Application of a high resolution benchtop quadrupole-Orbitrap mass spectrometry for the rapid screening, confirmation and quantification of illegal adulterated phosphodiesterase-5 inhibitors in herbal medicines and dietary supplements.

In this study, the applicability of high resolution quadrupole-Orbitrap (Q-Orbitrap) mass spectrometry for the simultaneous qualitative and quantitative analysis of illegal adulterated phosphodiesterase-5 inhibitors (PDE-5 inhibitors) in herbal medicines and dietary supplements was investigated. The mass spectrometer was operated in full MS scan/dd-MS(2) (data-dependent MS(2)) mode. The use of 70,000 FWHM mass resolution and narrow mass windows (5 ppm) could effectively improve the selectivity of the method, increasing the signal-to-noise ratio for the analytes. The response showed good linear relationship with the analytes' concentrations over wide ranges (e.g., 0.05-10 μg/g for sildenafil) with all the coefficient of determinations (r(2)) >0.9996. The detection limits (LODs) were in the range of 1.0-5.0 ng/g for different analytes. The recoveries ranged from 85.4% to 96.7%. The intra- and inter-day accuracies were in the range of -6.6 to 10.1%, while the intra- and inter-day precision ranged from 0.0039% to 13.2%. Among 68 batches of herbal medicines and 20 batches of dietary supplements (including 83 capsules, 3 pellets and 2 liquid) samples, sildenafil was detected in 8 dietary supplements, while noracetildenafil was detected in only one dietary supplement. The novel Q-Orbitrap mass spectrometry has been proved to be a very promising and powerful tool for routine screening of illegal adulterate in herbal medicines and dietary supplements, ensuring food safety and public health.