HPLC QTRAP-MS/MS Determination of Zolpidem and Zaleplon in Blood

Blood sample (0.50 mL) was mixed with 0.3 mL of ammonium acetate buffer solution (pH 10), and the mixture was purified on the supported liquid extraction column and 8 mL of dichloromethane was used as eluent. The treated eluate was separated by HPLC using Kinetex C₁₈ column as stationary phase and mixtures of acetonitrile and 0.1% (φ) formic acid solution containing 5 mmol·L^-1 ammonium acetate, mixed in various ratios, as mobile phase in gradient elution. ESI⁺ and MRM were adopted in MS. Linear relationships between values of peak area and mass concentration were found in the ranges of 0.20-10.00 μg·L^-1 for zolpidem and 1.00-50.00 μg·L^-1 for zaleplon, with detection limits (3S/N) of 0.02, 0.10 μg·L^-1, respectively. Test for recovery was made by standard addition method, giving results in the range of 85.0%-103%, with RSDs (n=6) ranged from 3.5% to 8.5%.