Inorganic arsenic/arsenicals

Apparatus Refer to the figure Special Apparatus for the Determination of Inorganic Arsenic (Arsenic Limit Test, Appendix IIIB). Have all parts available for assembly during the Procedure. 

PHYSICAL PROPERTIES gray, crystalline material soluble inorganic arsenate (arsenic trioxide) predominates under normal conditions MP (817°C 28 atm) BP (613°C) SG (5.727) VP (1 mmHg 372°F)... 

Yeasts, fungi and bacteria are able to convert inorganic arsenic (arsenous and arsenic acids) to organoarsenic species. The pathway can be represented as follows, although not all species have been isolated ... 

The toxicity of arsenic ranges from very low to extremely high depending on the chemical state. Metallic arsenic and arsenious sulfide [1303-33-9] AS2S2, have low toxicity. Arsine is extremely toxic. The toxicity of other organic and inorganic arsenic compounds varies (28). 

Arsine is formed when any inorganic arsenic-bearing material is brought in contact with zinc and sulfuric acid. The arsenides of the electropositive metals are decomposed with the formation of arsine by water or acid. Calcium arsenide [12255-53-7] Ca2As2, treated with water gives a 14% yield of arsine. Better yields (60—90%) are obtained by decomposing a solution of sodium arsenide [12044-25-6] Na As, in Hquid ammonia with ammonium bromide (14,15). Arsine may be accidentally formed by the reaction of arsenic impurities in commercial acids stored in metal tanks, so that a test should be made for... 

Trimethyl arsine [593-88-4] C H As, has been identified as the toxic volatile arsenical, once known as "Gosio gas," produced by the reaction of certain molds that grow on wallpaper paste and react with inorganic arsenic compounds present in the paper. A number of microorganisms can methylate arsenic trioxide and other arsenic-containing compounds to yield trimethylarsine. These microorganisms include Scopulariopsis brevicaulis Candida humicola and Gliocladium roseum (72). 

Inorganic arsenic plus methylated metabolites in End of workweek 35 pg/g As/I B... 

Carcinogenic hazard of wood dusts. Carcinogenicity of crystalline silica Inorganic arsenic compounds... 

From a practical point of view, saturation of elimination has important consequences. If the metabolism becomes saturated, the duration of the action of the compound is prolonged. In such a case, correct timing for collection of biological monitoring samples also becomes difficult to assess. Furthermore, saturation of metabolism may also have qualitative effects. For example, it has been argued (but not yet proved) that arsenic compounds cause cancer at high doses at which methylation of inorganic arsenic becomes saturated. ... 

A mixture of dihydroxyacetone and inorganic arsenate can replace DHAP due to the transient formation of a monoarsenate ester which is recognized by the aldolase as a DHAP mimic21. This approach suffers from the high toxicity of arsenate, especially at the relatively high levels (>0.5 M) needed for efficient conversion, and from problems in product isolation. 

Silver S, LT Phung (2005) Genes and enzymes in bacterial oxidation and reduction of inorganic arsenic. Appl Environ Microbiol 71 599-608. 

As(III), As(V), monomethyl arsonic acid, and dimethylarsenic acid, which gives a quick and reliable estimation of exposure to inorganic arsenic. 

Munoz O, Velez D, Montoro R (1999) Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III) i- As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry. Analyst 124 601-607. 

In 1933 Challenger et al. discovered that trimethylarsine was synthesized from inorganic arsenic compounds by molds (93). Recently, McBride and Wolfe (94), have reported the synthesis of dimethylarsine from arsenate by cell extracts of the methanogenic bacterium M. O. H. Methylcobalamin is the alkylating coenzyme for this synthesis which requires reduction of arsenate to arsenite, methylation of arsenite to methylarsonic acid, reduction and methylation of methylarsonic acid to dimethylarsinic acid, and finally a four electron reduction of dimethylarsinic acid to dimethylarsine (Fig. 13). 

Clearly pollution hazards exist when inorganic arsenic compounds are introduced into an environment where anaerobic bacteria are growing. Arsenic impurities in the phosphate used in detergents and for agricultural practices may pose serious problems because of the continuing synthesis of deadly poisonous methylarsenic compounds. 

Smith E, Naidu R, Alston AM (2002) Chemistry of inorganic arsenic in soils II Effect of phosphorus, sodium, and calcium on arsenic sorption. J Environ Qual 31 557-563... 

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