行政院國家科學委員會專題研究計畫果報告:福馬林固定器官之法醫毒物學研究

Abstract

在法醫鑑定之實際過程中，有時 會遇到死者在生前，甚至死後解剖之 時，並未認為與中毒有關，而依一般 病理解剖之慣例，將器官浸在福馬林 溶液中防腐。因此，在經過一段時間 之後，如懷疑有中毒之可能時，往往 已經無新鮮之器官可供鑑定。 本人過去曾從事由中毒死者之福 馬林固定器官定量除草劑巴拉刮 (paraquat)。本研究乃是進一步發展另 外一種台灣常發生之中毒農藥巴拉松 (parathion)， 其器官經福馬林固定之 後，以硫酸加熱分解，經以Toluene 與Ethyl Ether 之混合溶劑萃取後，再 以2N NH4OH 萃取pNP。經呈色反應 之後， 以分光光譜儀掃描550-750 nm。並以一次微分(1st. Derivative)之 光譜。以574 nm 與672 nm 波長吸 光值之差以計算pNP 之濃度。 結果顯示0.2 至5.0 μ g/mL pNP 之標準曲線，其線性相當良好( r2 = 0.9999 ) 。檢出極限為0.03 μ g/mL。 - 1 - 將pNP 加入水中及老鼠之肝 臟， 經利用所發展之方法定量之結 果，其濃度為0.2-5.0μg/mL 時其回收率 為86-91%，其平均值為89%，相當理 想。 由懷疑為巴拉松中毒，且其器官經 福馬林固定之死者，經利用此法定量 之結果，其腎臟高達67.4μg/mL，肝臟 為2.2 μg/mL，皆可測出pNP。因此， 本新方法證明可以應用於法醫毒物學之 鑑定。

Parathion, o,o-diethyl-o-p-nitrophenyl phosphrothionate, is a volatile organophosphorous pesticide. The fatal intoxication by parathion is mostly the result of oral ingestion for the purpose of suicide. On the other hand, accidental inhalation and topical exposures to parathion during the formulation or the spray of this pesticide by worker or farmer are the common routes of entry for systemic effects. It has been known that parathion undergoes P450-dependent oxidative desulfuration, metabolizing to paraoxon which potentially inhibited acetylcholinesterase and resulted in muscarinic and nicotinic symptoms. The main metabolite of parathion was p-nitrophenyl-glucuronide (pNP) making up 85% of the urinary excretion, about 6% was excreted as pnitrophenyl- sulfate and only 1% as free pNP Although the severity of intoxication and the time of survival correlated well with the dose of parathion, the potency of paraoxon to inhibit AChE fails to predict the acute toxicity class.. A novel method for the determination of pNP in formalin-fexed tissures of suspected patient with parathion intoxication has been developed. The method is based on the hydrolysis of conjugated pNP with concentrated sulfuric acid. P-nitrophenol was extracted with toluene-ether mixtures, then back extracted into 2N NH4OH. After reacting with phenol and reducing with TiCl3, the indophenol blue was measured by 1storder derivative spectrophotometry. The results showed that the linearity of the standard curves measured 1st.-order derivative spectrophotometry were excellant in the range of 0.2-5.0 μ g/mL (r2 = 0.9999 ). Recoveries of 89% were obtained from the spiked formalin-fixed rat liver by 1st-order spectrophotometry. On the other hand, the digestion efficiencies of formalin-fixed tissures with sulfuric acid were better than those of microwave. The assay, which has a limit of detection of 0.03 μ g/mL, is accurate, reproducible and much more sensitive than traditional spectrophotometry. It has been applied to determine pNP in the formalin-fixed tissues of victim with suspected parathion poisoning. It was found that the concentrations of pNP in formalin-fixed liver and kidney were 2.2 and 67.4 μg/mL, respectively. It revealed that this proposed method could be used for the purposes of forensic toxicology.