Ultrasound-Assisted Liquid-Liquid Extraction for Analyzing Methadone in Urine Samples by Gas Chromatography-Mass Spectrometry

Methadone abuse and dependence are a growing concern in some countries. The present study developed and validated a rapid, simple, easy, and sensitive method for analyzing methadone in urine specimens. This approach was intended for use in clinical and forensic toxicology and drug screening laboratories.

We determined methadone in urine samples by Gas Chromatography / Mass Spectrometry (GC / MS). Besides, we used Ultrasound-Assisted Liquid-Liquid Extraction (UALLE) method for the extraction and preconcentration of methadone before analysis.

The detection limit was 2.1 ng/mL and the limit of quantification equaled 7 ng/mL. The methadone calibration curve was linear and ranged from 7 to 10000 ng/mL, and the correlation coefficient was calculated as 0.9984. The tested method was accurate and precise. Recovery fell in the range of 81.3% to 97.4% and the enrichment factor was measured as 8.7. The method was successfully used for determining methadone in real clinical and postmortem urine samples.

The presented method was a rapid, easy, simple, and sensitive procedure; thus, it could be applied in clinical and forensic toxicology laboratories as a routine approach for analyzing methadone.