Subject arsenic

The apphcation of many arsenical chemicals are subject to registration and must comply with federal and local government environmental regulations. 

Arsine is used for the preparation of gallium arsenide [1303-00-0] GaAs, (17), and there are numerous patents covering this subject (see Arsenic and ARSENIC alloys). The conversion of a monomeric arsinogaHane to gallium arsenide has also been described (18). GaUium arsenide has important appHcations in the field of optoelectronic and microwave devices (see Lasers Microwave technology Photodetectors). 

Refining. The alloy of bismuth and lead from the separation procedures is treated with molten caustic soda to remove traces of such acidic elements as arsenic and teUutium (4). It is then subjected to the Parkes desilverization process to remove the silver and gold present. This process is also used to remove these elements from lead. 

Metals in the platinum family are recognized for their ability to promote combustion at lowtemperatures. Other catalysts include various oxides of copper, chromium, vanadium, nickel, and cobalt. These catalysts are subject to poisoning, particularly from halogens, halogen and sulfur compounds, zinc, arsenic, lead, mercury, and particulates. It is therefore important that catalyst surfaces be clean and active to ensure optimum performance. 

The production of cobalt is usually subsidiary to that of copper or nickel and the methods employed differ widely, depending on which of these it is associated with. In general the ore is subjected to appropriate roasting treatment so as to remove gangue material as a slag and produce a speiss of mixed metal and oxides. In the case of arsenical ores, AS2O6 is condensed and provides a valuable byproduct. In the case of copper ores, the primary process... 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

If the proplnt is double-base, it has been observed that even the most stable propints bleach methyl violet paper in much shorter periods than one year. Investigations conducted by P.F. Macy at Picatinny Arsenal (Ref 4) showed that diphenylamine-stabilized doublebase proplnts in service storage at about 30°, may be considered of satisfactory stability if they do not cause complete bleaching of 0.1 N methyl violet paper in one month or less. Such proplnts always show satisfactory stability when subjected to the 65.5° Surveillance Test. It was observed at the same time, that double-base proplnts which had deteriorated, but were not yet hazardous, took from 11 to 24 days to bleach methyl violet paper at 30°... 

Arsenically treated wood. Discarded arsenically treated wood or wood products that are hazardous only because they exhibit certain toxic characteristics (e.g., contain harmful concentrations of metal or pesticide constituents), are excluded from the definition of hazardous waste. Once such treated wood is used, it may be disposed of by the user (commercial or residential) without being subject to hazardous waste regulation. This exclusion is based on the fact that the use of such wood products on the land is similar to the common disposal method, which is landfilling. This exclusion applies only to end-users and not to manufacturers. 

Isaeva [181] described a phosphomolybdate method for the determination of phosphate in turbid seawater. Molybdenum titration methods are subject to extensive interferences and are not considered to be reliable when compared with more recently developed methods based on solvent extraction [182-187], such as solvent-extraction spectrophotometric determination of phosphate using molybdate and malachite green [188]. In this method the ion pair formed between malachite green and phosphomolybdate is extracted from the seawater sample with an organic solvent. This extraction achieves a useful 20-fold increase in the concentration of the phosphate in the extract. The detection limit is about 0.1 ig/l, standard deviation 0.05 ng-1 (4.3 xg/l in tap water), and relative standard deviation 1.1%. Most cations and anions found in non-saline waters do not interfere, but arsenic (V) causes large positive errors. 

Berman et al. [735] have shown that if a seawater sample is subjected to 20-fold preconcentration by one of the above techniques, then reliable analysis can be performed by ICP-AES (i.e., concentration of the element in seawater is more than five times the detection limit of the method) for iron, manganese, zinc, copper, and nickel. Lead, cobalt, cadmium, chromium, and arsenic are below the detection limit and cannot be determined reliably by ICP-AES. These latter elements would need at least a hundredfold preconcentration before they could be reliably determined. 

