Antimony method

Once we have a supply of Animated Mercury from one of the above methods, or from the Star Regulus of Antimony method, the next step is to form the so-called Re bis wherein the opposites are united. 

A complete set of trihalides for arsenic, antimony and bismuth can be prepared by the direct combination of the elements although other methods of preparation can sometimes be used. The vigour of the direct combination reaction for a given metal decreases from fluorine to iodine (except in the case of bismuth which does not react readily with fluorine) and for a given halogen, from arsenic to bismuth. 

The standard synthesis method features side-chain chlorination of a methylpyridine (picoline), followed by exchange-fluoriaation with hydrogen fluoride or antimony fluorides (432,433). The fluoriaation of pyridinecarboxyHc acids by sulfur tetrafluoride (434) or molybdenum hexafluoride (435) is of limited value for high volume production operations due to high cost of fluorinating agent. 

Two methods are used to measure pH electrometric and chemical indicator (1 7). The most common is electrometric and uses the commercial pH meter with a glass electrode. This procedure is based on the measurement of the difference between the pH of an unknown or test solution and that of a standard solution. The instmment measures the emf developed between the glass electrode and a reference electrode of constant potential. The difference in emf when the electrodes are removed from the standard solution and placed in the test solution is converted to a difference in pH. Electrodes based on metal—metal oxides, eg, antimony—antimony oxide (see Antimony AND ANTIMONY ALLOYS Antimony COMPOUNDS), have also found use as pH sensors (8), especially for industrial appHcations where superior mechanical stabiUty is needed (see Sensors). However, because of the presence of the metallic element, these electrodes suffer from interferences by oxidation—reduction systems in the test solution. 

A rapid method to determine the calcium content of lead alloys is a Hquid-metal titration using lead—antimony (1%) (9). The end point is indicated by a gray oxide film pattern on the surface of a sohdifted sample of the metal when observed at a 45° angle to a light source. The basis for the titration is the reaction between calcium and antimony. The percentage of calcium in the sample can be calculated from the amount of antimony used. If additional calcium is needed in the alloy, the melt is sweetened with a lead—calcium (1 wt %) master alloy. 

The standard chemical and biological methods of analysis are those accepted by the JnitedStates Pharmacopeia XXIII as well as the ones accepted by the AO AC in 1995 (81—84). The USP method involves saponification of the sample (dry concentrate, premix, powder, capsule, tablet, or aqueous suspension) with aqueous alcohoHc KOH solvent extraction solvent removal chromatographic separation of vitamin D from extraneous ingredients and colormetric deterrnination with antimony trichloride and comparison with a solution of USP cholecalciferol reference standard. 

Analysis of zinc solutions at the purification stage before electrolysis is critical and several metals present in low concentrations are monitored carefully. Methods vary from plant to plant but are highly specific and usually capable of detecting 0.1 ppm or less. Colorimetric process-control methods are used for cobalt, antimony, and germanium, turbidimetric methods for cadmium and copper. Alternatively, cadmium, cobalt, and copper are determined polarographicaHy, arsenic and antimony by a modified Gutzeit test, and nickel with a dimethylglyoxime spot test. 

The antimony content of commercial ores ranges from 5 to 60%, and deterrnines the method of treatment, either pyrometaHurgical or hydrometaHurgical. 

High purity stibiae is used as an -type, gas-phase dopant for Si in semiconductors (14). Low temperature distillation of stibiae at <53.3 kPa (400 torr) yields a product that on decomposition gives metallic antimony having less than 8 x lO " % impurity (18). A method for determining quantities of stibiae in the neighborhood of 0.1 mg/m in air has been reported (19). 

Common methods of preparation include direct combination of metallic antimony with air or oxygen, roasting of antimony trisulfide, and alkaline hydrolysis of an antimony ttihafide and subsequent dehydration of the resulting hydrous oxide when heated too vigorously in air, some of the Sb(III) is converted to Sb(V). 

Antimony pentafluoride may be prepared by fluorination of SbF or by treatment of SbCl with HF. In the latter method the fifth chlorine is removed with difficulty failure to remove the chlorine completely results in contamination of the distilled SbF with Sb(III) (27). 

The interaction of triarylstibines and antimony trichloride or tribromide is a convenient and efficient method for preparing aryldihalo- and diaryUialostibines (104,107,108) ... 

Stibonium Ylids and Related Compounds. In contrast to phosphoms and arsenic, only a few antimony yhds have been prepared. Until quite recendy triphenyl stibonium tetraphenylcyclopentadienyUde [15081 -36-4] C H Sb, was the only antimony yUd that had been isolated and adequately characteri2ed (192). A new method, uti1i2ing an organic copper compound as a catalyst, has resulted ia the synthesis of a number of new antimony yhds (193) ... 

In this method, a metal oxide or hydroxide is slurried in an organic solvent, neodecanoic acid is slowly added, and the mixture is refluxed to remove the water. Salts that are basic can be prepared by using less than stoichiometric amounts of acid. This method has been used in the preparation of metal salts of silver (80) and vanadium (81). The third method of preparation is similar to the fusion process, the difference is the use of finely divided metal as the starting material instead of the metal oxide or hydroxide. This method has been appHed to the preparation of cobalt neodecanoate (82). Salts of tin (83) and antimony (84) have been prepared by the fusion method, starting with lower carboxyHc acids, then replacing these acids with neodecanoic acid. 

