Developtment of sensitive and rapid methods for analysis of inorganic toxic substances in human specimens

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1)Ion chromatographic analysis of inorganic toxic substancesOn July 25, 1998, the Wakayama Curry Incident, in which 63 people were injured by arsenic and 4 killed, took place. In the same year, many copycat poisoning incidents using other inorganic toxins followed. Therefore, it was essential for us to be prepared to cope with any type of poison analysis including inorganic ones. We introduced a full system of ion chromatography with an autosuppressor, which could cover the analysis of almost every type of inorganic compounds. As the first study using the above instrument, we established a detailed procedure for analysis of nitrite and nitrate anions in human whole blood. There was a serious problem in the assays of nitrite anion in whole blood, because the retention time of nitrite was very close to that of chloride anion which is abundantly present in whole blood. Before application of a sample to ion chromatography, we succeeded in removing the chloride anion using the combination of cartridges of On Guard II AG and On Grand II H. It was found that most of nitrite was oxidized to nitrate within 3 h in whole blood. The recovery rate for nitrite from whole blood was more than 90 %. The linearity was confirmed in the range of 50-100 μg/ml of whole blood. The detection limit of nitrate was sufficientry low. These data were arranged into a scientific paper, which is now in press in an international journal.2)ESR analysis of inorganic substancesIons of manganese(Mn), molybdenum(Mo) and thiocyanate were tried to be measured by ESR after suitable pretreatments. Mn ion shows paramagnetic property and was thus measurable by ESR only after asking a sample. Mo ion reacted with diethyldithiocarbamate and the complex could be measured by ESR with high sensitivity after reduction by oxalic acid. Thiocyanate could be also measured after complex formation. These results were published in analytical journals.