COMMUNICATION 1125 CommunicationMaterial for publication as a Communication must be on an urgent matter and be of obvious scienti$c importance. Rapidity of publication is enhanced if diagrams are omitted, but tables and formulae can be included. Communications should not be simple claims for priority: this facility for rapid publication is intended for brief descriptions of work that has progressed to a stage at which it is likely to be valuable to workers faced with similar problems. A fuller paper may be offered subsequently, i f justified by later work.Manuscripts are not subjected to the usual examination by referees and inclusion of a Communication is at the Editor's discretion.

No abstract

The essential features of flow injection analysis are described and the use of flow injection methodology for sample introduction for flame atomic-absorption spectrometry is briefly reviewed. A flow injection analogue of the standard additions method has been devised and applied to the analysis of chromium in some BCS standard steels. The results showed good agreement with the certificate values. The use of a concentration gradient forming mixing chamber t o provide a novel method of rapid, single-standard Calibration is described and the results of preliminary experiments with magnesium show the method to be viable. The potential usefulness of both methods is critically evaluated.

The determination of chromium in steel by atomic-absorption spectrometry is briefly reviewed and the basis of the flow injection standard additions method explained, in which the novel configuration of using the sample as the carrier stream is employed. The effects of iron, fuel to oxidant ratio and dissolution procedure were investigated and a procedure is described that allows a conventional instrument-optimising strategy to be used, requires no releasing agents and uses pure chromium standard solutions. The selection of appropriate flow injection conditions is discussed in the light of the single well stirred mixing chamber model for dispersion. The application of the method is demonstrated by the analysis of six British Chemical Standard steels.

The flow injection introduction of samples that would be difficult by conventional nebulisation owing to dissolved solid content, viscosity or quenching effects on flame reactions is demonstrated. The various ways of achieving sample dilution by control of volume injected, tube dimensions and flow-rate are discussed and a manifold described for producing solutions for calibration purposes and diluting off-range samples. The important characteristics of the nebuliser and instrument for flow injection work are evaluated. A simple manifold for investigating interference effects is described and its use illustrated for some well known effects. The possibilities of achieving pre-treatment by solvent extraction and extension to include indirect methods are discussed and the role of flow injection procedures in the method development for, and the extension of the range of application of, flame atomic-absorption spectrometry is critically evaluated.