Determination of Effective Ingredients in Compound Sulfamethoxazole Tablets by Capillary Electrophoresis with Amperometric Detection

A high-performance capillary electrophoresis with amperometric detection (CE-AD) method has been used for the determination of three antibacterial sulfa components, sulfamethoxazole (SMZ), sulfadiazine (SD) and trimethoprim (TMP). The effects of several factors on CE-AD were investigated. Under the optimum conditions, the three components could be separated well within 14 min in a 70-cm length capillary at the separation voltage of 18 kV, injection time of 6 s in a 13-mM borax-18 mM potassium dihydrogen phosphate running buffer (pH 5.8). The above three analytes have good linear relationship between peak current and concentration of analytes in the range of 5 × 10−4−5 × 10 −2 g l−1, 5 × 10−4−1 × 10−1 g l−1, and 5 × 10−4−5 × 10−2 g l−1, respectively, and the detection limits (S/N = 3) ranged from 8.0 × 10−5 to 5.1 × 10−5 g l−1 for all analytes. This proposed method has been successfully applied for the determination of the main effective components in Compound Sulfamethoxazole Tablets.