Determination of sulphuric

Ion chromatography has been successfully applied to the quantitative analysis of ions in many diverse types of industrial and environmental samples. The technique has also been valuable for microelemental analysis, e.g. for the determination of sulphur, chlorine, bromine, phosphorus and iodine as heteroatoms in solid samples. Combustion in a Schoniger oxygen flask (Section 3.31 )is a widely used method of degrading such samples, the products of combustion being absorbed in solution as anionic or cationic forms, and the solution then directly injected into the ion chromatograph. 

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 sulphur in mineral sulphides Introduction. The methods to be described apply to most insoluble sulphides. In these the sulphur is oxidised to sulphuric acid, and determined as barium sulphate. Two procedures are available for effecting the oxidation. 

The method [97] discussed in section 12.8.1.1 for the determination of sulphur in soils has been applied to lake sediments. Landers [97] also determined organic sulphur (carbon bonded sulphur and ester sulphate) and inorganic sulphur (sulphate and sulphide) in lake sediments. Some results... 

Readily volatile compounds cannot, as a rule, be tested in this way. As described in the method for the quantitative determination of sulphur, they are heated in a sealed tube to about 200°-300° with fuming nitric acid, and the solution produced is diluted with water and tested for sulphuric acid with barium chloride. 

The determination of sulphur by the Carius method is carried out in the same way as is the determination of halogen, but, in place of the silver nitrate, anhydrous barium chloride is here used. 

The determination of sulphur in the tube with bead packing is carried out in a manner analogous to that employed in the argento-metric determination of halogen (see p. 73). 

A rehable flash distillation unit as described above has many apphcations for AAI methodology, and it can also he used coupled to AAII technology. For the determination of sulphur dioxide in wine and soft drinks it has many advantages over the commercial methods based on a gas membrane. 

The sources of this minute error ere certainly of much less importance than those -which are found to exist in the process by direct separation, especially as the determination of sulphuric acid and magnesia is one of those operations which can bo effected, with the greatest accuracy. 

Determination of Sulphuric Acid.—Hid a. gallon of the water is, as in the preceding instance, evaporated to throe or four ounces, aud acidified chloride of barium is then to be added, and the wholo boiled, and left for twelve or more hours in repose, then filtered, and the sulphate of baryta washed thoroughly and dried, II 6 5 of sulphate of baryta represents 40 of sulphuric acid. 

Fro. 4.—Electrolytic Apparatus for Determination of Sulphur in Organic Compounds. 

A rapid volumetric method for the determination of sulphur is as follows 2 The sulphur is dissolved in a known volume of hot standard sodium hydroxide solution and after cooling is oxidised to sulphate by the addition of hydrogen peroxide the excess of alkali is then titrated with standard acid.3 The method is applicable to gases containing any common sulphur compound except thiophen (e.g. coke oven gas).4... 

Other reagents which may be applied to the volumetric determination of sulphuric acid and sulphates are barium chromate and benzidine. In the case of the former, the solution of sulphate is precipitated by a solution of barium chromate in hydrochloric acid on subsequent neutralisation of the filtrate, a quantity of chromic acid, equivalent to the barium sulphate which has been precipitated, remains in solution and may be estimated iodometrically.6 Benzidine, on the other hand, is an organic base which forms a very sparingly soluble sulphate the solution of mineral sulphate is treated with a solution of benzidine hydrochloride and the precipitated benzidine sulphate removed by filtration when subsequently suspended in pure water the benzidine sulphate undergoes hydrolysis to a sufficient extent to permit titration of the sulphuric acid with standard alkali.7 Lead nitrate may also be... 

The importance of the determination of sulphuric acid and sulphates lies very largely in the fact that sulphur in various forms of combination, and also free sulphur, is frequently determined quantitatively by primary conversion into sulphuric acid or sulphate, followed by actual estimation in the latter form. For example, a convenient volumetric process applicable to the Carius method for determining sulphur in organic compounds is to neutralise the solution of sulphuric acid after removal of the excess of nitric acid by evaporation, and then add silver nitrate, by which the sulphate is converted into silver sulphate. This is separated from the excess of silver nitrate by means of its insolubility in alcohol, and is then estimated by dissolving in dilute nitric acid and titrating the silver with standard thiocyanate solution.3... 

The sample should be sent as rapidly as possible to the laboratory, and when the analysis is not to be carried out immediately the bottles are stored horizontally and in a cool, but not excessively cold, place. Turbid samples are either left for some time and then decanted or filtered prior to analysis, the residue being examined separately if necessary. The determination of sulphur dioxide should be made before filtration and as soon as the bottle is opened. 

The use of pH-sensitive fluorescent indicators as spray reagents has been recently examined for the determination of sulphur-containing pesticides and amino acids separated by TLC [158,159]. The procedure is adapted from a ligand-exchange method of Frei and Mallet [160]. The separated pesticides are brominated directly on the TLC plate. This treatment oxidizes the pesticides and liberates hydrobromic acid as a side product. On... 

Analysis. XV. Determination of Sulphur by the Oxygen-Flask Method. J. Chem. Soc. 1962, 3033. 

Sevcik, J. Selective determination of sulphur, chlorine and nitrogen with a combination of flame photometric and flame ionisation detectors. Chromatographia 4,... 

Brinkmann, H. Gas chromatographic determination of sulphur dioxide in presence of carbon disulphide, hydrogen sulphide, carbon dioxide and inert gas. Chem. Tech. 17, 168(1965). -Anal. Abstr. 13, 3387(1966). 

Variations in the 8 34S values for plants have been summarised by Krouse et al. (1991), these range from -20 to +34%o and are comparable to those reported in sedemintary rocks. It has been found that the sulphur uptake by the plant is mainly from soil sulphate where ambient S02 levels are low. In some cases ambient S02 dominates and the 8 34S values are close to those of the S02. These two uptake mechanisms are a factor in the differing isotope ratios in different parts of an individual plant (Chukhrov et al., 1978). Thus sulphur isotope ratios are helpful in the determination of sulphur sources in the environment. 

Sjostrom E, Enstrom B (1966) A method for the separate determination of sulphur and carboxyl groups in sulphite pulps Sven Papperstidn 69 55-59... 

Dubemet, M., Pennequin, E, Grasset, F. (1995a). Adaptation of the determination of sulphur dioxide total in wines sur sequential analyser Hitachi 111. FV OIV 991. 

Ashworth, M. R. F., The Determination of Sulphur-Containing Groups, Vol. 1. Academic Press, New York, 1972. 

Douek M, Ing J (1989) Determination of sulphur and chlorine in pulp and paper samples by combustion/ion chromatography. J Pulp Pap Sci 15 J72-J78 Glennie DW (1971) Reactions in sulphite pulping. In Sarkanen KV, Ludwig CH (eds) Lignins. 

The coal industry has benefited greatly through the applications of nuclear techniques. Nucleonic gauges and on-stream analysers are now regularly employed for monitoring and controlling the ash and moisture content in coal and coke. Nuclear techniques make possible the on-line determinations of sulphur and nitrogen (the causes for acid rain) in coal both of these are important for pollution control. Hundreds of millions of tonnes of coal are analysed annually by this method, a process which has become routine in the coal industry. 

Davy and Stokes (1977) also reported the determination of sulphur dioxide in the soil air overlying sulphide mineralisation. The levels measured were low, the contrast was poor, the samples were few and the traverses were not repeated. Despite very long sampling times (24-96 h) and deep sample holes (1.5-7.6 m), the results proved to be ambiguous. 

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