Flask Schoniger

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... 

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. 

B. Phosphovanadomolybdate method Discussion. This second method is considered to be slightly less sensitive than the previous molybdenum blue method, but it has been particularly useful for phosphorus determinations carried out by means of the Schoniger oxygen flask method (Section 3.31). The phosphovanadomolybdate complex formed between the phosphate, ammonium vanadate, and ammonium molybdate is bright yellow in colour and its absorbance can be measured between 460 and 480 nm. 

Saturated solutions of some reagents (T) 829 Schoniger oxygen flask see Oxygen flask Schwarzenbach classification 53 Screened indicators 268 Sebacic acid 469 Secondary pH standards 831 Selective ion meters 567 Selectivity coefficient, 559 in EDTA titrations, 312 in fluorimetry, 733 of analytical methods, 12 Selenium, D. of as element, (g) 465 Semi-log graph paper 572 Sensitivity (fl) 834, (fu) 732 Separation coefficient 163, 196 Separations by chromatographic methods, 13, 208. 233, 249... 

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%). 

A sample of dobutamine hydrochloride containing at least 2 mg of chlorine is ignited in a Schoniger flask containing 20 ml of water. Three drops of diphenyl carbazone (5 mg/ml) in methanol are added to the solution of the completely burned sample. Mercuric nitrate, 0.5 N, is then used to titrate this solution to the first sign of rose color, using a 1 ml microburette ... 

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). 

Kuus, K. Y and L. A. Lipp Applicability of the Schoniger Flask Method for Determining Halogens in Organic Materials. Zh. Analit. Khim. (Russ.) 21, 1103 (1966) J. Anal. Chem. USSR (English Transl.) 21, 976 (1966). 

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. 

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. 

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). 

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

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. 

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]. 

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. 

---