Quantitation of 25-hydroxyvitamin D2 and D3 in serum and plasma by LCMS/MS

Objective: We developed and validated an analytical method for quantifying 25-hydroxyvitamin D2 (25OHD2) and 25-hydroxyvitamin D3 (25OHD3) in serum and plasma. Methods: Samples, pretreated with zinc sulfate and methanol, were extracted with hexane. Separation was achieved via UHPLC and 25OHD quantification was accomplished by a triple quadrupole mass spectrometer. Results: Imprecision was 3.6–15.1%CV and bias 88.0–126.0%. Extraction efficiency was 76.5–110.5%, whereas the matrix effect ranged from −46.7 to −32.0%. The method was applied to authentic specimens. The results showed no significant difference between serum and plasma; strong correlation with paired values from an external laboratory; and analyte stability for 15...