Sodium analytical determination, 91-2

Suitable organic solvents, such as ether, benzene, naphtha and the like, are more soluble than in water. This makes it possible to separate them from other substances which may accompany them in the water solution but which are not soluble in the solvents employed. Hence, one application of solvent extraction is the analytical determination of unsaponifiable oils and waxes in admixture with fatty material by submitting the mixture to vigorous saponification with alcoholic potash or, if necessary, sodium ethylate, and to dilute the product with water and extract with petroleum ether. The soaps remain in the aqueous solution while the unsaponifiable oils and waxes dissolved in the ether. The addition of a salt to an aqueous solution prior to extraction is sometimes practiced in some processes. In older processes, SOj is employed in the separation of aromatic and highly saturated hydrocarbons, taking advantage of the much greater solubility of the solubility of the aromatics and... 

In recent years micellar solutions of sodium dodecyl sulfate are being used increasingly in analytical determinations, chemical reactions, and catalysis. 

In comparison with other anionics, little has been published concerning methods of analysis of ether carboxylates. Gerhardt et al. [238] investigated the analytical determination of ether carboxylic acids in reaction mixtures obtained by reaction of nonylphenol ethoxylates with sodium chloroacetate as well as by cyanoethylation by different methods. Several methods, used for other surfactants as well [239], can be used for ether carboxylates. 

The application of the Chelex 100 resin separation and preconcentration, with the direct use of the resin itself as the final sample for analysis, is an extremely useful technique. The elements demonstrated to be analytically determinable from high salinity waters are cobalt, chromium, copper, iron, manganese, molybdenum, nickel, scandium, thorium, uranium, vanadium, and zinc. The determination of chromium and vanadium by this technique offers significant advantages over methods requiring aqueous final forms, in view of their poor elution reproducibility. The removal of sodium, chloride, and bromide allows the determination of elements with short and intermediate half-lives without radiochemistry, and greatly reduces the radiation dose received by personnel. This procedure was successfully applied in a study of... 

Principally the same, but chemically simpler, sequence was used to prepare arylnitro anion-radicals from arylamines, in high yields. For instance, aqueous sodium nitrite solution was added to a mixture of ascorbic acid and sodium 3,5-dibromo-4-aminobenzenesulfonate in water. After addition of aqueous sodium hydroxide solution, the cation-radical of sodium 3,5-dibromo-4-nitro-benzenesulfonate was formed in the solution. The latter was completely characterized by its ESR spectrum. Double functions of the nitrite and ascorbic acid in the reaction should be underlined. Nitrite takes part in diazotization of the starting amine and trapping of the phenyl a-radical formed after one-electron reduction of the intermediary diazo compound. Ascorbic acid produces acidity to the reaction solution (needed for diazotization) and plays the role of a reductant when the medium becomes alkaline. The method described was proposed for ESR analytical determination of nitrite ions in water solutions (Lagercrantz 1998). 

Even prior to Pasteur, alcohol content determination was important as a basis for local, import, and export taxes. Other important applications of accurate wine analysis have been to detect and to accurately determine food additives now there are legal reasons for analyzing wines for sulfur dioxide, organic chloride or bromide, sodium, cyanide, diglucoside pigments, various insecticides, fungicides, etc. Winery control calls for analytical determination of iron, copper, protein, total acidity, pH, tartaric, malic and lactic acids, etc. Finally, quality control... 

In the analytical determination of the hyponitrites, W. Zorn treated soln. of the free acid, or of its salts in cold dil. nitric acid with an excess of silver nitrate, and just neutralized the free acid with ammonia or sodium carbonate. The washed and dried precipitate was weighed as silver hyponitrite, or weighed as metal or chloride. A. Thum treated the aq. soln. of the acid with an excess of a soln. of permanganate, and in 15 minutes added sulphuric acid after standing for another hour the soln. was warmed to 30°, and treated with a known quantity of 0-1A-oxalie acid sufficient to decolorize the permanganate. The excess oxalic acid was determined by permanganate titration. A. Hantzsch and A. Sauer, and... 

