Identification and effect of pre-atomisation losses on the determination of aluminium by graphite furnace atomic absorption spectrometry

Abstract

Curvature of calibration graphs for aqueous aluminium determined by wall atomisation graphite furnace atomic absorption spectrometry (GFAAS) is observed for aluminium masses of less than 200 pg. The curvature is attributed to the loss of volatile aluminium-containing molecules before atomisation. The loss, as high as 20%, was quantified by “graph displacement,” and by using a two-step integrated contact (IC) furnace to generate an aluminium signal from the pre-atomisation species and to separate it from the normal atomisation signal. Behaviour of the pre-atomisation portion of the signal when modifier is added and the temperatures at which it is observed are consistent with identifying the signal as arising from the decomposition of the Al(OH)₂ observed previously by mass spectrometry.