UPLC-MS/MS Determination of 22 Forbidden Sedative-Hypnotics in Sleep-Aiding Health Care Products with SPE Column Purification

UPLC-MS/MS was applied to the determination of 22 forbidden sedative-hypnotics in some sleep-aiding health care products. Sample for analysis was prepared by grinding the health care food itself together with its capsula into powder and a portion of 1.000 g was taken and dissolved in methanol with aid of ultrasonic treatment for 15 min. The solution was diluted to 25.0 mL with methanol and centrifuged. An aliquot of 5.00 mL of the supernatant was taken and purified by passing through the Oasis PRiME HLB SPE column. The eluate from the SPE column was collected and mixed with the methanol (2 mL) used in washing the column. The mixed solution was then evaporated to neardryness by N₂-blowing at 40℃. The residue was taken up with 1.00 mL of a mixed solution of 0.005% (volume fraction, same as below) formic acid-methanol with the volume ratio of 1:1, and the solution was filtered through 0.22 μm filtering membrane and the filtrate was used for UPLC separation by passing through Poroshell 120 EC-C₁₈ chromatographic column (50 mm×3.0 mm, 2.7 μm) as stationary phase, and mixture of (A) 5 mmol·L^-1 NH₄OAc solution (containting 0.05% formic acid) and (B) acetonitrile in various ratios were used as mobile phases in gradient elution. In MS/MS determination, ESI and MRM mode were adopted. It was shown that among the standard curves of the 22 forbidden sedative-hypnotics, linearity ranges for 17 sedative-hypnotics were same between 4 μg·L^-1 and 800 μg·L^-1, for one sedative-hypnotic between 40 μg·L^-1 and 8 000 μg·L^-1 and for the remaider 4 sedative-hypnotics between 400 μg·L^-1 and 80 000 μg·L^-1; the detection limits (3S/N) found for these sedative-hypnotics were in the range of 0.02-2 μg·g^-1. Recovery was tested by standard addition method, giving values of recovery in the range of 81.2%-98.9%, and values of RSDs (n=6) in the range of 3.1%-9.7%.