Rapid enantiomeric analysis of zopiclone in serum by supercritical fluid chromatography–tandem mass spectrometry

Abstract

AbstractZopiclone (ZOP) is a hypnotic drug prescribed to treat insomnia. Due to the chiral nature of ZOP, the psychologically active S‐form and inactive R‐form need to be determined enantiomerically in a forensic drug analysis. In the present study, a supercritical fluid chromatography (SFC) method was designed with a faster analysis ability than that of previously reported techniques. The SFC–tandem mass spectrometry (SFC–MS/MS) method was optimized using a column with a chiral polysaccharide stationary phase (Trefoil CEL2). ZOP was extracted from pooled human serum using solid‐phase extraction (Oasis HLB) and analyzed. The developed SFC–MS/MS method achieved the baseline separation of S‐ZOP and R‐ZOP within 2 min. The fit‐for‐purpose method validation indicated that the optimized solid‐phase extraction achieved near complete recovery and approximately 70% of the matrix effect. Both the retention time and peak area showed sufficient precision. The lower and upper limits of quantification (LOQ) were 5.7 × 10−2 ng/mL and 25 ng/mL for R‐ZOP, and 5.2 × 10−2 ng/mL and 25 ng/mL for S‐ZOP. The calibration line was linear in the range from lower LOQ to upper LOQ. The stability test indicated that ZOP in serum stored in a refrigerator (4°C) degraded and about 55% remained in 31 days. The quick analysis of the SFC–MS/MS method makes it a valid option for the enantiomeric analysis of ZOP.