Rapid and precise identification of toxic substances is necessary for urgent diagnosis and treatment of
poisoning cases and for establishing the cause of death in postmortem examinations. However, identification of compounds in
biological samples using gas chromatography and liquid chromatography coupled with mass spectrometry entails time-consuming and labor-intensive sample preparations. In this study, we examined a simple preparation and highly sensitive analysis of drugs in
biological samples such as urine, plasma, and organs using thin-layer chromatography coupled with matrix-assisted
laser desorption/ionization mass spectrometry (TLC/MALDI/MS). When the urine containing 3,4-methylenedioxymethamphetamine (
MDMA) without sample dilution was spotted on a thin-layer chromatography (TLC) plate and was analyzed by TLC/MALDI/MS, the detection limit of the
MDMA spot was 0.05 ng/spot. The value was the same as that in aqueous
solution spotted on a
stainless steel plate. All the 11 psychotropic compounds tested (
MDMA, 4-hydroxy-3-methoxymethamphetamine,
3,4-methylenedioxyamphetamine,
methamphetamine,
p-hydroxymethamphetamine,
amphetamine,
ketamine,
caffeine,
chlorpromazine,
triazolam, and
morphine) on a TLC plate were detected at levels of 0.05-5 ng, and the type (layer thickness and fluorescence) of TLC plate did not affect detection sensitivity. In addition, when rat liver homogenate obtained after
MDMA administration (10 mg/kg) was spotted on a TLC plate,
MDMA and its main metabolites were identified using TLC/MALDI/MS, and the spots on a TLC plate were visualized by MALDI/imaging MS. The total analytical time from
spotting of intact
biological samples to the output of analytical results was within 30 min. TLC/MALDI/MS enabled rapid, simple, and highly sensitive analysis of drugs from intact
biological samples and
crude extracts. Accordingly, this method could be applied to rapid
drug screening and precise identification of toxic substances in
poisoning cases and postmortem examinations.