A novel method for determination of Tetracycline and its metabolite residues in cow milk

A simple, sensitive and inexpensive method was developed using matrix solid-phase dispersion (MSPD), together with high performance liquid chromatographic method for determination of Tetracycline residues and its metabolite 4-Epitetracycline in cow milk. The evaluated parameters included the type and amount of sorbent (silica gel, C18 and alumina) and the nature of eluent (20% trichloro acetic acid, 0.01M citric acid, 0.01M disodium hydrogen phosphate, 0.01M EDTA and Methanol). The best results were obtained using 10 mL of milk sample, 1.0 g of C18 as sorbent and 20mL of 20% trichloroacetic acid, 0.01M citric acid, 0.01M disodium hydrogen phosphate, 0.01M EDTA and Methanol (1:2:2:2:3, (v/v)).The method was validated using in milk samples spiked with Tetracycline residues and its metabolite 4-Epitetracycline at different concentration levels (0.05 and 0.5 μg/mL). Average recoveries (using each concentration six replicates) ranged 87–96%, with relative standard deviations less than 2%, calibration solutions concentration in the range 0.05–5.0 μg/mL and limit of detection (LOD) and limit of quantification (LOQ) were 0.02 μg/mL and 0.05 μg/mL respectively.