Liquid chromatography–tandem mass spectrometry determination of LSD, ISO-LSD, and the main metabolite 2-oxo-3-hydroxy-LSD in forensic samples and application in a forensic case

A liquid chromatography-tandem mass spectrometry method was developed to measure LSD, iso-LSD, and the metabolite 2-oxo-3-hydroxy-LSD in forensic samples. The procedure extracts the compounds from whole blood or urine, then uses electrospray ionization and multiple reaction monitoring for detection and quantification. The method is linear over 0.01-50 µg/kg for LSD and iso-LSD, with a quantification limit of 0.01 µg/kg. Applied to a homicide investigation of a 26-year-old man, blood concentrations were 0.27 µg/kg for LSD and 0.44 µg/kg for iso-LSD; the metabolite was detected in urine, confirming LSD use. The case highlights the need to separate isomers before detection because they produce identical fragment ions.

Study at a glance

Abstract

A liquid chromatography mass spectrometric (LC/MS/MS) method has been developed for the determination of LSD, iso-LSD and the metabolite 2-oxo-3-hydroxy-LSD in forensic applications. The procedure involves liquid-liquid extraction of the analytes and LSD-D3 (internal standard) from 1.0 g whole blood or 1.0 ml urine with butyl acetate at pH 9.8. Confirmation and quantification were done by positive electrospray ionisation with a triple quadrupole mass spectrometer operating in multiple reaction monitoring (MRM) mode. Two MRM transitions of each compound were established and identification criteria were set up based on the retention time and the ion ratio. The curves of extracted standards were linear over a working range of 0.01-50 microg/kg for all transitions of LSD and iso-LSD. The limit of quantification was 0.01 microg/kg for LSD and iso-LSD. The method was applied to a case investigation involving a 26-year-old male suspected for having attempted homicide, where blood concentrations of LSD and iso-LSD were determined to 0.27 and 0.44 microg/kg, respectively. 2-Oxo-3-hydroxy-LSD was detected in the urine and confirmed the LSD abuse. The case illustrated the importance of analyte separation before MRM detection of a sample due to identical fragmentation ions of the isomers.