Sample digestion techniques oxygen combustion bombs

The first step in analysing plastics for metals content in polymers by ICP-AES technique is that they must be prepared in solutions that are suitable for nebulization. There are four general methods applicable for sample preparation for metal analysis by ICP-AES and they are solvent dissolution of some plastics dry ashing using a muffle furnace acid digestion using a microwave oven and oxygen bomb combustion. 

Digestion of samples using high pressure oxygen bomb combustion is an excellent technique for sample preparation, particularly trace metal analysis. This technique can be applied to most plastics provided that small sample ( 0.25 g) of fine grain sizes of plastics are used. The solutions obtained are clean and easily analysed for metal content against standards prepared in the same solution added to bomb. 

An improved procedure has been described for atmospheric-pressure combustion of samples from high-purity metals [74]. High-pressure digestion with nitric and hydrofluoric acids 75], [76] and combustion techniques have both been shown to be suitable for the decomposition of samples of silicate-containing materials and fuels. Combustion in this case is carried out either in a stream of oxygen [77] or, to provide a closed system, in an oxygen bomb [78]. Mercury can be satisfactorily determined after prior Wickbold ashing [79]. 

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