Detection and analysis of illegally added sildenafil and its analogues in dietary supplements

To develop a rapid screening method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the identification and quantification of illegally added phosphodiesterase type 5 inhibitors and a tadalafil analog in dietary supplements. Method sensitivity, accuracy, precision, and matrix effects were evaluated. Satisfactory linearity was obtained over 0.8–80.0 μg/mL, with coefficients of determination (r2) of 0.9968–0.9980. The limit of detection and limit of quantification were 0.01 μg/mg and 0.02 μg/mg, respectively. Across three spiking levels (0.8, 8.0, and 80.0 μg/mL), recoveries ranged from 87.3% to 102.4%, with relative standard deviations not exceeding 7.5%. Among 50 commercial dietary supplements, sildenafil, tadalafil, vardenafil, and acetaminotadalafil were detected at concentrations of 0.001–22.5 mg/dose. The method provides high sensitivity, good repeatability, and satisfactory selectivity for preliminary screening and quantification of the validated target analytes in dietary supplements.