Arsenic, in organic compounds

Tuckerman and collaborators state that chloric acid is to be preferred to the more widely used sulphuric acid or sulphuric-nitric acid digestions or alkaline fusions recommended for the determination of arsenic in organic compounds. Excess chloric acid is easily removed by boiling to leave a perchloric acid solution of inorganic As(V). Rapid micro and semi-micro methods for the determination of arsenic based on chloric acid digestion are described. 

The determination of carbon and arsenic in organic compounds using magnesium fusion and the elemental analysis of organoarsines and organobromoarsines have been... 

G. Arsenic in Organic Compounds Test by ignition with lime (conversion to arsenate)... 

In non-saline sediments aliphatic and polyaromatic hydrocarbons, phthalate esters carboxylic acids, uronic acid aldoses chloroaliphatics haloaromatics chlorophenols chloroanisoles polychlorobiphenyls polychlorodibenzo-p-dioxins poychlorodibenzofurans various organosulphur compounds, chlorinated insecticides, organophosphorus insecticides mixtures of organic compounds triazine herbicides arsenic and organic compounds of mercury and tin. 

Other elements which occur in organic compounds, such as phosphorus, arsenic, other non-metals, and metals in organic combination, are detected by destroying the organic material by oxidation (with nitric acid in a sealed tube or by fusion with potassium nitrate or sodium peroxide) and then applying the usual tests. 

From the determination of the molecular refractions of a large number of organic compounds containing tervalent arsenic, the atomic refraction of arsenic in each compound has been calculated,10 the values obtained varying from 9-2 to 14-39. Hydrogen, chlorine and alkyl groups in an arsine exert about the same influence on the atomic refraction of arsenic, but replacement of any of these by aryl groups causes an increase in the atomic refraction. The opposite effect results from substitution by a cyanide, oxalate or alkoxyl radical. 

After cooling, the flask is shaken thoroughly and disassembled, and the inner surfaces are cai-efully rinsed. The analysis is then performed on the resulting solution. This procedure has been applied to the determination of halogens, sulfur, phosphorus, fluorine, arsenic, boron, carbon, and various metals in organic compounds. 

Once inside the cell, arsenate ions can be reduced to arsenite via membrane-bound or cytoplasmic enzymes. The former are linked to cellular energy conservation and are described in detail later in this chapter and in Chapter 12 the latter are characteristic of As-resistant microbes, do not conserve energy, and have been described in Chapter 10. Before detailing the bioinorganic chemistry of arsenic by micro-organisms, however, we will briefly discuss the incorporation of arsenic into organic compounds. For more details on this subject, we refer the reader to comprehensive reviews by Phillips (6) and Reimer (7). 

P. F. Wyatt "Diethylammonium Diethyldithiocarbamate for the Separation and Determination of Small Amounts of Metals. II. The Isolation and Determination of Arsenic, Antimony, and Tin in Organic Compounds" Analyst 80, 368-79 (1955). 

Lead oxide is used in producing fine "crystal glass" and "flint glass" of a high index of refraction for achromatic lenses. The nitrate and the acetate are soluble salts. Lead salts such as lead arsenate have been used as insecticides, but their use in recent years has been practically eliminated in favor of less harmful organic compounds. 

Also formed by the direct combination of the elements is a red soHd compound, arsenic diiodide [13453-17-3] AS2I4 or ASI2, which melts at 130°C and dissolves in organic solvents. Treatment of this compound with water causes disproportionation. 

Heteropolyacids (HPA) are the unique class of inorganic complexes. They are widely used in different areas of science in biochemistry for the precipitation of albumens and alkaloids, in medicine as anticarcinogenic agents, in industry as catalysts. HPA are well known analytical reagents for determination of phosphoms, silica and arsenic, nitrogen-containing organic compounds, oxidants and reductants in solution etc. 

In catalytic incineration, there are limitations concerning the effluent streams to be treated. Waste gases with organic compound contents higher than 20% of LET (lower explosion limit) are not suitable, as the heat content released in the oxidation process increases the catalyst bed temperature above 650 °C. This is normally the maximum permissible temperature to which a catalyst bed can be continuously exposed. The problem is solved by dilution-, this method increases the furnace volume and hence the investment and operation costs. Concentrations between 2% and 20% of LET are optimal, The catalytic incinerator is not recommended without prefiltration for waste gases containing particulate matter or liquids which cannot be vaporized. The waste gas must not contain catalyst poisons, such as phosphorus, arsenic, antimony, lead, zinc, mercury, tin, sulfur, or iron oxide.(see Table 1.3.111... 

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