SchOniger combustion flask

The first step in determination of total sulfur in pulp by combustion/ion chromatography entails burning the pulp in a Schoniger combustion flask (Douek and Ing 1989). Combustion of the pulp in an oxygen atmosphere in a platinum boat oxidizes the sulfur to sulfate which dissolves in deionized water at the bottom of the flask. The presence of a few drops of hydrogen peroxide in the deionized water ensures that oxidation to sulfate is complete. 

SchOniger combustion flask 477, 478 seml-bleached pulps 71, 72, 73 Sephadex gels 360,487-489 silylation 290, 293-295, 337, 378,... 

Add to a 500 ml Schoniger combustion flask, 1 ml of 100 volume hydrogen peroxide and 10 ml of recently boiled-out distilled water. Add 0.1 ml each of methyl red and... 

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. 

Deionized water (20 ml) containing a few drops of 30% hydrogen peroxide are placed in the bottom of the Schoniger flask and the flask is filled with oxygen. The combustion flask is introduced into an infrared igniter (available from A.H. Thomas Co.) and the wrapper is ignited. After combustion is complete, the flask is removed and allowed to cool for several minutes. The contents are shaken for 30 s and allowed to stand for about lh to ensure complete absorption. The solution is then transferred into a 100-ml volumetric flask and diluted to the mark with deionized water prior to ion chromatographic analysis. 

For the determination of sulfur contents of residual fuels a variety of procedures are available. The bomb (ASTM D-129, IP 61) and quartz tube (ASTM D-155, IP 63) combustion methods have long been established. Other, more rapid techniques are becoming increasingly available, including high-temperature combustion (ASTM D-1552), X-ray absorption and fluorescence methods, and the Schoniger oxygen flask procedure. 

Traces of chlorine have been determined in polyolefins [17] at levels between 0 and 500 ppm. The Schoniger oxygen flask combustion technique requires a 0.1 g sample and the use of a 1 litre conical flask. Chlorine-free PE foil is used to wrap the sample, which is then supported on a platinum wire attached to the flask stopper. Water is used as the absorbent. Combustion takes place at atmospheric pressure in oxygen. The chloride formed is potentiometrically titrated in nitric acid/acetone medium with 0.01 M silver nitrate solution. 

Combustion Calorimetric bomb (Berthelot), oxygen flask (Schoniger), Wickbold apparatus, cold plasma incinerator, micro-Dumas combustion (CHN analyser), sulfur-specific analysers (S, C, N, O), pyrochemiluminescence... 

Micro amounts of sulfur in polymer are usually determined by oxygen flask combustion, sodium peroxide fusion in a metal bomb followed by titration [30], pyroluminescence [36] or ICP-AES. An oxygen flask combustion photometric titration procedure capable of determining total sulfur in polymers in amounts down to 50 ppm was reported. The repeatability of the sulfur determination in polyolefins in the oxygen flask is 40% at 50 ppm level, improving to 2% at the 1 % level [21]. Crompton [31] has also combined Schoniger flask combustion with a colorimetric procedure for the determination of phosphorous in polymers in various concentration ranges (0.01 to 2%, 2 to 13%). 

For general purpose tracer work, however, and particularly in polymer chemistry, the liquid scintillation counter surpasses all other instruments in its sensitivity and adaptability. There is no question on the author s mind that at the present time such an instrument would be the first choice, particularly where tritium, carbon-14 or sulphur-35 were involved. Samples for assay are dissolved in a phosphor whose major solvent usually consists of toluene, toluene-alcohol, or dioxan. Many polymers and low molecular weight compounds are readily soluble in these solvents. Prospective users should not be deterred by alleged complications due to "variable quench effects" as these effects are readily corrected for via internal or external standards or the channels ratio method (7, 46, 91). Dilution quench corrections, though valid, are tedious and unnecessary. Where samples are insoluble in phosphor they may be suspended (e.g. as gels or as paper cut from chromatograms, etc.) or they can be burnt and the combustion products absorbed in a suitable phosphor solution. A modification of the Schoniger flask combustion technique is particularly suitable for this purpose (43—45). 

Oxygen flask combustion (Schoniger flask) Oxygen bomb combustion Combustion in a dynamic system (Trace-O-Mat) Organic Organic Organic... 

Combustion in Closed Systems Oxygen Flask Combustion (Schoniger)... 

Combustion in an oxygen flask, commonly called the Schoniger technique, offers advantages when readily volatilized elements such as halogens, Se, S, P, B, Hg, As, or Sb are to be determined. The combustion is performed with oxygen in a sealed container and the reaction products are absorbed in a suitable solvent before the reaction vessel is opened. 

The flask-type combustion apparatus of the Schoniger system is commercially available (Mikro K Heraeus, Germany). 

Hilp M (1998) Optimization of iodine determination according to Schoniger — analytical chemistry with l,3-dibromo-5,5-dimethylhydantoin (DBM) Part 1, oxygen flask combustion Part 7 [1,2]. Fresenius J Anal Chem 360 184-191. 

The fluoride ion-selective electrode may be used directly for free inorganic fluoride, while total fluoride is usually obtained after ashing or Schoniger flask combustion, the higher values for the latter indicating that a proportion of the fluorine is bound [160-167]. 

Generally, about 100 mg of a weighed sample are combusted in a 2 litre Schoniger flask containing 10 ml of 0.01 M nitric acid. After the combustion, the flask is allowed to stand for at least 15 minutes with occasional shaking before 5 ml of 0.01 M silver nitrate solution is added. 

A suitable method of mineralization of organic compounds consists, according to Schoniger [for reviews, see 6, 7)], in their combustion in an oxygen filled flask this process is quick, and in it the elements to be detected are not present in a large excess, of other products of mineralization, as in the case of the sodium fusion method. 

Schoniger flask Conical flask fitted with a stopper sealed to platinum gauze, for use in the determination of sulfur, halogens, and so forth by the closed-flask combustion technique. 

When the organic compound to be analyzed contains only carbon, hydrogen, oxygen, and sulfur after closed-flask combustion as described above, the resultant solution will be dilute sulfuric acid. In this case, it is more convenient to use acidimetry as the mode of finish. For this purpose, the solution in the Schoniger flask is transferred into a 100-mL conical flask, boiled for 2 min to remove residual hydrogen peroxide, and then titrated with 0.01 N sodium hydroxide, with methyl red as the indicator ... 

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