Determination of reserpine in urine by capillary electrophoresis with electrochemiluminescence detection

A fast and sensitive approach to detect reserpine in urine using micellar electrokinetic capillary chromatography with electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) detection is described. Using a 25 mum i.d. capillary as separation column, the ECL detector was coupled to the capillary in the absence of an electric field decoupler. Field-amplified injection was used to minimize the effect of ionic strength in the sample and to achieve high sensitivity. In this way, the sample was analyzed directly without any pretreatment. The method was validated for reserpine in the urine over the range of 1 x 10(-6) - 1 x 10(-4) mol/L with a correlation coefficient of 0.996. The RSD for reserpine at a level of 5 mumol/L was 4.3%. The LOD (S/N = 3) was estimated to be 7.0 x 10(-8) mol/L. The average recoveries for 10 mumol/L reserpine spiked in human urine were 94%.