A single LC‐MS/MS validated method for tulathromycin quantification in plasma, seminal plasma, and urine to be applied in a pharmacokinetic study in bull

Abstract

Tulathromycin is a macrolide antibiotic generally used for the treatment of respiratory diseases in cattle and swine. This work proposes an improvement of a previously published LC-MS/MS method for tulathromycin determination in pig serum, here validated in three different bull matrices: plasma, seminal plasma, and urine. The approach is based on a quick protein precipitation with acetonitrile, filtration, and sample dilution before injection, allowing to rapidly process large batches of samples.Analytes separation was obtained using a BEH C18 (50 Â 2.1 mm, 1.7 μm) column, maintained at 40 C with a chromatographic run of 5 min. The method was fully validated over concentration ranges suitable for field levels of tulathromycin found in each matrix (0.01-1 μg/ml for plasma, 0.05-5 μg/ml for seminal plasma, and 0.1-10 μg/ml for urine), showing good linearity during each day of testing (R 2 always >0.99). Accuracy and precision were within ±15% at all QC concentrations in all the three matrices. Furthermore, the use of tulathromycine-d7 as internal standard mitigated the potential impacts of matrix effect. The validated technique was successfully applied to samples collected during a pharmacokinetic study in bulls, allowing to monitor tulathromycin concentrations over time in the three matrices. To our knowledge, this is the first validated approach for LC-MS/MS quantification of tulathromycin in seminal plasma and urine.

Florfenicol and Florfenicol Amine Quantification in Bull Serum and Seminal Plasma by a Single Validated UHPLC‐MS/MS Method

“…Other published applications for its quantification in plasma and serum are based on multiple liquid-liquid and/or solid-phase extraction techniques [ 16 , 17 ]. We managed to avoid such expensive and time-consuming approaches, adapting a sample preparation procedure for tulathromycin quantification in plasma, seminal plasma, and urine previously validated by our group [ 20 ]. Moreover, compared to previous studies, the present method reduces sample and organic solvent volumes to just 100 µ L and bypasses the final filtration step.…”

“…All serum and seminal plasma samples were thawed at room temperature (20°C) and prepared using the technique described by Barbarossa et al [ 20 ], with slight modifications. Briefly, 100 µ L of sample and 20 μ L of internal standard working solution (FF-d3 at 2 μ g/mL in acetonitrile) were transferred into a 1.5 mL Eppendorf microtube.…”