POSTCOLUMN REACTION DETECTION AND FLOW-INJECTION ANALYSIS

Post-column derivatization with chemical reaction detection (CRD) and flow injection analysis (FIA) use the same principle, viz, reaction in a flow system. For CRD, dispersion must be minimized so as to maintain the separation achieved. In FIA, dispersion is required to mix the reagent and solute. It has been demonstrated that by using low-dispersion knitted capillaries and various modifications of the FIA principle (forced mixing in a branched system; inverse FIA; plug injection of solute and reagent in an inert carrier), the detection limit can be improved. In plug injection, one can also use coloured reagents and solutes to reduce reagent consumption.