Heterogeneous Samples Viscosity and Surface Properties

For determination of an unknown analyte in whole blood (containing typically 40% hematocrit) this will pose a problem, unless the instrument 

The above considerations reveeil that FIA has yet untried capability for determination of suspended matter in liquid samples. Furthermore, hydrodynamic effects on particles of different size and shape might lead to their rough separation or characterization. Much still has to be done both theoretically and experimentally in this area, related to field flow fractionation. 

The influence of the properties of the wall materials, such as wettability and roughness, have not yet been considered. Since the surface/volume ratio increases with decreasing tube diameter, these material characteristics, together with the wall absorptive capacity for analytes, are indeed of importance and their future study will be, undoubtedly rewarding and revealing. 

There are few investigations of the temperature effect on the dispersion and chemical kinetics in the FIA system. Since an increase in temperature increases molecular diffusion—and thus radial mass transfer—the physical dispersion will decrease with increasing temperature. When the contribution of external forces on the radial mass transfer is minimized, as in straight very narrow tubes, the temperature effect should be greatest, and it should decrease in reactors with progressively distorted geometry. Betteridge et al. have simulated the temperature effect by a random walk 

Levenspiel, Chemical Reaction Engineering, 2nd. ed. Wiley, New York, 1972. 

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