A case report of acute arsine poisoning in which a 27-y-old man was exposed to arsine during chemical manufacturing was reported by Pinto (1976). The subject was exposed to arsine as a result of arsine production via a reaction between a galvanized bucket and an arsenic-containing sulfuric acid solution. The exposure (duration not specified) produced toxic effects characterized by abdominal cramping, thoracic discomfort, and hematuria. Over the next week, the patient s hematocrit declined from 42.5 to 27.1 and hemoglobin dropped from 14.1 to 9.5 g/dL even with medical intervention (blood transfusions and mannitol diuresis). Nine hours after exposure, blood arsenic was 159 g/dL and urinary arsenic was 1862 ug/L. 

Kleinfeld (1980) reported a case of arsine poisoning in a 31-y-old man. The exposure to arsine occurred from a leaking canister thought to be empty. The exposure duration was estimated to be 1-2 min, but no actual or estimated arsine concentrations were available. The victim presented with hematuria. On hospital admission, no intact erythrocytes were present in the urine, hematocrit was 43%, and hemoglobin was 9.8 g/ dL. The hematocrit dropped to as low as 18%, the correction of which required one unit of packed cells. Based upon the exposure history and the subject s note of a "garlicky" odor, the diagnosis was arsine-induced hemolytic anemia. Urinary arsenic was 7.2 mg/L on admission and 0.1 mg/L 4 d later. The patient was subsequently discharged. 

Inorganic arsenicals are oxidized in vivo, biomethylated, and usually excreted rapidly in the urine, but organoarsenicals are usually not subject to similar transformations. 

Numerous criteria for arsenic have been proposed to protect natural resources and human health (Table 28.7). But many authorities recognize that these criteria are not sufficient for adequate or (in some cases) reasonable protection, and that many additional data are required if meaningful standards are to be promulgated (NAS 1977 NRCC 1978 Pershagen and Vahter 1979 USEPA 1980, 1985 Eisler 1994 Abernathy et al. 1997 SEGH1998). Specifically, data are needed on the following subjects ... 

Stations 23 and 24, located in the LSLE, have been subjected to hypoxic conditions since the 1980s. With depletion of oxygen in the bottom waters, the sediment oxygen penetration depth decreased, and Fe oxides, concentrated in the oxic sediment layer, were reductively dissolved and released adsorbed arsenic. Hence, the low oxygen levels during the last 25 years in the bottom waters is reflected in more reducing conditions in the sediment and increases in both dissolved and HA-extractable Fe and As. 

By batch description trials Organo- and inorganically- modified zealot was subjected up to 24 hr in distilled water, tap water and 2% Nalco aqueous solutions in laboratory shaken machine to demonstrate how strongly the examined oxyanions are bound on the modified zeolite. While only slightly chromate desorption in the maximum extent about 20 mg/L was observed, approximately one order higher arsenate desorption was found, corresponding to increased ionic strength in waters. However, in both cases ODA-clinoptilolite exhibited the lowest desorption characteristics. Here, the... 

In all cases where foods subject to the provisions of the Food and Drugs Act of June 30, 1906, are found colored with dyes which contain either arsenic or other poisonous or deleterious ingredient which may render such foods injurious to health, the cases will be reported to the Department of Justice and prosecutions had" (63). 

Theory The official process is a development of the Gutzeit Test wherein all arsenic present is duly converted into arsine gas (AsH3) by subjecting it to reduction with zinc and hydrochloric acid. Further, it depends upon the fact that when arsine comes into contact with dry paper permeated with mercuric (Hg2+) chloride it produces a yellow strain, the intensity of which is directly proportional to the quantity of arsenic present. The various chemical reactions involved may be expressed by the following equations ... 

Apart from exceptional cases, any manufacturer is subject to general regulations induced by the economics of competition, customers rights and requirements, and the legislative arsenal. Figure 7.1 points out some of the main market constraints. 

Experiments with DDT during the war (specifically on soldier test subjects), revealed no apparent short-term harm, however, despite previous animal tests that suggested the chemical was dangerous. The merits of the chemical were compared to the potentially higher danger of existing compounds, especially arsenicals, and it was deemed exceptional and relatively safe. DDT came to replace lead arsenate and other materials (as shown in Figure 4.3 above),i° and Muller won the Nobel Prize for Medicine in 1948. 1... 

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