tailieunhanh - Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 11)

Introduction: Hydrogen sulfide (H2S) is a colorless gas with the smell of putrid eggs; it can exist in both nonionic and ionic forms in aqueous solution. The ratio of the nonionic form to the total ionized one is influenced by concentration of hydrogen ion in the solution. Under acidic conditions, H2S does not ionized and evaporated from water; under alkaline conditions it is easily ionized and retained in the solution. As toxic effects of H2S, it (at higher than 700 ppm) acts on the central nervous system causing generalized poisoning, and also shows localized inflammatory effects on the wet mucous. | Hydrogen sulfide and its metabolite By Shigetoshi Kage Introduction Hydrogen sulfide H2S is a colorless gas with the smell of putrid eggs it can exist in both nonionic and ionic forms in aqueous solution. The ratio of the nonionic form to the total ionized one is influenced by concentration of hydrogen ion in the solution. Under acidic conditions H2S does not ionized and evaporated from water under alkaline conditions it is easily ionized and retained in the solution. As toxic effects of H2S it at higher than 700 ppm acts on the central nervous system causing generalized poisoning and also shows localized inflammatory effects on the wet mucous membranes of the eye and respiratory organs. H2S poisoning together with oxygen deficiency is most frequent in industries the former is also occurring at sewers sewage treatment institutions petroleum refineries sodium sulfide factories and zones of volcanos and spas. The poisoning can also occur by ingesting a pesticide of the lime-sulfur mixture or bath salts including sulfur. It is necessary to analyze H2S in blood of a poisoned patient to verify its poisoning. The analytical methods for H2S can be classified into two groups methods for detecting nonionic H2S under acidic conditions and those for detecting an ionized from of H2S under alkaline conditions. In this chapter a method of GC with a flame photometric detector FPD for analysis of the nonionic H2S and a method of GC MS for the ionized form with derivatization are presented. H2S is easily oxidized to thiosulfate and sulfate in a human body 1-3 . The levels of sulfate in blood and urine of non-poisoned subjects are relatively high making sulfate difficult to be used as an indicator of H2S poisoning. However thiosulfate can be used as the indicator of the poisoning 4-9 because its endogenous levels in human blood and urine are usually lowa. Therefore a method for detecting this metabolite is also presented. GC analysis of Hydrogen sulfide H2S in blood See 10 .