Simultaneous determination of trantinterol and its metabolites in rat urine and feces by liquid chromatography–tandem mass spectrometry

A highly selective and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of trantinterol (SPFF) and its major metabolites for the first time. The analytes were extracted from rat urine and feces samples by liquid–liquid extraction (LLE) and determined in multiple reaction monitoring (MRM) mode with clenbuterol as the internal standard. Chromatographic separation was achieved on a Venusil ASB C8 column (2.1 mm × 100 mm, 3 μm), with the mobile phase consisted of methanol–0.2% formic acid (30:70, v/v) at the flow rate of 0.2 mL/min. Each sample was chromatographed within 5 min. This method has a lower limit of quantification (LLOQ) of 0.450, 1.05, 1.35, 0.904 and 1.36 ng/mL for trantinterol (SPFF), arylhydroxylamine trantinterol (N-OH-SPFF), tert-butyl hydroxylated trantinterol (Tert-OH-SPFF), 1-carbonyl trantinterol (SPFF-COOH) and 3-methyl sulfone-dechloro-trantinterol (SPFF-SO2CH3) in rat urine, and 0.450, 1.35 and 0.904 ng/mL for SPFF, Tert-OH-SPFF and SPFF-COOH in rat feces, respectively. The linear correlation coefficients were greater than 0.990. The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was −9.9% to 11% at three quality control levels. The method has been successfully applied to the excretion study following an oral administration of 1 mg/kg trantinterol to rats.