Analytical Method for Residual Oxytetracycline in Livestock and Marine Products

An analytical method for residual oxytetracycline (OTC) in livestock and marine products was evaluated. OTC was extracted from a sample with McIlvaine buffer (pH 4.0) containing 0.01mol/L EDTA-2 Na. The extract was washed with hexane, followed by a Sep-Pak Plus PS2 cartridge clean-up procedure. OTC was determined by HPLC. The results obtained by HPLC were well correlated with those of a microbioassay method. The average recovery at the tolerance limit levels established by the Food Sanitation Law of Japan was 90.4% and the determination limits were 0.02ppm (muscle, seafood, milk), 0.04ppm (liver, kidney, egg) and 0.002ppm (fat).