Sulfur oxygen flask combustion determination

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%). 

Applications Basic methods for the determination of halogens in polymers are fusion with sodium carbonate (followed by determination of the sodium halide), oxygen flask combustion and XRF. Crompton [21] has reported fusion with sodium bicarbonate for the determination of traces of chlorine in PE (down to 5 ppm), fusion with sodium bisulfate for the analysis of titanium, iron and aluminium in low-pressure polyolefins (at 1 ppm level), and fusion with sodium peroxide for the complexometric determination using EDTA of traces of bromine in PS (down to 100ppm). Determination of halogens in plastics by ICP-MS can be achieved using a carbonate fusion procedure, but this will result in poor recoveries for a number of elements [88]. A sodium peroxide fusion-titration procedure is capable of determining total sulfur in polymers in amounts down to 500 ppm with an accuracy of 5% [89]. 

Oxygen flask combustion Combustion takes place at atmospheric pressure in oxygen water is used as the absorbent. It is suitable for determining sulfur, phosphorus, chlorine, and bromine. 

A method has been described [17] for the determination of chlorine in polymers containing chlorine, fluorine, phosphorus and sulfur, which involves oxygen flask combustion over water, addition of ethanol, and titration to the diphenylcarbazide indicator end point with 0.005 M mercuric nitrate ... 

Method 2.1 Determination of Chlorine in Polymers Containing Chloride and Sulfur and/or Phosphorus and/or Fluorine. Oxygen Flask Combustion - Mercurimetric Titration... 

Method 2.7 Determination of Sulfur in Polymers. Oxygen Flask Combustion - Titration Procedure... 

This oxygen flask combustion photometric titration procedure [40] is capable of determining total sulfur in polymers in amounts down to 50 ppm. 

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. 

The sample, contained in a piece of filter paper and suitably suspended, is rapidly and completely burnt in a closed conical flask filled with oxygen at atmospheric pressure. The products of combustion are allowed to enter a hydrogen peroxide solution. The amount of sulfuric acid formed is determined hy titration with barium perchlorate, using Thorin as the indicator. The equivalence point is obtained photoelectrically by comparing the optical density of the solution with that of a standard reference solution. 

Determination of the level of total sulfur in a rubber can give information on the type of cure system used, for example, elemental sulfur plus accelerator or sulfur donor system, etc. The ISO 6528-1 1992 method — Rubber — Determination of total sulfur content — Part 1 Oxygen combustion flask method is often employed. The principle of the method is oxidation by ignition in an atmosphere of oxygen in the presence of hydrogen peroxide, conversion of sulfur to sulfuric acid and determination of the sulfate by titration with barium perchlorate. The method is... 

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. 

Combustion of the sample in an oxygen combustion flask (Alcino et al., 1965) followed by ion chromatography is an attractive method for the analysis of sulfur in humic substances. Not only does the method require relatively little sample and provide high sensitivity, but it also allows simultaneous determination of halogens. One must be sure that sulfur is not rendered insoluble by ash constituents such as calcium. 

Determination of Combined Sulfur. The sample was decomposed by ignition in an oxygen-filled flask containing 25 ml neutral hydrogen peroxide. The combustion gases were completely absorbed by setting the flask aside for 2 hr. The solution was then boiled to expel carbon dioxide, and the resultant sulfate was determined by alkalimetry. 

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