Sulphite, determination

Fig.3. DP polarogram of sulphite determination in a research compound. First signal corresponding to 150 A g/ml sodium pyrosulfite.

Adeloju SB, Shaw SJ, and Wallace GG (1994) Polypyrrole-based amperometric biosensor for sulphite determination. Electroanalysis 6 865-870. 

Sulphide, determination of 58,59, 77-79, 82, 85, 86,208,218,406,413 Sulphite, determination of 219 Sulphonated polyphenols, determination of 205 p-Sulphonyl carboxy salts, determination of 202 Sulphonylurea herbicides, determination of 182,183,186... 

The aim of this work is the development of pyrene determination in gasoline and contaminated soils. For this purpose we used room temperature phosphorescence (RTP) in micellar solutions of sodium dodecylsulphate (SDS). For pyrene extraction from contaminated soils hexane was used. Then exttacts earned in glass and dried. After that remains was dissolved in SDS solution in the presence of sodium sulphite as deoxygenation agent and thallium (I) nitrate as heavy atom . For pyrene RTP excitation 337 nm wavelength was used. To check the accuracy of the procedures proposed for pyrene determining by RTP, the pyrene concentrations in the same gasoline samples were also measured by GC-MS. 

The determination of citral in lemon-grass oil by the neutral sulphite absorption process ves results some 4 per cent, lower than those obtained by the bisulphite method, but the latter is that usually adopted in commerce, though, as alreadv stated, the former is official in the new Britiih Pharmacopmia. 

Procedure. Dissolve 0.0079 g of pure lead nitrate in 1 L of water in a graduated flask. To 10.0 mL of this solution (containing about 50 p.g of lead) contained in a 250 mL separatory funnel, add 75 mL of ammonia-cyanide-sulphite mixture (Note 1), adjust the pH of the solution to 9.5 (pH meter) by the cautious addition of hydrochloric acid (CARE ), then add 7.5 mL of a 0.005 per cent solution of dithizone in chloroform (Note 2), followed by 17.5 mL of chloroform. Shake for 1 minute, and allow the phases to separate. Determine the absorbance at 510 nm against a blank solution in a 1.0 cm absorption cell. A further extraction of the same solution gives zero absorption indicative of the complete extraction of the lead. Almost the same absorbance is obtained in the presence of 100 pg of copper ion and 100 pg of zinc ion. 

In determinations of sulphurous acid and sulphites, excess of standard 0.05M iodine is diluted with several volumes of water, acidified with hydrochloric or sulphuric acid, and a known volume of the sulphite or sulphurous acid solution is added slowly and with constant stirring from a burette, with the jet close to the surface of the liquid. The excess of iodine is then titrated with standard 0.1M sodium thiosulphate. Solid soluble sulphites are finely powdered and added directly to the iodine solution. Insoluble sulphites (e.g. calcium sulphite) react very slowly, and must be in a very fine state of division. 

Determination of sulphite by oxidation to sulphate and precipitation as barium sulphate Discussion. Sulphites may be readily converted into sulphates by boiling with excess of bromine water, sodium hypochlorite, sodium hypobromite, or ammoniacal hydrogen peroxide (equal volumes of 20-volume hydrogen peroxide and 1 1 ammonia solution). The excess of the reagent is decomposed by boiling, the solution acidified with hydrochloric acid, precipitated with barium chloride solution, and the barium sulphate collected and weighed in the usual manner (Section 11.72). 

Conversion of thiosulphate to sulphate and determination as barium sulphate Discussion. Thiosulphates are oxidised to sulphates by methods similar to those described for sulphites (Section 11.74), e.g. by heating on a water bath with an ammoniacal solution of hydrogen peroxide, followed by boiling to expel the excess of the reagent. The sulphate is then determined as barium sulphate, BaS04. 

Obtemperanskaya and Kareva25 determined a, /J-unsaturated ketones and sulphones by adding sodium sulphite to the sample in p-dioxan. After 5-10 min they titrated with standard sulphuric acid potentiometrically or to thymolphthalein ... 

Gramstad and coworkers78 studied the formation of association complexes between CHC13 and N, N-disubstituted amides, four alkyl sulphoxides and diethyl sulphite in CC14 by following the JH NMR. The association constants (Afass) were determined by equation ll79,... 

In the course of this study, the authors determined /Lvalues for dibenzyl, methyl phenyl, methyl p-nitrophenyl, di-p-tolyl, di-isopropyl and tetramethylene sulphoxides and for diethyl, dipropyl and dibutyl sulphites. The /Lscales are applied to the various reactions or the spectral measurements. The /Lscales have been divided into either family-dependent (FD) types, which means two or more compounds can share the same /Lscale, family-independent (FI) types. Consequently, a variety of /Lscales are now available for various families of the bases, including 29 aldehydes and ketones, 17 carboxylic amides and ureas, 14 carboxylic acids esters, 4 acyl halides, 5 nitriles, 10 ethers, 16 phosphine oxides, 12 sulphinyl compounds, 15 pyridines and pyrimidines, 16 sp3 hybridized amines and 10 alcohols. The enthalpies of formation of the hydrogen bond of 4-fluorophenol with both sulphoxides and phosphine oxides and related derivatives fit the empirical equation 18, where the standard deviation is y = 0.983. Several averaged scales are shown in Table 1588. 

