Determination barium

Morrison JL, Richardson JM (1996) Preliminary assessment of barium determination in Zinn-waldite ZW-C by X-ray fluorescence spectrometry. Geostds Newslett 20 65-69. 

Thomas RG, Ewing WC, Catron DL, et al. 1973. In vivo solubility of four forms of barium determined by scanning techniques. Amer Ind Hyg Ass J 34 350- 359. 

Barium sulfate may also be used safely as an X-ray contrast medium as its very low solubility is reflected by low toxicity. Likewise, the solubility of barium sulfate in whole body water is insufficient to cause any toxic effects (Barke 1970). The extent of absorption of barium (determined by renal excretion) following administration of barium sulfate preparations ranged from 18 to 35 jg, which was equivalent to an absorption rate of 0.18-0.26% (Clave et al. 1987). 

A much mure troublesome problem occurs when Ihe source of absorption or scattering originates in Ihe sample matrix. In this instance, the power of the transmitted beam P is reduced by the matrix components, but the incident beam power Pq is not a positive error in absorbance and thus concentration results. An example of a potential matrix interference because of absorption occurs in the determination of barium in alkaline-earth mixtures. As shown by the solid line in Figure 8-8, the wavelength of Ihe barium line used for atomic absorption analysis appears in Ihe center of a broad absorption band for CaOH. We therefore anticipate that calcium will interfere in barium determinations, but the effect is easily eliminated by substituting nitrous oxide for air as Ihe oxidant. The higher temperature of the nitrous oxide flame decomposes the CaOH and eliminates Ihe absorption hand. 

Barium determination with the graphite tube technique (Furnace method)... 

For the barium determination, fit the barium hollow cathode lamp and set the monochromator at 553.6 nm. Make fine adjustments to the wavelength setting to give maximum output. Using the correct burner head for acety-lene/nitrous oxide, set up the acetylene/nitrous oxide flame. On instruments where applicable, adjust the gain control to... 

Simple examples of WLN are C2H5OH is Q2 CH3C0 0CH3 is IVOl For branch chain and fused ring structures rules determine the order of notation. It is claimed that over 50% of all organic structures can be represented by less than 25 characters, witherite, BaCOj. The white mineral form of barium carbonate. Used as a source of Ba compounds and in the brick and ceramic industries. 

The following table lists the molar absorptivities for the Arsenazo complexes of copper and barium at selected wavelengths. " Determine the optimum wavelengths for the analysis of a mixture of copper and barium. 

However, the peroxomonophosphate ion decomposes relatively rapidly ia aqueous solution. A mixture of peroxodiphosphoric and peroxomonophoshoric acids can be produced by treatiag a cold phosphoric acid solution with elemental fluorine (qv) (49). Peroxodiphosphoric acid is not produced commercially. Ammonium, lithium, sodium, potassium, mbidium, cesium, barium, 2iac, lead, and silver salts have all been reported. The crystal stmctures of the ammonium, lithium, sodium, and potassium compounds, which crysta11i2e with varyiag numbers of water molecules, have been determined (50). 

Quantitatively, sulfur in a free or combined state is generally determined by oxidizing it to a soluble sulfate, by fusion with an alkaH carbonate if necessary, and precipitating it as insoluble barium sulfate. Oxidation can be effected with such agents as concentrated or fuming nitric acid, bromine, sodium peroxide, potassium nitrate, or potassium chlorate. Free sulfur is normally determined by solution in carbon disulfide, the latter being distilled from the extract. This method is not useful if the sample contains polymeric sulfur. 

Analytical Methods. The official NIOSH recommended method for determining sulfur dioxide in air consists of drawing a known prefiltered volume of air through a bubbler containing hydrogen peroxide, thus oxidising the sulfur dioxide to sulfuric acid. Isopropyl alcohol is then added to the contents in the bubbler and the pH of the sample is adjusted with dilute perchloric acid. The resultant solution is then titrated for sulfate with 0.005 M. barium perchlorate, and Thorin is used as the indicator. 

Sodium thiosulfate is determined by titration with standard iodine solution (37). Sulfate and sulfite are determined together by comparison of the turbidity produced when barium chloride is added after the iodine oxidation with the turbidity produced by a known quantity of sulfate iu the same volume of solution. The absence of sulfide is iadicated when the addition of alkaline lead acetate produces no color within one minute. 

Radiopaque materials are used to determine the location of aspirated dentures and fragments (205,206). Opacifying additives include barium sulfate, barium fluoride, barium or bismuth glasses, and brominated organic monomers and polymers. The incorporation of these additives into the resin base or tooth can adversely affect physical properties. Radiopaque materials meeting the requirement for ANSI/ADA specifications for denture-base polymer have been described (207). 

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. 

The chemical identities of the fission products determine their subsequent redistribution, those elements which are in the gaseous state at the temperature of the operation migrating to the cooler exterior of the fuel rods, and die less voltile elements undergoing incorporation in the fuel rod in solid solution. Thus caesium and iodine migrate to the gas fill which sunounds the fuel rod, and elements such as the rare earths and zirconium are accommodated in solid solution in UO2 without significant migration along the fuel rod radius. Strontium and barium oxidize to form separate islands which can be seen under the microscope. 

Schierholtz and Stevens (1975), Noor and Mersmann (1993) and Chen etal. (1996) determined nucleation rates by integrating the total crystal number formed over a period and related it to an estimate of supersaturation in the precipitation of calcium carbonate, barium carbonate and barium sulphate respectively. 

As catalyst for the Rosenmund reaction palladium on a support, e.g. palladium on barium sulfate, is most often used. The palladium has to be made less active in order to avoid further reduction of the aldehyde to the corresponding alcohol. Such a poisoned catalyst is obtained for example by the addition of quinoline and sulfur. Recent reports state that the reactivity of the catalyst is determined by the morphology of the palladium surface." ... 

Poloxamers are used primarily in aqueous solution and may be quantified in the aqueous phase by the use of compleximetric methods. However, a major limitation is that these techniques are essentially only capable of quantifying alkylene oxide groups and are by no means selective for poloxamers. The basis of these methods is the formation of a complex between a metal ion and the oxygen atoms that form the ether linkages. Reaction of this complex with an anion leads to the formation of a salt that, after precipitation or extraction, may be used for quantitation. A method reported to be rapid, simple, and consistently reproducible [18] involves a two-phase titration, which eliminates interferences from anionic surfactants. The poloxamer is complexed with potassium ions in an alkaline aqueous solution and extracted into dichloromethane as an ion pair with the titrant, tet-rakis (4-fluorophenyl) borate. The end point is defined by a color change resulting from the complexation of the indicator, Victoria Blue B, with excess titrant. The Wickbold [19] method, widely used to determine nonionic surfactants, has been applied to poloxamer type surfactants 120]. Essentially the method involves the formation in the presence of barium ions of a complex be-... 

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