Determination of tulathromycin in swine tissues by Liquid chromatography-tandem mass spectrometry

A liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for determination of tulathromycin in swine tissues has been developed. Prior to the instrumental analysis, the sample preparation technique involved extraction with a solution of meta-phosphoric acid followed by solid-phase extraction clean-up using a polymeric mixed-mode strong cation-exchange sorbent. The chromatographic separation was performed on a C8 chromatographic column with a gradient elution mode. Mass spectral acquisition was performed in selective multiple reaction monitoring mode by using a triple quadrupole mass spectrometer. The method has been characterized by providing the parameters of precision, accuracy, specificity, decision limit (CC alpha) and detection capability (CC beta) according to the Commission Decision 2002/657/CE. The calibration curves were linear in the range of 10-9000 mu g kg(-1). The recoveries ranged from 92.9% to 102.1%. The repeatability was below 8.0% and the within-laboratory reproducibility was lower than 9.2%. The limits of detection ranged from 2 to 4 mu g kg(-1) and the limit of quantification was 10 mu g kg(-1). The presented analytical method can be used for measuring the tulathromycin depletion in swine tissues (kidney, liver and muscle) over time.