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.