Forensic Toxicology Research and Development Evaluation of New and Novel Direct Sample Introduction, Time of Flight Mass Spectrometry (AccuTOF-DART) Instrument for Postmortem Toxicology Screening

摘要

The National Institute of Justice (NIJ) has sought research and development projects to improve the specificity and sensitivity of analytical tools and technologies used in forensic toxicological analyses. Specifically, NIJ seeks to identify and evaluate tools and technologies that promote faster, more widely applicable, more rugged, less expensive, and less labor-intensive sample analyses. The primary goal of this project was to evaluate a novel direct sample introduction time of flight (TOF) mass spectrometer (JEOL USA, Inc. AccuTOF-DART) for screening postmortem toxicology cases. Early data indicate that this technology has advantages for postmortem toxicology analysesminimal sample preparation (saving labor and improving sample integrity) and a broader ability to detect a range of compounds than is currently available from most technologies. We evaluated the instruments ability to detect 112 different drugs and metabolites of interest in postmortem toxicology from methanolic standard solutions. We found that most drugs could be detected, but that detection limits were too high to see likely therapeutic levels of many drugs. We examined these compounds in urine as well and again found that many drugs were detectable, but that detection limits were not sufficient for concentrations encountered. In blood and tissues, a similar pattern was observed. We encountered interferences from isomers, which cannot be distinguished by exact mass, possibly unresolved compounds affecting mass determination, and other matrix components interfering with ionization (e.g., creatinine). Even with sample preparation, sample handling and sample analysis were very rapid. We also evaluated an autosampler (courtesy of LEAP Technologies) that greatly aided sample handling and contributed to the consistency of results. The JEOL, USA Inc. AccuTOF-DART is a well-constructed instrument that is easily maintained and very robust. The software for the instrument (Mass Center) functions poorly. It is unstable and does not perform in a standard Windows fashion. It is awkward to use and is problematic for forensic handling of data. Overall, the instrument is promising because the very rapid sample analysis and potential broad sensitivity merit efforts to improve sensitivity and the software. The instrument is currently useful for rapid screening of samples for which sensitivity is not a concern, such as drug chemistries. Confirmatory data would be inconsistent, due to issues of isomer identification. Capability for screening in biological samples is currently limited because of sensitivity. Further work to improve the instruments sensitivity and software could result in a very useful instrument for biological samples and other applications.