Comparison of the immunoassay method with the commercial and in-house LC-MS/MS methods for substance abuse in urine

Abstract Objectives The aim of this study was to compare the analytical performance of the KIMS (kinetic interaction of microparticles in solution) immunochemical method with a validated in-house and a commercial LC-MS/MS method. Methods The urine samples of the 100 subjects were included in the present study. The urine samples were analysed with Roche DAT immunochemical method based on KIMS method. In-house LC-MS/MS method was validated for 58 parameters according to the CLSI C62-A recommendations with the following parameters: matrix effect, lower limit of quantification (LLOQ), linearity, intra-day and inter-day precision and accuracy. Eureka Lab Division Drugs of Abuse kit was used as the commercial LC-MS/MS method. Results The immunochemical method had a satisfactory performance with specificity, sensitivity and accuracy values above 80 % and met the DRUID recommendation except benzodiazepines. The sensitivity and specificity of the immunochemical method were between 97–100 % and 84–100 %, respectively (except for benzodiazepines). The bias obtained for THC-COOH, morphine and codeine parameters were −17.5, 24.6 and 43.6 between two LC-MS/MS methods. The commercial method had a tendency to have a negative bias except for cannabinoids. Conclusions The analytical performance of the KIMS-based urine immunochemical method was found to be satisfactory for the intended use, except for benzodiazepines. The validated urine in-house LC-MS/MS method was found to be a good alternative for confirmation of substance abuse.