Iodine, determination oxygen flask combustion

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. 

Procedures based on separation techniques such as HPLC and IC have been developed for single element analysis for the following two reasons. The first reason is to remove interferents in complicated sample matrices that can give rise to incorrect results, in particular for trace analysis in samples with a high organic content, such as the determination of total iodine in egg products. The second reason is to differentiate the total and free forms of a specific element, such as the determination of the free iodide ion and bounded iodine in food additives. The free iodide ion is determined by direct sample injection into the IC column, whereas the total iodine content is determined after oxygen flask combustion. Thus, both the free and bounded forms of iodine in food samples can be determined. 

An oxygen flask combustion method for the determination of between 2 and 80% of chlorine, bromine and iodine in polymers is described in Methods 2.2 and 2.3 at the end of this chapter. 

Method 2.3 Determination of Up to 80% Chlorine, Bromine and Iodine in Polymers. Oxygen Flask Combustion - Titration... 

METHOD 77 - DETERMINATION OF UP TO 80% CHLORINE, BROMINE AND IODINE IN POLYMERS. OXYGEN FLASK COMBUSTION - TITRATION PROCEDURE. 

This oxygen flask combustion - titration procedure is capable of determining between 2 and 80% of total chlorine, bromine or iodine in polymers. 

The iodine may also be determined by the oxygen-flask combustion method, using 8 mg and titrating with 0 01 N thiosulphate. 1 ml O-OIN = 0-000423 g I. 

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. 

The method described by Merz involves burning the sample in an oxygen-filled flask, and the combustion products are absorbed in dilute iodine solution in which As(III) is quantitatively oxidized to As(V). The arsenic is determined by the molybdoarsenate blue reaction, with hydrazine sulphate as reductant the excess of iodine from the absorber does not interfere. Concentrations of arsenic greater than 10/rg are measured on a filter... 

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