[Development of High-resolution Methods for the Analysis of Drug Distribution in Biological Tissue Samples and Their Applications].

The abuse of drugs has become a serious social problem worldwide. Amphetamine-type stimulants such as methamphetamine are recreationally abused and can cause toxic effects in the body. Unfortunately, death from drug poisoning can occur due to careless intake. In postmortem examinations, the distribution of drugs in an entire organ gives valuable information for evaluating their toxicity. We developed methods to measure the distribution of drugs in organs using LC/MS and matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). The complementary use of the two methods provides more detailed information on the distribution and concentration of drugs in organs because the accurate quantification in LC/MS and small spatial resolution in MALDI-IMS are combined. On the other hand, it is important to elucidate the drug intake history of suspects and victims in drug-facilitated crimes (DFCs). Hair and nail samples are often used to confirm chronic drug intake because ingested drugs can stably remain in these specimens over several months. However, it is impossible to determine the day of drug ingestion in conventional segmental analysis of bulk samples. Therefore, we developed methods to cut hair strands at 0.4-mm intervals and nails at 0.2-mm intervals, which correspond to their respective growth rates over 1-2 d, to analyze the drugs in each segment efficiently using LC/MS. The microsegmental hair analysis method is applied to estimate the day of drug ingestion in DFC investigations. These methods could be applied to measure the distribution of compounds in various solid samples.