caa a22 4500 467996326 CHVBK 20180323112558.0 cr unu---uuuuu 170328e19900101xx s 000 0 eng 10.1007/BF01244494 doi (NATIONALLICENCE)springer-10.1007/BF01244494 Stopped-flow injection analysis. The influence of diffusion on dispersion of normal and reverse flow injection [Elektronische Daten] [Yecheskel Israel, Ramon Barnes] A relationship is derived to enable the comparison of the dispersion heights of normal and reverse flow injection analysis (FIA). A single channel flow system is employed in the absence of a chemical reaction. The stopped-flow injection method is used to probe the influence of molecular diffusion on the overall dispersion of normal and reverse FIA, which appeared to demonstrate fundamentally different diffusion behaviors. Small discrepancies are observed between the dispersion heights, which are enhanced by the stopped-flow period, especially when unmatched matrix ionic compositions of the indicator and counter solutions were involved. For these conditions, the diffusion flux rate is enhanced considerably, displaying a peak, in addition to the transient, for both methods. The influence of diffusion on the dispersion characteristics of normal and reverse FIA is discussed theoretically. Diffusion in the proposed model is postulated to oppose dispersion by convection. The latter initiates concentration gradients in the injection zone and propagates it with flow time over the dispersion zone profile. The diffusion flux then reacts in order to confine the indicator dispersion for normal FIA and to enhance it for reverse FIA. This model is consistent with the experimental results and accounts for most of the phenomena encountered. Probably owing to the influence of secondary flow phenomena, the use of coiled tubes has suppressed the effects of diffusion on the overall dispersion behavior. Springer-Verlag, 1990 stopped-flow injection analysis nationallicence flow injection analysis nationallicence reverse flow injection analysis nationallicence dispersion diffusion nationallicence Israel Yecheskel Department of Chemistry, Lederle Graduate Research Center, University of Massachusetts, 01003-0035, Amherst, MA, USA aut Barnes Ramon Department of Chemistry, Lederle Graduate Research Center, University of Massachusetts, 01003-0035, Amherst, MA, USA aut Microchimica Acta Springer-Verlag 100/1-2(1990-01-01), 17-30 0026-3672 100:1-2<17 1990 100 604 https://doi.org/10.1007/BF01244494 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01244494 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Israel Yecheskel Department of Chemistry, Lederle Graduate Research Center, University of Massachusetts, 01003-0035, Amherst, MA, USA aut NATIONALLICENCE 700 1- Barnes Ramon Department of Chemistry, Lederle Graduate Research Center, University of Massachusetts, 01003-0035, Amherst, MA, USA aut NATIONALLICENCE 773 0- Microchimica Acta Springer-Verlag 100/1-2(1990-01-01), 17-30 0026-3672 100:1-2<17 1990 100 604 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer