The use of nails as an alternative matrix for the long-term detection of previous drug intake: validation of sensitive UHPLC-MS/MS methods for the quantification of 76 substances and comparison of analytical results for drugs in nail and hair samples

This article describes the validation of multi-target methods for the determination of 76 different analytes in hair and nail samples. Segmented hair and nail samples taken from autopsy cases were included in this study. Drugs of abuse, psychotropic drugs, and other drugs were included for the validation of this method. Hair and nail samples were ground using a ball mill and extracted for 18 h. Extracts were measured using a UHPLC-triple quadrupole-mass analyzer. Analytes were separated on a RP 18 column under gradient elution of the mobile phases, water with 0.1 % formic acid and acetonitrile. Whole nail and hair samples from seven autopsy cases were split into segments and analyzed. The entire method was validated according to the German Society of Forensic Toxicology guidelines. In addition, the concentration ratios of selected substances and their metabolites were calculated. Similar concentration ratios in hair and nails were detected for 3,4-methylendioxyamphetamine (MDA)/3,4-methylenedioxy-N-methylamphetamine (MDMA), 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP)/methadone, and bisnortilidine/nortilidine in some of the cases. Reduced 6-monoacetylmorphine (6-MAM) and cocaine concentrations were observed as a result of sample preparation using the ball mill. Previous heroin intake could be assumed from the detection of 6-MAM and morphine in only one nail segment in one case. Nail samples may serve as an alternative matrix for the detection of long-term consumption of a wide range of drugs. Based on our results, drug concentrations in nails are not comparable to those in hair. The main mechanisms for drug incorporation into the nails may be during the formation of the nail plate by the germinal matrix. However, external contamination can also affect the analysis of nail clippings.