|SOFT - TIAFT 1998||Scientific Session 4||Thursday October 8, 1998|
|AN IMPROVED SOLID-PHASE EXTRACTION PROCEDURE FOR THE RECOVERY AND QUANTITATION OF AMPHETAMINE AND RELATED COMPOUNDS FROM BLOOD AND HAIR|
|Gail A.A. Cooper1, Thierry D. Mann2, Michael F. Burke2, John S. Oliver1|
1. Department of Forensic Medicine and Science, University of Glasgow, Glasgow, G12 8QQ, Scotland, UK
|Solid-phase extraction (SPE) has become the standard approach to sample preparation for the GC or GC/MS analysis of drugs in biological fluids. While this technology has proven to be applicable to a wide variety of compounds, the determination of amphetamines has been especially challenging because of their volatility. Significant loss of analyte occurs both when the elution solvent is evaporated and under the thermal conditions employed during the derivatisation procedure. A SPE method, which addresses both these limitations, is described for the improved recovery and quantitation of amphetamine (AP), methamphetamine (MA), 3, 4-methylenedioxyamphetamine (MDA), 3, 4-methylenedioxymethamphetamine (MDMA) and 3, 4-methylene-dioxyethylamphetamine (MDEA) in blood and hair.
The initial extraction was achieved using ISOLUTE® CONFIRM HCX mixed-mode SPE columns. The drugs were determined using GC/MS with tri-deuterated amphetamine as the internal standard. The problems with volatility were addressed by simple addition of 100µL of tartaric acid (1mg/mL in ethyl acetate) to each standard and analytical sample prior to evaporating to dryness. All of the amphetamine compounds demonstrated significant increases in recovery.
Data is also presented on the kinetics of the derivatisation of these compounds using pentafluoropropionic anhydride. In contrast to many reports in the literature which call for elevated temperatures (> 40°C) for extended times (> 20 minutes) our data shows that the reaction is complete for all species in less than 2 minutes at room temperature. This represents a significant reduction in the total time of analysis. Recoveries were greater than 87% for all five amphetamines from both blood and hair and were linear over the concentration ranges studied (r2> 0.993).