Molecularly imprinted solid-phase extraction for the selective determination of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs in human whole blood by gas chromatography-mass spectrometry

A novel method is described for the extraction of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs, such as 3,4-methylenedioxy-methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine, and 3,4-(methylenedioxyphenyl)-2-butanamine, from human whole blood using molecularly imprinted solid-phase extraction as highly selective sample clean-up technique. Whole blood samples were diluted with 10 mmol/L ammonium acetate (pH 8.6) and applied to a SupelMIP-Amphetamine molecularly imprinted solid-phase extraction cartridge. The cartridge was then washed to eliminate interferences, and the amphetamines of interest were eluted with formic acid/methanol (1:100, v/v). After derivatization with trifluoroacetic anhydride, the analytes were quantified using gas chromatography-mass spectrometry. Recoveries of the seven amphetamines spiked into whole blood were 89.1-102%. The limits of quantification for each compound in 200 μL of whole blood were between 0.25 and 1.0 ng. The maximum intra- and inter-day coefficients of variation were 9.96 and 13.8%, respectively. The results show that methamphetamine, amphetamine, and methylenedioxyphenylalkyl-amine designer drugs can be efficiently extracted from crude biological samples such as whole blood by molecularly imprinted solid-phase extraction with good reproducibility. This extraction method will be useful for the pretreatment of human samples before gas chromatography-mass spectrometry.