Simple and Rapid: An Optimized GC–MS Workflow for Screening Amphetamine in Urine

Abstract

Gas chromatography mass spectrometry is commonly used to analyze biological samples suspected to contain amphetamine. However, samples must often be derivatized, and a balance struck between low-cost (liquid-liquid extraction (LLE)) methods that minimize solvent and sample use (solid-phase microextraction). This study developed and validated a method that does not require sample derivatization and utilizes low-cost LLE while minimizing sample and solvent use. Amphetamine was detected consistently across methanol, artificial urine, and human urine matrices. It had a retention time of 4.1 minutes, with the total runtime being 13 minutes. The limit of detection (LOD) is 0.033 μg/mL which is well below 0.25 μg/mL federal cutoff limit confirming methods utility for forensic analysis. Calibration curves demonstrated excellent R2 > 0.99. The liquid-liquid extraction was with 0.5 mL solvent and 0.5 mL sample. It is the lowest extraction solvent volume using chloroform. Selected Ion Monitoring (SIM) that we targeted were 44, 65, 118 m/z. The dominant quantifier observed under our conditions was 44 m/z, which is a divergence from commonly reported base peaks of m/z 91 or 118. However, it is consistent with our instrument specific fragmentation behavior under the optimized source temperature of 230 °C. The accompanying recovery rate is 84% under basified conditions. By eliminating derivatization and minimizing sample and solvent volume, this method offers a streamlined, reproducible workflow appropriate for routine toxicology laboratory use.