tailieunhanh - Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 13)

Introduction: Methanol (methyl alcohol) poisoning accidents take place most frequently by drinking it in mistake for ethanol. Methanol poisoning is not due to the effect of methanol itself, but due to toxicity of its metabolites. Methanol is rapidly absorbed into human body through the airway mucous membranes, digestive tract mucous membranes or the skin; it is metabolized into formaldehyde (formalin, HCHO) and then formic acid (HCOOH) by the actions of alcohol dehydrogenase and aldehyde dehydrogenase, respectively. Formic acid inhibits cytochrome oxidase in the optic nerves, and causes visual disturbances followed by the loss of eyesight. The accumulation of formic acid. | Methanol and formic acid by Xiao-Pen Lee and Keizo Sato Introduction Methanol methyl alcohol poisoning accidents take place most frequently by drinking it in mistake for ethanol. Methanol poisoning is not due to the effect of methanol itself but due to toxicity of its metabolites. Methanol is rapidly absorbed into human body through the airway mucous membranes digestive tract mucous membranes or the skin it is metabolized into formaldehyde formalin HCHO and then formic acid HCOOH by the actions of alcohol dehydrogenase and aldehyde dehydrogenase respectively. Formic acid inhibits cytochrome oxidase in the optic nerves and causes visual disturbances followed by the loss of eyesight. The accumulation of formic acid in the body provokes severe acidosis which is characteristic for methanol poisoning. The metabolic oxidation velocity for methanol is about 5-10 times slower than that for ethanol. This is the reason why the poisoning symptoms do not appear soon after its ingestion but appear after a while. Formic acid can be detected from urine for about one week after methanol ingestion. It is possible to diagnose methanol poisoning by detecting methanol and or formic acid from blood and urine specimens. For analysis of methanol and formic acid GC methods with packed columns were employed 1-5 . In this chapter GC methods for analysis of them in blood and urine using a wide-bore capillary column and using solid-phase microextraction SPME 6-9 are presented. Analysis of methanol Reagents and their preparation in common with both wide-bore capillary GC and headspace SPME-GC Methanol standard solution a mL volume of methanol of special grade is dissolved in 100 mL distilled water to prepare 1 mg mL solution. Internal standard IS solution a mL volume of acetonitrile of special grade is dissolved in 100 mL distilled water to prepare 1 mg mL solution. Conditions for wide-bore capillary GC Column an Rtx-BAC2 wide-bore capillary column 30 m x mm . film .