Development of an analytical method for determination of sulfamethoxazole residues using derivation with thiobarbituric acid

Abstract

Introduction: Developing an analytical method is an important issue in quality control of pharmaceutical and food sciences. Determination of drug residuals in animal products such as milk is one of the important issues in the quality of food related audits. Sulfamethoxazole is a common antibiotics used in animals for prevention of bacterial contaimination . therefor, determination of residues in animal product is of great important from safety point of view.. Objective: The aim of this study was to optimize the effective factors in the reaction of sulfamethoxazole with thiobarbituric acid (TBA) from milk and suggest a new analytical method for determination of its content in milk samples. Methods: The effective reaction factors were optimized then the milk sample containing sulfamethoxazole was mixed with acetonitrile in a 1:1 ratio and centrifuged and the supernatant was collected. The reaction of the extracted sample with TBA produced a colored compound in the optimized condition that was detected by UV-Vis spectrophotometry at 530 nm. Results: Based on the obtained results, temperature and time for reaction between sulfamethoxazole and TBA were set to 80 °C and 24 h, respectively. Moreover, volume of TBA from stock solution (35.5 mM) and hydrochloric acid with concentration of 0.1 mmol were selected as the optimal condition. After method validation under the optimum conditions, the method provided a linear range (0.75-20 mg/L) with a coefficient of determination (R2) of 0.99 and acceptable accuracy and precision. Conclusion: A new, efficient and simple analytical method based on reaction between sulfamethoxazole and TBA was developed and validation results showed acceptable accuracy and precision to measure sulfamethoxazole in milk simples.