"MULTI-ANALYTE DETERMINATION TECHNIQUES IN FIA - A CRITICAL OVERVIEW"

Bo Karlberg
Department of Analytical Chemistry, Stockholm University, SE-10691
Stockholm (Sweden)
bo.karlberg@anchem.su.se

Flow Injection Analysis, FIA; is a mature technique enabling mechanization and automation of wet chemistry batch methods. In many FIA applications just one analyte at a time is determined in the sample. This is in contrast to, for example, chromatographic techniques where a large number of analytes can be determined in just one run. However, there are various ways to extend the versatility of the FIA technique so that multi-analyte determinations can be realized. This presentation will critically examine some of these ways.
The following multi-analyte FIA techniques will be considered
1. Utilization of a multi-analyte detector, e.g. AAS or ICP
2. Two manifolds sharing one detector, post-valve splitting
3. “Multichemistry” within each injected sample, one detector
4. Analyte separation, one detector
The first approach, i.e. the use of a detector having selective multi-analyte detection capability, is today an established approach and there are several commercial instruments on the market based on this principle.
The second and the third approaches, presented and introduced rather early in the FIA history, have not yet reach a level of practical utility for routine purposes.
The final approach, analyte separation, is a relatively young accomplishment but it has a promising potential. Current on-going research will probably improve and make it a valuable supplement to the traditional chromatographic techniques routinely used today. FIA and its successor SIA, Sequential Injection Analysis, are very flexible techniques in that the flow can be fully programmed with respect to rate and direction. The combination of FIA with separation techniques such as the use of monolithic columns and capillary electrophoresis will finally be reviewed.

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