Elimination of interferences in the electrothermal atomisation of manganese in atomic absorption spectrometry

Abstract

The effects of inorganic acids and salts which may be present in samples as the result of mineralisation of manganese during wall and platform atomisation have been studied. It was found that the influence of chlorides on manganese in atomic absorption spectrometry (AAS) cannot be eliminated completely using platform atomisation. The proposed chemical modifier consists of an acidic component (phosphoric acid) and a basic component (calcium ions) which improves the sensitivity for the determination of manganese with both wall and platform atomisation. The combination of chemical modifier and platform atomisation gives the greatest sensitivity. Chemical modification increases the sensitivity more than if platform atomisation is used. The accuracy of the determination of manganese by AAS with both wall and platform atomisation are also improved by chemical modification because interferent anions, e.g., chloride, are removed at the pyrolysis stage. The same effect for manganese is seen for other divalent metals, such as magnesium and zinc, in combination with phosphoric acid.