Development of an ultra-high-performance liquid chromatography coupled to high-resolution quadrupole-Orbitrap mass spectrometry method for the rapid detection and confirmation of illegal adulterated sedative-hypnotics in dietary supplements

A novel method using ultra-high performance liquid chromatography coupled to hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap) was developed and validated for the simultaneous screening, identification and quantification of sedative-hypnotics in dietary supplements. Chromatographic conditions were optimised and a full data-dependent MS2 scan (MS/dd-MS2) in positive and negative ion mode was used. A single injection was sufficient to perform the simultaneous screening and identification/quantification of samples. The response showed a good linear relationship with analyte concentrations over wide ranges (e.g., 1.0–1000 ng g–1 for diazepam) with all the determination coefficients (r2) > 0.9985. The method was validated, obtaining accuracy (intra- and inter-day) in the range of 94.5–105.3% and precision (intra- and inter-day) in the range of 0.4–8.9%, respectively. The detection limits (LODs) were in the range of 0.3–1.0 ng g–1 for different analytes. Recoveries were performed and ranged from 74.1% to 90.2%, while all matrix effects were over the range of 85.4–93.6%. Finally, this method was used to detect sedative-hypnotics in commercial dietary supplements. Of a total of 45 batches of dietary supplements, only three batches were found to be positive samples with concentrations of diazepam, clonazepam and alprazolam at high levels (≥ 8.22 mg g–1).