A ROBUST SPME-GC-MS METHOD FOR QUANTIFYING CLUB DRUGS IN HUMAN URINE

A solid-phase microextraction-gas chromatographic–mass spectrometric (SPME-GC–MS) method has been developed and validated to measure four common club drugs: γ-hydroxybutyric acid (GHB), methamphetamine (MET), Methylenedioxymethamphetamine (MDMA) and 3,4-Methylenedioxyamphetamine (MDA) in human urine samples. These substances are frequently associated with parties and raves, that’s why they are categorized as 'club drugs.' Deuterium-labeled internal standards were employed for each of the four drugs to enhance quantitation accuracy. The drugs were spiked into urine samples and derivatized with N-methyl-N-trimethylsilyl trifluoroacetamide (MSTFA) to prepare them for GC–MS analysis. The SPME conditions, including extraction time and temperature, as well as desorption time and temperature, were optimized to maximize the peak area for each drug. The final SPME parameters were a 90 °C extraction for 20 minutes, followed by a 1-minute desorption in the GC injector at 225 °C using split-less injection. A 100 µm PDMS fiber from Supelco was used for all SPME procedures. The GC separation was performed on a VF-5ht column (30 m, 0.25 mm i.d., 0.10 µm film thickness) from Varian, using a temperature program ranging from 150 °C to 270 °C at a rate of 10 °C/min. The instrumentation included a ThermoFinnigan Trace GC-Polaris Q, interfaced with a LEAP CombiPal autosampler. Data collection involved using extracted ion chromatograms of specific marker m/z values for each drug from the total ion chromatograms (TIC) in full scan mode. Calibration curves with R² values greater than 0.99 were generated daily, based on the peak area ratios (drug peak area/internal standard peak area) against concentration. The validated method demonstrated intra-day and inter-day precision (% RSD) below 15% and a % error below 15% for four concentrations within the ranges of 0.05–20 µg/mL for MET and 0.10–20 µg/mL for GHB, MDMA, and MDA. This method offers simple sample preparation with acceptable accuracy and precision for the simultaneous quantification of these four drugs of abuse, and it shows no interference from the urine matrix.