This method is used for the determination of total chromium (Cr), cadmium (Cd), arsenic (As), nickel (Ni), manganese (Mn), beiylhum (Be), copper (Cu), zinc (Zn), lead (Pb), selenium (Se), phosphorus (P), thalhum (Tl), silver (Ag), antimony (Sb), barium (Ba), and mer-cuiy (Hg) stack emissions from stationaiy sources. This method may also be used for the determination of particulate emissions fohowing the procedures and precautions described. However, modifications to the sample recoveiy and analysis procedures described in the method for the purpose of determining particulate emissions may potentially impacl the front-half mercury determination. 

Spectrophotometric methods based on an enhancement of the blue color produced on reduction of 12-molybdophosphate (arsenate) in the presence of antimony(III) are widely used for the determination of phosphoms(V) or arsenic(V). However, nature of heteropoly blue, their spectra, mechanism of the reaction are obscure. In addition, mixed POMs were shown as very efficient analytical forms for the determination of P(V) and As(V). 

A simple, rapid and seleetive eleetroehemieal method is proposed as a novel and powerful analytieal teehnique for the solid phase determination of less than 4% antimony in lead-antimony alloys without any separation and ehemieal pretreatment. The proposed method is based on the surfaee antimony oxidation of Pb/Sb alloy to Sb(III) at the thin oxide layer of PbSOyPbO that is formed by oxidation of Pb and using linear sweep voltammetrie (LSV) teehnique. Determination was earried out in eoneentrate H SO solution. The influenee of reagent eoneentration and variable parameters was studied. The method has deteetion limit of 0.056% and maximum relative standard deviation of 4.26%. This method was applied for the determination of Sb in lead/aeid battery grids satisfaetory. 

Samples Analyzed by Inductively Coupled Plasma (ICP) Metals — Where two or more of the following analytes are requested on the same filter, an ICP analysis may be conducted. However, the Industrial Hygienist should specify the metals of interest in the event samples cannot be analyzed by the ICP method. A computer print-out of the following 13 analytes may be typically reported Antimony, Beryllium, Cadmium, Chromium, Cobalt, Copper, Iron, Lead, Manganese, Molybdenum, Nickel, Vanadium, Zinc. Arsenic — Lead, cadmium, copper, and iron can be analyzed on the same filter with arsenic. 

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... 

Some solids are either too soluble, or the solubility does not vary sufficiently with temperature, in a given solvent for direct crystallisation to be practicable. In many cases, the solid can be precipitated from, say, a concentrated aqueous solution by the addition of a liquid, miscible with water, in which it is less soluble. Ethanol, in which many inorganic compounds are almost insoluble, is generally used. Care must be taken that the amount of ethanol or other solvent added is not so large that the impurities are also precipitated. Potassium hydrogencarbonate and antimony potassium tartrate may be purified by this method. 

A similar procedure may also be used for the determination of antimony(V), whilst antimony (III) may be determined like arsenic(III) by direct titration with standard iodine solution (Section 10.113), but in the antimony titration it is necessary to include some tartaric acid in the solution this acts as complexing agent and prevents precipitation of antimony as hydroxide or as basic salt in alkaline solution. On the whole, however, the most satisfactory method for determining antimony is by titration with potassium bromate (Section 10.133). 

If the bulk of the iodate solution is added rapidly, atmospheric oxidation does not present a serious problem, but the method cannot be used in the presence of salts of antimony(III), copper(I), or iron(II). The solution, which should contain for example 0.15 g SnCl2,2H20 in 25 mL, is treated with 30mL of concentrated hydrochloric acid and 20 mL of water and is then titrated in the usual manner with standard potassium iodate solution. 

Antimony pyrogallate, Sb(C6H503). Antimony(III) salts in the presence of tartrate ions may be quantitatively predpitated with a large excess of aqueous pyrogallol as the dense antimony pyrogallate. The method fadlitates a simple separation from arsenic the latter element may be determined in the filtrate from the predpitation of antimony by direct treatment with hydrogen sulphide. 

It should be pointed out that the titrimetric methods described for the determination of antimony (Chapter 10) are to be preferred to the gravimetric methods as they are simpler, more rapid, and quite as accurate. 

Determination of copper as copper(I) thiocyanate Discussion. This is an excellent method, since most thiocyanates of other metals are soluble. Separation may thus be effected from bismuth, cadmium, arsenic, antimony, tin, iron, nickel, cobalt, manganese, and zinc. The addition of 2-3 g of tartaric acid is desirable for the prevention of hydrolysis when bismuth, antimony, or tin is present. Excessive amounts of ammonium salts or of the thiocyanate precipitant should be absent, as should also oxidising agents the solution should only be slightly acidic, since the solubility of the precipitate increases with decreasing pH. Lead, mercury, the precious metals, selenium, and tellurium interfere and contaminate the precipitate. 

Discussion. In acid solution arsenic(III) can be oxidised to arsenic(V) and antimony(III) to antimony(V) by the well-established titration with a solution of potassium bromate and potassium bromide (Section 10.133). The end point for such determinations is usually observed indirectly, and very good results have been obtained by the spectrophotometric method of Sweetser and Bricker.23 No change in absorbance at 326 nm is obtained until all the arsenic)III) has been oxidised, the absorbance then decreases to a minimum at the antimony(III) end point at which it rises again as excess titrant is added. 

This apparatus may also be adapted for what are termed hydride generation methods (which are strictly speaking flame-assisted methods). Elements such as arsenic, antimony, and selenium are difficult to analyse by flame A AS because it is difficult to reduce compounds of these elements (especially those in the higher oxidation states) to the gaseous atomic state. 

Although electrothermal atomisation methods can be applied to the determination of arsenic, antimony, and selenium, the alternative approach of hydride generation is often preferred. Compounds of the above three elements may be converted to their volatile hydrides by the use of sodium borohydride as reducing agent. The hydride can then be dissociated into an atomic vapour by the relatively moderate temperatures of an argon-hydrogen flame. 

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