Determination of erythromycin in rat plasma with capillary electrophoresis-electrochemiluminescence detection of tris(2,2′-bipyridyl) ruthenium(II)

A fast and sensitive approach for determination of erythromycin in rat plasma was described. The method used capillary electrophoresis coupled with end-column electrochemiluminescence (ECL) detection of Ru(bpy)32+. The separation column used had an inner diameter of 75 μm. The running buffer was 15 mmol/L sodium phosphate (pH = 7.5). The solution in the detection cell was 50 mmol/L sodium phosphate (pH = 8.0) and 5 mmol/L Ru(bpy)32+. ECL intensity varied linearly with erythromycin concentration from 1.0 ng/mL to 10 μg/mL. The detection limit (S/N = 3) was 0.35 ng/mL. The relative standard deviations, of ECL intensity and migration time for eight consecutive injections of 1.0 μg/mL erythromycin (n = 8), were 1.3% and 1.8%, respectively. The method was successfully applied to erythromycin determination in rat plasma. The recovery ranged from 92.5 to 97.5%.