Determination of Clindamycin in Its Capsules and in Human Urine by Capillary Electrophoresis-Electrochemiluminescence

Based on the enhancing effect on the electrochemiluminescence (ECL) of the complex tris-(2,2′-bipyridyl) ruthenium abbreviated as Ru(bpy)2+3 by clindamycin,and by combining the capillary electrophoresis (CE),an efficient method of separation,with the ECL,a highly sensitive method of detection,contents of clindamycin in its capsules and in samples of human urine were determined effectively by CE-ECL.Through systematic study on the conditions of separation by CE and on the ECL reaction,optimum conditions were found as follow: ① concn.of Ru(bpy)2+3: 5 mmol·L-1;② potential of detection: 1.15 V;③ concn.of PBS in ECL cell: 50 mmol·L-1;④ pH value of PBS in detection cell: pH 7.5;⑤ voltage of sample introduction: 10 kV;⑥ time of sample introduction: 10 s.Linear relationship between values of detection signals and concentration of clindamycin was obtained in the range of 5.0×10-7-1.0×10-4mol·L-1.Detection limit (3S/N) found was 1.4×10-7mol·L-1.Under the optimum condition,analysis of a sample of the capsule or the human urine was completed within 4 min.