Journal of Mass Spectrometry
June 1, 2003
Frank T. Peters, Simone Schaëfer, Roland F. Staack et al.
171 citations
A method was developed to screen for and simultaneously quantify classical stimulants (amphetamine, methamphetamine, ethylamphetamine, MDA, MDMA, MDEA, BDB, MBDB) and newer designer drugs (4-methylthioamphetamine, p-methoxyamphetamine, p-methoxymethamphetamine, and several piperazine derivatives) along with two metabolites in human blood plasma. The technique uses gas chromatography/mass spectrometry with selected-ion monitoring after solid-phase extraction and derivatization. The method was linear from 5 to 1000 µg/L for all analytes, with a limit of quantification of 5 µg/L. Accuracy and precision met required limits except for MDBP. The assay was validated and applicable for confirming immunoassay results positive for amphetamines or ecstasy-type designer drugs.
Journal of Analytical Toxicology
November 1, 2003
Frank T. Peters, Nele Samyn, Martin Wahl et al.
65 citations
The pharmacological effects of amphetamine, methamphetamine, MDA, MDMA, and MDEA depend on their mirror-image molecular forms (enantiomers), which differ in how they act in the body. Analysis of plasma from clinical toxicology cases and from drivers suspected of drug impairment showed that concentrations of most enantiomers were lower in routine screening samples than in intoxication or driving-under-the-influence cases. Drivers under the influence had higher levels of both amphetamine enantiomers than intoxicated patients. Differences in the ratio of R to S enantiomers for several drugs between groups suggest these ratios can help distinguish recent from past use. In one MDMA poisoning, the R form cleared more slowly (half-life 6.0 hours) than the S form (4.1 hours), and the ratio of R to S rose over time.
Clinical Chemistry
August 11, 2005
Frank T. Peters, Nele Samyn, C. T. J. Lamers et al.
49 citations
An assay was developed to measure the enantiomers of the designer drugs MDA, MDMA, and MDEA in small plasma volumes (0.2 mL or less). After extraction and derivatization, the enantiomers were separated by gas chromatography and detected by mass spectrometry within 17 minutes. The method was linear for MDA at 1–50 μg/L and for MDMA and MDEA at 5–250 μg/L per enantiomer, with extraction yields of 82.1%–95.3%. Applied to samples from a controlled study after a single 75 mg dose of racemic MDMA, the assay showed that R-(−)-MDMA concentrations significantly exceeded those of S-(+)-MDMA, with ratios always above 1.0 and increasing over time. S-(+)-MDA concentrations exceeded those of R-(−)-MDA, with ratios also increasing but remaining below 1.0.
Clinical Chemistry
March 2, 2007
Frank T. Peters, Nele Samyn, Thomas Kræmer et al.
36 citations
A gas chromatography–mass spectrometry method using negative-ion chemical ionization was developed to separately measure the left- and right-handed forms (enantiomers) of amphetamine, methamphetamine, MDA, MDMA, and MDEA in oral fluid. After adding a buffer and a derivatizing agent, the enantiomers were extracted and analyzed. The method was linear from 5–250 μg/L per enantiomer for MDA and from 25–1250 μg/L per enantiomer for the other drugs. Recoveries and precision were acceptable except for MDEA. When applied to samples from a controlled MDMA study and real driving-under-the-influence cases, the oral fluid concentrations and enantiomer ratios did not reliably predict plasma levels.