Determination of sulfa antibiotic residues in river and particulate matter by field-amplified sample injection-capillary zone electrophoresis.

In the present research, field-amplified sample injection-capillary zone electrophoresis (FASI-CZE) coupled with a diode array detector was established to determine trace level sulfa antibiotic. Sulfathiazole, Sulfadiazine, Sulfamethazine, Sulfadimethoxine, Sulfamethoxazole, and Sulfisoxazole were selected as analytes for the experiments. The background electrolyte solution consisted of 70.0 mmol/L borax and 60.0 mmol/L boric acid (including 10% methanol, pH 9.1). The plug was 2.5 mmol/L borax, which was injected into the capillary at a pressure of 0.5 psi for 5s. Then the sample was injected into the capillary at an injection voltage of -10 kV for 20s. The electrophoretic separation was carried out under a voltage of +19 kV. The capillary temperature was maintained at 20 ˚C throughout the analysis, and six sulfonamides were completely separated within 35 min. Compared with pressure injection-capillary zone electrophoresis, the sensitivity of FASI-CZE was increased by 6.25-10.0 times, and the limits of detection was reduced from 0.2-0.5 μg/mL to 0.02-0.05 μg/mL. The method was applied to the determination of sulfonamides in river water and particulate matter samples. The recoveries were 78.59-106.59%. The Intra-day and Inter-day precisions were 2.89-7.35% and 2.77-7.09%, respectively. This provides a simpler and faster method for the analysis of sulfa antibiotic residues in environmental samples. This article is protected by copyright. All rights reserved.