OBJECTIVE  To establish a QuEChERS-high performance liquid chromatography-tandem mass spectrometry with isotope internal standards method for the simultaneous determination of vitamins D and K in 5 different matrixes of cosmetics (water aqua, lotion, cream, gel and powder).

METHODS  Samples were ultrasonically extracted by acetonitrile, and then purified by optimized QuEChERS method (150 mg magnesium sulfate, 50 mg PSA). The separation was performed on an ACQUITY UPLC BEH C₁₈(2.1 mm×50 mm, 1.7 µm) column using methanol(containing 0.05% formic acid and 5 mmol·L⁻¹ ammonium formate) as the mobile phase. The determination was performed by MS/MS in electrospray ionization positive mode(ESI+) and multiple reaction monitoring mode, and isotope internal standard method was used for quantitative analysis.

RESULTS  The linear relationship of vitamins D(D₂, D₃) and K(K₁, K₂) was good in the concentration range of 5−500 ng·mL⁻¹, and the correlation coefficients (r) were all larger than 0.995. The limits of detection and limits of quantification were 0.01 μg·g⁻¹ and 0.03 μg·g⁻¹, respectively. At 3 different concentrations, the recoveries of water aqua, lotion, cream, gel and powder samples were 94.0%−110.1%, 89.4%−111.5%, 90.1%−106.8%, 93.8%−109.7% and 89.9%−106.2%, respectively. The RSD were all less than 8.0%.

CONCLUSION  This method is simple, sensitive and accurate, which is suitable for the determination of the vitamins D and K in cosmetics.