MEASUREMENT OF LYSERGIC-ACID DIETHYLAMIDE (LSD) IN HUMAN PLASMA BY GAS-CHROMATOGRAPHY NEGATIVE-ION CHEMICAL IONIZATION MASS-SPECTROMETRY

A previously reported procedure for quantification of LSD in urine was modified to permit measurement of the drug in plasma. After addition of deuterium-labeled LSD, the plasma is extracted and the extract is treated with trifluoroacetylimidazole to convert the LSD to its N-trifluoroacetyl derivative. The derivatized LSD is analyzed by capillary column gas chromatography/negative ion chemical ionization. Plasma fortified with known concentrations of LSD gave linear responses from 0.1 to 3.0 ng/mL with this assay. The method was used to determine pharmacokinetic parameters for LSD after oral administration (1 μg/kg) to a male volunteer. The apparent plasma half-life was determined to be 5.1 h. The peak plasma concentration of 1.9 ng/mL occurred 3 h after administration. © 1990 Oxford University Press.