Determination of sulpiride by capillary electrophoresis with end-column electrogenerated chemiluminescence detection

BACKGROUND: Capillary electrophoresis (CE) with tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3(2+)]-electrogenerated chemiluminescence (ECL) detection is a promising method for clinical analysis. In this study, a method combining CE with Ru(bpy)3(2+) ECL (CE-ECL) detection that can be applied to amine-containing clinical species was developed, and the performance of CE-ECL as a quantitative method for determination of sulpiride in human plasma or urine was evaluated. METHODS: Sulpiride was separated by capillary zone electrophoresis in uncoated fused-silica capillaries [50 cm x 25 microm (i.d.)] filled with phosphate buffer (pH 8.0) and a driving voltage of +15 kV, with end-column Ru(bpy)3(2+) ECL detection. A platinum disc electrode was used as working electrode. Sulpiride in human plasma or urine samples (100 microL) was extracted by a double-step liquid-liquid extraction procedure, dried under nitrogen at 35 degrees C in a water bath, and reconstituted with 100 microL of filtered water. The extraction solvent was ethyl acetate-dichloromethane (5:1 by volume). RESULTS: Under optimum conditions (pH 8.0 phosphate buffer, injection for 6 s at 10 kV, and +1.2 V as detection potential), separation of sulpiride was accomplished within 4 min. The calibration curve was linear over a concentration range of 0.05-25.0 micromol/L, and the limit of detection was 2.9 x 10(-8) mol/L for sulpiride. Intra- and interday CVs for ECL intensities were <6%. Extraction recoveries of sulpiride were 95.6-101% with CVs of 2.9-6.0%. The method was clinically validated for patient plasma and urine samples. CONCLUSIONS: CE combined with Ru(bpy)3(2+) ECL is reproducible, precise, selective, and enables the analysis of sulpiride in human plasma and urine. It thus is of value for rapid and efficient analysis of amine-containing analytes of clinical interest.