Oxygen Flash Combustion

This technique analyses the diethyl ether extracts of the extraction liquids prepared as described under method (b). 

Sodium hydroxide 0.01 N - aqueous. Prepare daily by dilution of a standard 0.1 N stock solution. Ensure that the 0.01 N sodium hydroxide solution is protected from contact with atmospheric carbon dioxide. 

Dissolve 0.125 g methyl red in 100 ml absolute alcohol. Dissolve 0.083 g methylene blue (BP grade) in 100 ml absolute alcohol. Use equal volumes of each indicator for each titration. 

Hydrogen peroxide -100 volume. Microanalytical reagent grade quality. 

Percolated water is prepared by percolating distilled water through a mixed resin hed containing Amberlite IR-120(H) and Amberlite IRA-400(OH). This water must he boiled immediately before use and should be used throughout during the Schoniger combustion stage of the analysis. 

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Oxygen flash combustion was performed with 40 mg dried material. Arsenic is extracted out of the flask with 12 M HCl and 20% Kl solution added to reduce As(V). As(III) is extracted completely twice with benzene and reextracted with 0.1 M HCl for determination. The results... 

Flash combustion of the sample in the combustion reactor is a key feature of the NA 1500. It results when the sample is dropped into the combustion reactor which has been enriched with pure oxygen. The normal temperature in the combustion tube is 1020°C and reaches 1700-1800°C during the flash combustion. 

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