystem with the electrocatalytic palladium-deposited detector offers a rapid (2 min) low-potential (+0.5 V vs. Ag/AgCl) simultaneous detection of hydrazine, methylhydrazine, dimethylhydrazine, and phenylhydrazine. Such compounds could be detected down to the 1.5×10–6 M level, with linearity over the 2×10–5 M–2×10–4 M range examined. While the concept of miniaturized separation/detection systems is presented within the framework of hydrazine compounds, such devices should be attractive for field monitoring of other classes of toxic contaminants. The design of the microsystem permits rapid replacement of the detector strip and a convenient surface modification (in a separate, optimal cell). The development of fast-responding miniaturized systems, with negligible waste production, holds particular promise for meeting the requirements of field ‘Green Analytical Chemistry’.