High-throughput dispersive liquid/liquid microextraction (DLLME) method for the rapid determination of drugs of abuse, benzodiazepines and other psychotropic medications in blood samples by liquid chromatography–tandem mass spectrometry (LC-MS/MS) and application to forensic cases

The process of dispersive liquid liquid microextraction (DLLME) was successfully applied for the simultaneous extraction and subsequent ultrahigh performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) determination of many different classes of drugs from whole blood samples. Main drugs of abuse (cocaine and metabolites, amphetamines and analogues, LSD, ketamine, opiates including buprenorphine, methadone and fentanyl and analogues), benzodiazepines, Z-compounds and other psychotropic drugs were effectively extracted in a single step and determined with satisfactory sensitivity, accuracy, repeatability and linearity. The matrix effect obtained was very low for all the analytes (maximum of 26% of ion suppression or 28% enhancement at low concentrations), demonstrating the effectiveness of sample purification. The limits of detection (LODs) varied from 0.05 to 2 ng/mL, limits of quantitation (LOQs) from 0.2 to 10 ng/mL. Accuracy and precision were satisfactory: %errors spanned from 0.1 to 15% for drugs of abuse and from 0.4 to 18%, at LOQs, for benzodiazepines and other psychotropic drugs. Interday %CV ranged from 2 to 15 % for drugs of abuse and from 0.2 to 18% (at low concentrations) for other drugs. The method was linear for all the studied analytes, giving regression coefficients (R2) always higher than 0.994. The developed method was successfully applied to the analysis of 50 blood samples from forensic cases, allowing determining the presence of different benzodiazepines in 13 cases, of drugs of abuse in 14 cases, and of other psychotropic drugs in four cases.