The course of this reaction was proved by Hilt et al.42> 54 > who used as copolymerization initiators 14C-labelled sodium and potassium benzoate. The activity of the prepared copolymer is due to the labelled and chemically bound initiator anion. This reaction is analogous to the analytic determination of epoxides by hydrogen halides 59 but instead of inactive halogen hydrine generaled according to Eq. (12), an ionic particle capable of initiating copolymerization is formed. 

The acid hydrolysis of the 2-aryl-1,3,4-oxadiazoles can be used for their analytical determination. The method used is either to break down the compound by heating with hydrochloric acid under reflux to give the acid hydrazide and then to titrate the hydrazide with iodide in bicarbonate solution,68, 69 or to titrate potentiometrically directly with sodium nitrite in a hydrochloric acid medium.128 In this way the acid hydrazide is formed in the first reaction step and is then converted into the insoluble azide by the sodium nitrite. 

The analytical determinations most often made on a polyuronide before it is hydrolyzed are those for uronic acid, pentosan, methyl-pentosan, methoxyl and ash. The percentage of hexosan is usually estimated by difference. When the polyuronide has been obtained as a free acid it can in many cases be titrated with a base. Such metals as sodium, potassium, magnesium, calcium and iron often occur and especially so in plant gums and mucilages. 

Brooks and Norymberski used sodium bismuthate for the analytical determination of adrenocortical hormone side chains of types (l)-(5). A 21-desoxyketol (6) alone is not attacked. Oxidations (l)-(5) can be followed by determination of the... 

The analyses of the dust and salt components have been performed by various methods in our laboratory. Neutron activation analysis was used to determine Na, Mg, Al, Ti, V, Mn, Sc, Fe, Co, Sb, Ce, and Eu in dust (28). Fluoride in dust (and the K value in Table III) was done by photon activation analysis (12, 28). The salt portions of the aerosol and rainwater samples were analyzed for Na, K, Cl, and F. Sodium was determined by neutron activation and atomic absorption, potassium by atomic absorption, chlorine by titration, photon activation, and neutron activation, and fluoride by ion-specific electrode and photon activation (12, 28-30). Two analytical methods were used for Na, F, and Cl in the same samples to determine precision and accuracy. 

Several elements (Zn, Pb, Cuy Ni, Ca, Mg, Fe, and Mn) are determined routinely in water samples using atomic absorption spectroscopy. Sodium and potassium are determined by flame emission. The preparation of the samples the analytical methody the detection limits and the analytical precisions are presented. The analytical precision is calculated on the basis of a sizable amount of statistical data and exemplifies the effect on the analytical determination of such factors as the hollow cathode sourcey the ffamey and the detection system. The changes in precision and limit of detection with recent developments in sources and burners are discussed. A precision of 3 to 5% standard deviation is attainable with the Hetco total consumption and the Perkin-Elmer laminar flow burners. 

The most common method of analytical determination of rubidium is atomic absorption spectroscopy (AAS) or neutron activation analysis (NAA). Chemical methods of analysis for the determination of rubidium are difficult because of the tedious procedures required to effect the separation from the other alkali metals. The beneficial effects of the addition of other alkali metals, particularly potassium, sodium, and cesium, added to interfere with the ionization of rubidium is detailed by many authors [39,53-55]. Recent evaluation of the benefits of these ions in the determination of rubidium in human erythrocytes has concluded that erythrocytes should be diluted 1 50 with potassium to give a final potassium concentration of 10000 ppm. Under these conditions, the sensitivity of absorbance was increased about threefold and rubidium concentrations could be determined in the range 0-60 ppm [56]. 

The aim of the present work is to estimate the linear voltammetry possibilities in oxide-ion analytical determination in FLINAK melt with and without addition of tantalum and boron complex fluorides. Sodium oxide was used as a source of oxygen in the melts. 

In other work, Wittig postulated the dehydrobenzene intermediate and proved its existence through trapping reactions of the Diels-Alder type. He discovered sodium tetraphenylborate, which is now used in the analytical determination of potassium and ammonium ions. His later work involved the chemistry of metalated Schiff bases. This work subsequently led to the development of the concept of directed aldol condensations. 

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