Development of surface ionization organic mass spectrometer (SIOMS) for the application to forensic toxicology.

最近，药物滥用问题在日本变得更加重要;越来越多的青少年滥用药物。因此，建立人体体液中滥用药物的灵敏检测方法至关重要。表面电离（英语：Surface ionization，SI）是叔胺化合物在白炽表面上转化正离子的现象;表面电离有机质谱（英语：Surface ionization organic mass spectrometry，SIOMS）是SI作为电离方法的一种应用。SIOMS仪器是四极质谱仪（MS），其被修改为可用于电子撞击（EI）和SI模式。对于SI离子源，将直接进样探针改装为一个带有双灯丝的SI组件，并将其插入EI离子源室的中心。检出限为0.05ng/ml（在质量色谱法中，MC）和0.01 ng/ml（在选择离子监测中，SIM），其与先前的GC/MS方法相比高5 - 200倍（在MC中）和25 - 1000倍（在SIM中）。此外，SI模式中的背景噪声比EI模式小得多。SIOMS对喷他佐辛、MPTP及其类似物、哌替啶和三环类抗抑郁药的敏感性也高得多。喷他佐辛的线性范围为6.25 ~ 100 ng/ml，全血和尿样的检出限均为0.5 ng/ml，其灵敏度比EI-SIM高60倍。因此，SIOMS在检测人体体液中痕量的一些滥用的含有叔氨基基团的药物方面具有高度的可重复性。在未来，我们计划利用串联SIOMS分析化合物的裂解过程。

Recently, the issue of drug abuse has become more important in Japan ; more youngsters use abused drugs. Therefore, it is important to establish sensitive determination methods for abused drugs in human body fluids. Surface ionization (SI) is a phenomenon in which tertiary amino compounds convert positive ions on an incandescent surface ; surface ionization organic mass spectrometry (SIOMS) is an application of SI as an ionization method. The SIOMS instrument was a quadrupole mass spectrometer (MS) , which was modified to be usable in both electron impact (EI) and SI modes. For an SI ion source, the direct inlet probe was remodeled to a SI assembly using a rhenium filament, and it was inserted to the center of an EI ion source chamber.We first tried to detect PCP in human body fluids by SIOMS ; its detection limits were 0.05 ng/ml (in mass chromatography, MC) and 0.01 ng/ml (in the selected ion monitoring, SIM) , which were 5 - 200 (in the MC) and 25 - 1000 (in the SIM) times higher compared to previous GC/MS methods. Moreover, background noises were much smaller in the SI mode than the EI mode. SIOMS also gave much higher sensitivity in pentazocine, MPTP and its analogues, pethidine and tricycle antidepressants. In the case of pentazocine, the calibration curves were linear in the range of 6.25 - 100 ng/ml and the detection limits were 0.5 ng/ml in whole blood and urine sample ; the sensitivity for pentazocine obtained by SIOMS in the SIM mode was about 60 times higher than those obtained by EI-SIM. Consequently, SIOMS is highly recommendable for the detection of trace amounts of some abused drugs containing tertiary amino groups in human body fluids.In the future, we are planning to analyze the process of fragmentation of a compound by tandem SIOMS.