Ultrasound-assisted liquid-liquid extraction for the determination of methadone in urine samples using gas chromatography-mass spectrometry

Abstract

Background: Methadone abuse and dependence has been reported as a growing concern in some countries. In present study, a rapid, simple, easy and sensitive method for determination of methadone in human urine samples for use in clinical and forensic toxicology and drug screening laboratories was developed and validated. Methods: We determined methadone in urine sampled by gas chromatography/mass spectrometry (GC/MS) and used ultrasound assisted liquid-liquid extraction (UALLE) method for the extraction and preconcentration of methadone before analysis. Results: The limit of detection was 2.1 ng/mL and the limit of quantification 7 ng/mL. Correlation coefficient was 0.9984 for the methadone calibration curve in linear range from 7 to 10,000 ng/mL. The method is accurate and precise. Recovery was in the range of  81.3 % to 97.4 % and enrichment factor was 8.7. The method was successfully applied for determining methadone in clinical and postmortem urine samples. Conclusions: The present method is a rapid, simple, easy and sensitive procedure and can be used in clinical and forensic toxicology laboratories as routine method for qualitative and quantitative analysis of methadone.