Simultaneous determination of 25 common pharmaceuticals in whole blood using ultra-performance liquid...

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of 25 common pharmaceuticals in whole blood. The selected pharmaceuticals represent the most frequently detected drugs in our forensic laboratory with basic properties such as analgesics, antidepressants, antihistamines, antihypertensives, antipsychotics and β-blockers. Whole blood samples were extracted with butyl acetate after adjusting pH with 2M NaOH. The target analytes were separated on a 100 × 2.1 mm ACQUITY BEH 1.7 µm C18 column by a formic acid/acetonitrile gradient elution using a Waters ACQUITY Ultra-Performance Liquid Chromatography system. Quantification was performed on a Waters tandem quadrupole ACQUITY TQD using multiple reaction monitoring in positive mode. The analytes were eluted within 11 min. The limit of quantification (LOQ) ranged from 0.002 to 0.01 mg/kg depending on the analyte. A good linear behavior was achieved for all analytes in the range from LOQ to 1.0 or 2.0 mg/kg blood. The absolute recoveries were between 55-87% for all compounds except norfluoxetine (44%). The method showed acceptable precision and accuracy for almost all analytes. Only unstable compounds like levomepromazine, methylphenidate, mirtazapine, norfluoxetine and zuclopenthixol deviated more. The method was successfully applied to more than 200 authentic blood samples within a year from forensic investigations.