Simultaneous determination of isoniazid and p-aminosalicylic acid by capillary electrophoresis using chemiluminescence detection

It was found that isoniazid (ISO) or p-aminosalicylic acid (PAS) could enhance the chemiluminescence (CL) emission from Cu (II)-luminol-hydrogen peroxide system, and the increased chemiluminescence signals were proportional to their concentrations, respectively. Based on this phenomenon, a chemiluminescence method coupled to capillary electrophoresis (CE) was established for simultaneous determination of ISO and PAS. The CE conditions including running buffer and running voltage were investigated in detail. The effects of the pH of H2O2 solution and the concentrations of luminol, H2O2 and Cu (II) on the CL signal were also investigated carefully. Under the optimized conditions, the analysis could be accomplished within 10 min, with the limits of detection of 0.3 mu g mL(-1) for ISO and 1.1 mu g mL(-1) for PAS, corresponding to 7.2 and 26.4 pg per injection (24 nL), respectively. Finally, the method was validated by determining the two analytes in pharmaceutical preparation and spiked human serum samples. The results of pharmaceutical tablet analysis were in good agreement with the labeled amounts. The recoveries for ISO and PAS in human serum were in the range of 92-104% and 90-113%, respectively. Copyright Q 2009 John Wiley & Sons, Ltd.