One-step liquid chromatographic method for the determination of oxytetracycline in fish muscle

A one-step simple and rapid high performance liquid chromatography (HPLC) method was developed for the determination of oxytetracycline (OTC) in fish tissue. The method involves liquid extraction of muscle tissue, precipitation of proteins and reversed phase HPLC analysis with spectrophotometric detection. The limit of quantitation of OTC in spiked fish muscle was 0.04 μg/g and the method showed high linearity (r2 = >0.999) in the working range of 0.04–2 μg/g. The precision (%R.S.D.) was between 1.9 and 7.5% for the concentration range 0.04–1.0 μg/g and there was no significant difference between the concentrations determined on three different test days for all four spiked concentrations. The percentage recovery over the spiked concentration range 0.04–1.0 μg/g was consistently within a narrow range of 33–35%. While the method had the advantage of high precision, sensitivity and linearity, the methodʹs additional salient advantages included high sample through-put (60 individual preparations per day) and minimum amount of consumables, time and labour required to perform the analysis. The method was successfully applied to a pharmacokinetic study.