Determinação de sulfato de estreptomicina em amostras de medicamentos veterinários por análise em fluxo

Abstract

This work describes a flow analysis system for the determination of streptomycin in veterinary medicines samples. The method is based on alkaline hydrolysis of streptomycin followed by reaction with produced guanidine ions with iron (II) forming a colored compound that is detected spectrophotometrically at a wavelength of 520 nm. To assess the effects, both chemical factors as the flow, we performed a screening using fractional factorial design of two levels.To obtain the optimal values, one Doehlert Planning Matrix was made. The linear response range was 60 mg L-1 to 1500 mg L-1, the analytical curve equation: Abs = 0.011 + 4.721x10-4 (L mg-1) streptomycin, with a correlation coefficient of 0.9874. The limits of detection and quantification were 18 mg L-1 and 63 mg L-1 respectively, the reading frequency was 30 samples per hour. As to the selectivity of the method, we tested the influence of the major concomitant of veterinary drugs and these showed no significant interference. Samples of veterinary drugs were diluted and only inserted into the FIA system for the determination. The accuracy was verified applying the method of comparison, four samples of the line veterinary medicines were analyzed and the results were consistent concentration of streptomycin (t-test, p = 0.05), with the ones obtained with the method of High Performance Liquid Chromatography (HPLC).