Study of the possible benefits of flow injection sample introduction for flame atomic absorption spectrometry

Flow injection techniques for use with atomic spectrometry are briefly reviewed, from which it is apparent that there has been a considerable increase in interest recently in on-line pre-concentration and matrix isolation methods. In addition to the use of immobilised reagents and solvent extraction, methods based on precipitation and collection of the precipitate in the manifold have been reported. The possible benefits of running the nebuliser under starvation conditions both with and without air compensation are examined, together with the benefits of peak-area as opposed to peak-height measurements, claimed in some previous studies to lead to improved detection limits. It is shown that, with a Baird Atomic A3400 nebuliser, the depressive effect of phosphate on calcium may be removed at low flow-rates and that with a Philips SP9 nebuliser the best detection limits are obtained when strategies for maximising the peak height are adopted. Preliminary results for the generation of a volatile metal chelate (copper trifluoroacetylacetonate) as the basis for matrix isolation show a considerable improvement in peak-area sensitivity over conventional nebulisation, although the peak-height sensitivity is similar.