Earwax as an alternative specimen for forensic analysis.

In this work, we presented, for the first time, earwax as an alternative forensic specimen for detecting 12 neuropsychotic drugs employing liquid chromatography-tandem mass spectrometry in positive and negative ion modes after straightforward extraction with methanol. The method was validated and standard curves were established by external calibration with correlation coefficients >0.99. All precision, accuracy, matrix effects, extraction recoveries, and carryover were within acceptable limits; limits of quantification were sufficiently low to quantify almost all the samples tested. To confirm the feasibility of the study, earwax specimens were collected from actual patients treated with different combinations of the 12 drugs and analyzed by our method; the 12 drugs could be quantified from the earwax specimens of the users successfully, showing usefulness of earwax specimens, because of its noninvasive sampling and the storage of drug(s) for relatively long time together with its being relatively less contaminated by environmental impurities. This study is pioneering; many detailed studies on earwax as an alternative specimen remain to be explored.