Capillary electrophoresis microchips with thick-film amperometric detectors: separation and detection of phenolic compounds

Abstract

A miniaturized analytical system for separating and detecting toxic phenolic compounds, based on the coupling of a micromachined capillary electrophoresis (CE) chip with a thick-film amperometric detector is described. The integrated microsystem offers a rapid (4 min) simultaneous measurement of seven priority chlorophenolic pollutants. Such compounds could be detected down to the 1×10 −6–2×10 −6 M level, with linearity up to the 2×10 −4 M level examined. The highly stable response observed for repetitive injections (R.S.D.=3.7%, n=20) reflects the negligible surface passivation due to the injection of extremely small sample volumes. Additional phenols were separated and detected upon raising the pH of the running buffer from 8.0 to 10.5. Applicability to river water samples is demonstrated. While the concept of miniaturized separation/detection systems is presented within the framework of phenolic contaminants, such devices should be attractive for field monitoring of other classes of priority contaminants. The development of fast-responding miniaturized systems with negligible waste production holds particular promise for meeting the requirements of field ‘Green Analytical Chemistry’.