Development and validation of a LC-MS/MS method for the determination of 25 drugs in cerumen and its application to real postmortem samples

Abstract

In the present study a method for the detection of 25 psychoactive substances in cerumen was developed and validated. Method included opiates, cocaine, antidepressants, benzodiazepines, antipsychotics and antiparkinsons. Analysis was performed on a SCIEX Triple Quad 6500+ System after Liquid-Liquid extraction. Methanol with 1% acetic acid was chosen as the extraction solvent. After the addition of the solvent, samples were vortexed, sonicated, centrifuged and directly injected into the LC-MS/MS system. The method was found to be selective and sensitive (LOD: 0.017ng–0.33 ng/mg), with linear regression coefficient ranging from 0.9911 to 0.9999. The intra-assay precision was between 4.34 and 14.6% and inter-assay precision between 5.81 and 17.7%, with accuracy within the acceptable criteria for all analytes. All analytes in cerumen specimens were stable for 48 hours at 4 °C and 72 hours at −20 °C. Additionaly, no significant matrix effect or carryover was observed. Applicability was proven by analyzing cerumen samples from 25 deceased with a history of drug abuse. All analytes were detected in real samples, thus confirming the sensitivity of the developed method. According to our knowledge, it is the first time that a method for the simultaneous detection of 25 psychoactive drugs in cerumen was developed, fully validated and finally applied to 25 postmortem samples.