Sample preconcentration techniques background

Determination of inorganic anions by capillary electrophoresis is critically compared with ion chromatographic determinations on the basis of recent literature in the field. After a very brief summary of the theoretical background, the selection and optimization of the running electrolyte system are discussed, especially in connection with modification of the electroosmotic flow. Preconcentration techniques are surveyed, as are the approaches to the sample introduction and analyte detection. The principal analytical parameters of the determinations are evaluated and illustrated on selected applications described in the literature. 1997 Elsevier Science B.V. 

As indicated above, this method is extremely popular because of its low cost and ease and rapidity of use. The simplest form of AAS is the flame technique which is of rather limited sensitivity. This may often prove suitable for analysis of lead in air and soils, but is insufficiently sensitive to analyse natural waters or most vegetation samples without a prior preconcentration. For these latter samples, or for short-term air samples flameless atomic absorption is required. Flame techniques are relatively free of interference and matrix effects, but in many applications the method of standard additions [1, 2] is necessary to minimize matrix interferences. Flameless AAS is more subject to interference by background absorption and matrix effects than the flame method, and the use of both deuterium background correction and the standard additions method is usually advisable. 

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