DISCONTINUOUS FLOW-ANALYSIS - GENERATION OF FLUID-FLOWS BY DIFFERENTIAL PUMPING

The work completed to date on the new technique of discontinuous flow analysis (DFA) is reviewed. This differential flow-based solution handling technology makes use of a mechanically driven cam to operate syringe pumps in order to vary and control the flow rates and accelerations of a sample and a reagent or reagents. DFA has already been applied to several problems in analytical chemistry and these are described. The technique is capable of performing extremely fast flow titrations (5 s) with high precision (< 1% rsd). DFA can also be used in an incremental mode for multi-point standard addition, again repetitively, and for gradient work which provides a calibration curve and sample measurement in the one cam cycle. One particularly promising application is in atomic spectroscopy where DFA rivals flow injection analysis (FIA) as a versatile and precise handling procedure for presenting a sample to the spectrometer. There is also considerable evidence from the work discussed in this review that DFA has the potential to be a very useful technique for quality assurance work and for on-line monitoring.