Powder microelectrodes for capillary electrophoresis with amperometric detection

In this paper, we first report the use of powder microelectrodes (PMEs) as the amperometric detector for thiols, hydrazine and hydroxylamine in capillary electrophoresis (CE). This PME, with graphite-supported metalloporphyrin powder as catalyst, offers a few advantages as an amperometric detector in CE. Concentration limit of detection and mass limit of detection obtained for L-cysteine at the PME could reach 88 nM and 230 amol, respectively. The response of thiols at the PME was very reproducible since the electrode fouling was reduced. A relative standard deviation of peak heights (n = 8) of 1.8% and a relative standard deviation of migration time (n = 8) of 1.0% can be obtained for L-cysteine. The material packed in the PME can easily be changed. Hence, it is very convenient to choose suitable catalysts to detect special analytes, and this specially designed microelectrode should be applicable to many other compounds of biological interest.