Detection and quantification of benzodiazepines and Z-drugs in human whole blood, plasma, and serum samples as part of a comprehensive multi-analyte LC-MS/MS approach

For the first time, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) multi-analyte approach based on a simple liquid–liquid extraction was developed and validated for fast target screening and quantification of benzodiazepines and Z-drugs in case of driving ability and crime responsibility in the three most important biosamples whole blood, plasma, and serum. Whole blood, plasma, and serum (500 μL each) were extracted twice at pH 7.4 and at pH 10 with ether/ethyl acetate (1:1). Separation, detection, and quantification were performed using LC-MS/MS with electrospray ionization in positive mode. The method was validated with respect to selectivity, ion suppression/enhancement of co-eluting analytes, matrix effects, recovery, process efficiency, accuracy and precision, stabilities, and limits of detection and quantification. For accuracy and precision, full calibration was performed with ranges from subtherapeutic to toxic concentrations. The presented LC-MS/MS approach as part of a universal multi-analyte concept for over 100 drugs was applicable for selective detection as well as accurate and precise quantification in whole blood, plasma, and serum. The approach was selective, sensitive, accurate, and precise for 16 of the 19 tested drugs in whole blood, 18 in plasma, and 17 in serum. Only semiquantitative results could be obtained for zopiclone because of its instability in all tested biosamples.