Decisive problems of zone-circulating flow injection analysis and its solution

Automated system to acquire fluorescence, polarization and anisotropy maps within liquid flows

“…It is even possible that a certain degree of slip velocity occurs at the interface. It is likely that the dispersion [30] will also decrease as the molecular domains become more laminar. When the SDS concentration is increased (® gure 6C), the polarization and anisotropy stay almost identical.…”

Flow-injection responses of diffusion processes and chemical reactions

“…The extension of the segment may then be visualised as an initial length of the segment that expands both in the forward and in the backward direction during¯ow, as a result of simple diusion (Eq. In a system with modi®ed Poiseuille¯ow, Narusawa [9] also introduced concentration gradients at the front and at the tail of the segment which account for the curve of zone-circulating FIA (ZCFIA); however, the time of arrival of the leading edge in ZCFIA does not ®t the results of the present experiments (Fig. Within the core of the segment, and at a given time, there was no concentration gradient, i.e., the absorbance was constant within the inner core.…”

“…A FIA peak may then be described without including the concepts of microturbulence and radial diusion [9]. A FIA peak may then be described without including the concepts of microturbulence and radial diusion [9].…”

“…Korenaga et al [8] proposed a model of pure Poiseuille¯ow with and without molecular diusion and they predicted that the tail of the FIA signal decreases as the reciprocal of the time. Narusawa [9] extended the FIA model of Poiseuille¯ow by including axial dispersion and axial diusion as well as radial dispersion and radial diusion. A model proposed by Vanderslice et al [10] included detailed studies of the diusion process which is founded on the convective-diusion equation and, in this treatment, the time of arrival of the peak leading edge as well as the residence time become proportional to the square of the channel (tube) radius.…”

Indications of Segmental Flow in Straight Pipes by Flow Injection with Spectrophotometric Detection

“…By assuming pure Poiseuille behaviour of the £ow, Korenaga et al [4] found that very pointed peaks were predicted and that the tail of the signal was proportional to reciprocal time (1/t), thus producing long tails to the observed FIA peak. When di¡usion was added as an overlay to the case of pure Poiseuille £ow, more realistic FIA peaks were obtained but, however, still with a 1/t dependence of the tail prevailing [4,12]. Vanderslice et al [5,6] performed a detailed calculation, based on Taylor's convection-di¡usion equation [13,14], of the three-dimensional £ow pattern where the concentration distribution was established of dye molecules within an injected bolus as a function of time and distance.…”