The chromic acid oxidation of dithionic acid is independent of oxidant concentration and its rate is equal to that of the acid-catalysed hydrolysis to sulphite and sulphate, which must therefore constitute the rate-determining process . ... 

Feubolt, R. and Klein, H., Determination of sulphite and ascorbic acid by high-performance liquid chromatography withe electrochemical detection,. Chromatogr., 640, 271, 1993. 

The crude product contains isomers other than that required and also nitrated phenolic compounds resulting from side reactions. The usual method of purification is to treat the crude product with sodium sulphite, which converts asymmetric trinitro compounds to sulphonic acid derivatives, and to wash out the resulting soluble products with alkaline water. The purity of the product is determined by the melting point, the minimum value for Grade I TNT commonly being 80-2°C. Unless adequate purity is achieved, slow exudation of impurities can occur during storage and the TNT then becomes insensitive. 

Hlavay J., Guilbault G.G., Determination of sulphite hy use of a fiber-optic biosensor based on a chemiluminescent reaction, Anal. Chim. Acta 1994 299 91-96. 

Phosphorescence can also be detected when the phosphor is incorporated into an ionic micelle. Deoxygenation is still required either by degassing with nitrogen or by the addition of sodium sulphite. Micellestabilized room-temperature phosphorescence (MS RTP) promises to be a useful analytical tool for determining a wide variety of compounds such as pesticides and polyaromatic hydrocarbons. 

Jensen et al. [45] applied the method described in section 9.1.2.1 for the determination of DDT and polychlorobiphenyls in sulphur containing sediments to the analysis of sludges. The results in Fig. 9.7 show the beneficial effects of pretreatment of the sewage with tetrabutyl ammonium sulphate-sodium sulphite reagent on the recovery of DDT and polychlorobiphenyls from a digested sewage sludge sample. 

Japenga et al. [56] determined polychlorinated biphenyls and chlorinated insecticides in River Elbe estuary sediments by a procedure in which the sediments were pretreated with acetic acid, mixed with silica and Soxhlet-extracted with benzene/hexane. Humic material and elemental sulphur were removed by passing the extract through a chromatographic column containing basic alumina, on which sodium sulphite and sodium hydroxide were adsorbed. Silica fractionation was followed by gas chromatography to analyse chlorinated pesticides, polychlorinated biphenyls and polyaromatic hydrocarbons. Recovery experiments with standard solutions gave recoveries of 90-102%. 

Develop and validate methodology suitable to determine fate of sulphiting agents in foodstuffs under varying conditions. 

Sulphite which may be added to foods, beers and wines as an antioxidant or anti-browning agent can be determined by IC with an ion-exclusion column and... 

This technique has been established for many years particularly for water, soil and feeding-stuff analysis, where a large number of analyses are required for quality control or monitoring purposes. A number of applications have been published for food additives including aspartame (Fatibello et al., 1999), citric acid (Prodromidis et al., 1997), chloride, nitrite and nitrate (Ferreira et al., 1996), cyclamates (Cabero et al., 1999), sulphites (Huang et al., 1999 AOAC Int, 2000), and carbonate, sulphite and acetate (Shi et al., 1996). Yebra-Biumm (2000) reviewed the determination of artificial sweeteners (saccharin, aspartame and cyclamate) by flow injection. 

There is increasing interest in the use of specific sensor or biosensor detection systems with the FIA technique (Galensa, 1998). Tsafack et al. (2000) described an electrochemiluminescence-based fibre optic biosensor for choline with flow-injection analysis and Su et al. (1998) reported a flow-injection determination of sulphite in wines and fruit juices using a bulk acoustic wave impedance sensor coupled to a membrane separation technique. Prodromidis et al. (1997) also coupled a biosensor with an FIA system for analysis of citric acid in juices, fruits and sports beverages and Okawa et al. (1998) reported a procedure for the simultaneous determination of ascorbic acid and glucose in soft drinks with an electrochemical filter/biosensor FIA system. 

The simple aldehydes react with neutral sulphites to form salts of aldehydesulphurous acids. In this reaction free alkali is formed, and the aldehyde content of a solution can also be determined in this way if the alkali is titrated. 

The elements present in a host of pharmaceutical substances are determined quantitatively by atomic absorption spectroscopy, for example Pd in carbenicillin sodium Cu, Pb and Zn in activated charcoal Fe in ascorbic acid Ag in cisplatin Ph and Zn in copper sulphate Zn in glucogen Zn in insulin Pb in oxprenolol hydrochloride Ni in prazosin hydrochloride Zn in sodium sulphite heptahydrate, and Cd and Pb in zinc oxide. 

Chloride ion-selective electrodes The most important region of application is the determination of chlorides in waters, including sea water (for a review, see [167]), in serum [110,112,371] (review in [167]) and in soil [151,219,341], The determination of chloride ions in sweat made screening for cystic fibrosis possible in new-born babies (review, [45,55a, 262]). Br , I and S " interfere in the determination of chlorides in phosphate rocks [81]. Sulphite can be determined directly using an electrode with an Hgj CI2 - HgS membrane [398] on the basis of the reaction... 

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