Pitfalts in the Toxicological Analysis of an Isobutyl Nitrite-Adulterated Coffee Drink

摘要

A forensic investigation was carried out o one poisoning case, where cyanide was first detected in an evidence sample of a canned coffee drink. A more comlete study revealed that it had been adulterated with isobutyl nitrite (IBN) and not cyanide. We examined the detectivity of IBN and related compounds by headspace gas chromatography and capillary electrophoresis. IBN decomposes to isobutyl alcohol(~iBuOH) and nitrite in aqueous solution, and under higher temperature and more acidic conditions, the rate of this reaction becomes more rapid. IBN was also produced by the esterification of ~iBuOH with nitrite below pH 5. Cyaide was produced n a coffee solution by the additon of nitrite below pH 6.An IBN-spikd canned coffee drink solution was stored at 4 deg C ad periodically analyzed for IBN, ~iBuOH, nitrite, nitrate, and cyanide. Since the IBN level decreased rapidly, ~iBuOH was produced in an almost 90% molar yield. Nitrite production reached a maximum of 40% molar recovery on th first day and then gradually disappeared. The nitrate level reached a plateau of approx 60% molar recovery. Cyanide was also detected, and its level at the 14th day was approx 0.26% molar recovery. These findings suggest that, in a coffee drink solution, IBN undergoes hydrolysis to produce ~iBuOH and nitric acid, which is oxidized to nitrate and also produces cyanide throught the nonspecific oxidation of organic compounds under acidic conditions.