Microchip capillary electrophoresis/electrochemical detection of hydrazine compounds at a cobalt phthalocyanine modified electrochemical detector

This article reports on the use of cobalt(II) phthalocyanine (CoPc)-modified carbon paste amperometric detector for monitoring hydrazine compounds following their microchip separation. The marked catalytic electrochemical properties of CoPc-modified electrode display enhanced sensitivity compared with unmodified carbon pastes at a relatively low detection potential (+0.5 V versus Ag/AgCl). Factors influencing the on-chip separation and detection processes have been optimized. Three hydrazines (hydrazine, 1,1 dimethylhydrazine, and phenylhydrazine) have been separated within 130 s at a separation voltage of 1 kV using a 10 mM phosphate run buffer (pH 6.5). The detection limits obtained from using the CoPc-modified carbon paste electrodes for hydrazine and phenylhydrazine are 0.5 and 0.7 μM, respectively, with linearity over the 20-200 μM range examined. Such miniaturization and speed advantages of microchip CE are coupled to the highly sensitivity and convenient preparation of CoPc-modified carbon paste electrode. The resulting microsystem should be attractive for field monitoring of toxic hydrazine compounds in environmental applications.