A method for removal of chloride interference in determination of aluminium by atomic-absorption spectrometry with a graphite furnace

Methods for removal of the chloride interferences in determination of aluminium by atomic-absorption spectrometry with a graphite furnace have been investigated. Two mechanisms of chloride interference have been established. The first arises from co-ordination of the chloride to aluminium. This interference can be removed by preventing the co-ordination. The other is due to co-existing chloride salts remaining until the atomization step. This interference can be removed by volatilizing the chloride or by converting it and/or aluminium chloride into another substance such as the oxides before the atomization step. The tetra-ammonium salt of EDTA is very suitable as an additive to overcome chloride interference because of its ability to co-ordinate aluminium and other cations, and also its effect when heated.