Separation and detection of nitrophenols at capillary electrophoresis microchips with amperometric detection

A miniaturized analytical system for the separation and amperometric detection of toxic nitrophenols, based on the coupling of a micromachined capillary electrophoresis (CE) chip with a glassy carbon detector is described. This microsystem enables a rapid (120 s/sample) simultaneous determination of five priority nitrophenolic pollutants (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 2-methyl-4,6-dinitrophenol). These compounds can be detected down to the 1 × 10^-5 M level using a 15 mM phosphate buffer pH 7.2 (containing 1.3 mM α-cyclodextrin) as running solution on 77 mm long microchannel by applying a separation voltage of 3000 V and a negative potential of -0.7 V (vs. Ag /AgCl wire). Applicability to ground water samples was demonstrated.