Analysis of amphetamine, methamphetamine, methylenedioxyamphetamine and methylenedioxymethamphetamine in whole blood using in-matrix ethyl chloroformate derivatization and automated headspace solid-phase microextraction followed by GC-MS

The in-matrix alkyl chloroformate derivatization method for amphetamine, methamphetamine, methylenedioxyamphetamine (MDA), and methylene-dioxymethamphetamine (MDMA) was adapted for use with the whole blood matrix. This derivatization method was followed by automated headspace (HS)-solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) analysis. The sensitivity of this method, expressed as limit of detection, was approximately 10 ng/ml for these analytes tested in the blood matrix, which was sufficient to detect toxic concentrations of amphetamines in blood. The limit of quantitation for target analytes ranged from 0.05 to 0.2 μg/ml. The intraday precision and accuracy studies generally showed satisfactory results for all target compounds except MDA, in which a larger variation was observed. The in-matrix ethyl chloroformate derivatization of amphetamine, methamphetamine, MDA, and MDMA for HS-SPME was tested in other matrices such as stomach fluid, bile, thoracic cavity fluid, vitreous humor, brain, liver, spleen, and skeletal muscle. As a result, stomach fluid, thoracic cavity fluid, and vitreous humor showed SPME efficiencies higher than that of whole blood; however, this method was not suitable for solid tissue matrices under the present conditions.