UPLC-MS/MS Determination of 5 Kinds of Phosphodiesterase Type 5 Inhibitors Illegally Added in Aphrodisiac Health Products

The grinded sample (0.500 0 g) was ultrasonically dissolved with methanol, and the solution was diluted to 50 mL with methanol and centrifuged at 10 000 r·min^-1 for 10 min. After the supernatant was filtrated with 0.25 μm filter membrane, 5 kinds of illegally added phosphodiesterase type 5 inhibitors (PDE-5) (sildenafil, tadalafil, acetildenafil, vardenafil, pseudo-vardenafil) were separated on a Waters Symmetry Shield RP column (100 mm×2.1 mm, 5 μm), with methanol containing 0.1% (φ) formic acid and 10 mmol·L^-1 ammonium acetate solution containing 0.1% formic acid as the mobile phase for gradient elution. The determination was conducted in positive ESI mode under multiple reaction monitoring mode, with external standard method for quantification. Linear relationships were found between peak areas and mass concentrations of 5 kinds of PDE-5 medicines in definite ranges, with detection limits (3S/N) in the range of 0.25-0.43 mg·kg^-1. Values of recovery obtained by standard addition method were in the range of 97.2%-104%, and RSDs (n=6) ranged from 0.31% to 1.1%. The method was applied to determination of the above PDE-5 medicines in 62 kinds of aphrodisiac health products, and the results showed that 37 kinds of aphrodisiac health products contained illegal added medicines.