Rapid analysis of drugs of abuse and their metabolites in human urine using dilute and shoot liquid chromatography–tandem mass spectrometry

Liquid chromatography-tandem mass spectrometric method for analysis of 113 abuse drugs and their metabolites in human urine was developed and validated. A simple sample clean-up procedure using the “dilute and shoot” approach, followed by reversed phase separation, provided a fast and reliable method for routine analysis. Drugs were separated in a Capcell Pak MG-III C₁₈ column using a gradient elution of 1 mM ammonium formate with 0.1% formic acid in water and acetonitrile. The total time for analysis was 32 min. The multiple reaction monitoring mode using two transitions (e.g., quantifier and qualifier) was optimized for both identification and determination. The calibration curves for each analyte were linear over the concentration ranges of 1–100, 5–100, or 10–100 ng/mL using 400 μL of human urine sample with the coefficient of determination above 0.9921. The coefficient of variation and accuracy for the intra- and inter-assays of the tested drugs at three QC levels were 1.1–14.6 and 86.7–106.8%, respectively. The present method was successfully applied to the analysis of forensic urine samples obtained from 17 drug abusers. This method is useful for the rapid and accurate determination of multiple drug abuse with a small amount of urine in forensic and clinical toxicology.