Photographic film and chemicals

The importance of catalysts in our energy and pollution conscious age is growing. Many catalysts depend for their activity on low levels of rather exotic metals, while even trace surface levels of elements such as lead may impair their activity. Thus there is plenty of scope for atomic absorption spectrometry. Many homogeneous catalysts are deposited on an alumina base, thus obtaining dissolution is not always easy and some interference in the air/acetylene flame may be encountered. A leaching procedure (e.g. with nitric acid) to dissolve adsorbed trace metals may be used to circumvent these problems. 

Concern about air pollution has led to extensive investigations of catalysts for automobile exhausts. Elements such as lead (a potential poison), palladium and platinum can be determined after dissolution of the catalyst in acids such as aqua regia. Janouskova et al. [55] reported a detection limit of 0.8 ng for platinum in a catalyst using graphite furnace atomisation and 265.9nm. 

Many catalysts used in chemical synthesis can be treated in the same way, often the nitrous oxide/acetylene flame is used because of the refractory nature of the elements to be determined. Harrington and Bramstedt [56] have determined rhenium in electro-chemical surface catalysts by stripping the coating with molten potassium hydroxide/ potassium nitrate. This melt was extracted with hydrochloric acid, the residue was fused with sodium peroxide for further rhenium determination. Titanium, being the substrate on which the catalyst was coated, was added to the standards, an air/acetylene flame and 343.3 nm were used for the finish. 

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