Detection of meperidine and its metabolites in the hair of meperidine addicts

The presence of meperidine and its metabolites in the hair of meperidine addicts was investigated using GC–MS (EI, PCI). Meperidine and its three metabolites – normeperidine, N-methoxy meperidine and acetyl normeperidine, were found in hair samples from addicted subjects. Methods for the simultaneous determination of meperidine and its metabolites by GC–MS-SIM were also established for human hair samples. After the addition of d₄-meperidine as an internal standard, hair samples weighing 5 mg were incubated in 0.1 M HCl at 45°C overnight, and the resulting digests were extracted with ether. The recoveries were greater than 80%, with coefficients of variation (CVs) between 4.48 and 8.31%. The calibration curves for meperidine and normeperidine in hair were linear over a concentration range of 1 to 500 ng per mg of hair, with correlation coefficients of r=0.9990 and r=0.9992, respectively. Values less than 0.25 ng/mg of hair were cut off. Hair samples obtained from 60 drug addicts were analyzed using this method, and the content of meperidine and normeperidine was determined to be 103±130 and 117±143 ng/mg, respectively. Sectional analysis revealed that meperidine was present and stable in hair for at least 20 months, but normeperidine content at the level of the hair root was higher compared to the tip of the hair shaft. The results also revealed that there was a correlation between the subject’s drug abuse history and the distribution of drug along the hair shaft, and between the doses of meperidine and drug content presented in hair.