MALDI–TOF mass spectrometric determination of four amphetamines in blood

A rapid and sensitive detection method using matrix-assisted laser desorption ionization time-of-flight mass spectrometry was developed for the analysis of amphetamine (A), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethamphetamine (MDMA). In this method, α-cyano-4-hydroxy cinnamic acid was used as the matrix to assist the ionization of amphetamines. The MS spectra of these amphetamines showed protonated molecules [M + H]⁺ and fragment ions with comparable or higher intensities. The quantifications of A and MA were performed using A-d ₇ and MA-d ₅ as the internal standard, respectively, and those of MDA and MDMA were performed using MDMA-d ₅ as the internal standard. The limit of detection and the quantification range using 20 μl of blood were about 10 ng/ml and 30–500 ng/ml for A and MDA, respectively, and about 1 ng/ml and 3–50 ng/ml for MA and MDMA, respectively. In two cases of poisoning in which MA was abused, the levels of A in blood and urine were from 0.050 to 3.24 μg/ml and the levels of MA were from 0.231 to 25.1 μg/ml.