Analysis of 3,4-methylenedioxymetamphetamine: Whole blood versus dried blood spots

Abstract

Analysis of dried blood spots is an increasingly accepted method in therapeutic drug monitoring, whereas its application by analogy to forensic samples has not been studied in detail. Therefore, we investigated whether determination of 3,4-methylenedioxymethamphetamine (MDMA) and its main metabolite 3,4-methylendioxyamphetamine (MDA) from dried blood spots (DBS) is as reliable as that from whole blood specimens. Analysis was performed by liquid chromatography-tandem mass spectrometry following liquid-liquid extraction of blood and corresponding DBS samples from 20 volunteers participating in a controlled driving experiment under the influence of MDMA. The assay was checked for carryover, ion suppression/enhancement, linearity of response, lower limits of detection (LLOD) and quantitation, extraction efficiency and the within-run and between-run assay imprecision for both whole blood and DBS. The LLODs were 2.0 and 1.6 ng/mL for MDMA in whole blood and DBS, respectively, using a volume of 100 μL. LLODs of MDA were determined to be 0.25 ng/mL in whole blood specimens and 0.12 ng/mL in DBS. Extraction efficiency and imprecision did not differ significantly between the two methods for both MDMA and MDA. The mean concentration ratio of corresponding whole blood and DBS samples, t-test, and the Bland-Altman difference plot were used to test hypothesis of equality. Statistical analyses revealed that methods did not significantly differ for MDMA or MDA. Thus, DBS analysis has potential as a precise and inexpensive alternative to whole blood analysis of MDMA.