Kent K. Stewart

Laminar dispersion in flow-injection analysis.

Simple expressions are given for the dispersion and the travel times of samples in simple flow-injection analysis systems. The sum of these two quantities is the total residence time of the sample in the system. The expressions are based on numerical solutions of the diffusion-convection equation. Preliminary experiments are in agreement with the derived simple expressions, as are peak curve shapes. Diffusion coefficients can be obtained in a straightforward manner.

Flow-injection analysis: A review of its early history

A review is given of the development of flow-injection analysis, which seeks to establish the various lines of research which led to the present form of the technique.

A method for automated analyses of the activities of trypsin, chymotrypsin and their inhibitors

Abstract Methods for the automated analyses of the activity of trypsin and chymotrypsin and their inhibitors using l -BAPA and l -GPNA, respectively, as substrates are described.

Automated titrations: the use of automated multiple flow injection analysis for the titration of discrete samples.

Introduction In 1974 Fleet and Ho 1] successfully demonstrated an automated continuous flow titration system using a reagent gradient. This system had a throughput of only ten samples per hour, but it was significant since it demonstrated the principles for titration of discrete samples in continuously flowing streams. Nagy et al. [2,3 ]have also demonstrated a similar approach. In 1977, Ruzicka et al. [4] described the principles and an apparatus for the automated titration of manually

Affinity chromatography of trypsin inhibitors on trypsinogen-agarose exchangers

Dlouha and Keil [ 1,2] have reported that two trypsin inhibitors complex with trypsinogen as well as with trypsin. We have prepared trypsinogen-agarose and trypsin-agarose columns ‘and have compared the chromatographic behaviour of crude peanut trypsin inhibitor (PTI) and Kunitz soybean trypsin inhibitor (SBTI) on these columns. Only the PTI was bound to the trypsinogen-agrose columns while both PTI and SBTI were bound to the trypsin-agarose columns. The PTI could be eluted from the trypsinogen-agarose columns under milder conditions than from the trypsin-agarose columns.

Microcomputer control and data system for automated multiple flow injection analysis.

Introduction Flow injection analysis has been shown to be a versatile technique for the analyses of many types of samples using unsegmented continuously flowing streams. Several recent reviews have discussed a variety of aspects of this field 1-5]. The automated version of flow injection analysis (usually called automated multiple flow injection analysis or AMFIA) is attractive for those laboratories processing large numbers of samples or which require good precision, and several workers have been exploring this type of flow injection analysis [6-25]. There are three general types of AMFIA systems (Figure 1): the standard configuration with low or medium dispersion, the titration system with the large dispersion and the dilution system with low dispersion [22]. Each type of AMFIA configuration requires precise control of the sample tray, probe and sample injection valve. The dilution system also requires the operation of a fraction collector. Data must be acquired and processed by both the standard and titration systems. In this communication methods are described for the automation of all three types of AMFIA systems. The system described uses the Rockwell AIM-65 microcomputer, some associated electronics and layered user-oriented software. This work is a continuation of earlier efforts to provide full automation of AMFIA systems [22,23]. Malmstadt et al and Slanina et al have also described the use of computers for the control of FIA systems 19,24,25 ].

Thin Film Dialysis

Publisher Summary This chapter discusses the thin film dialysis with respect to theory, experimental methods, applications in preparative and analytical work, and the future of the technique. If a solution is dialyzed, its components are subjected to separation processes that are based upon differential diffusion rates through a semipermeable membrane. Thin film dialysis minimizes the contribution of free solution diffusion and can yield very efficient dialysis. Most of these thin film dialyzers are designed for very rapid salt removal and/or buffer exchange, and are characterized by very small ratios of retentate volume to diffusate volume. The chapter also discusses thin film dialyzers, such as analytical dialysis cell, and thin film countercurrent dialyzers. Thin film dialysis membranes should be flexible, have a uniform mechanical strength, low ionic charge, and a polarity compatible with the solvent to be studied. Thin film dialysis can be used in almost any experimental situation in which more classical dialysis techniques are normally used, such as techniques in purification and separation, binding and hydrogen exchange studies, and the measurement of solute size and conformation. However, the present dialysis theory is not completely satisfactory. Though, the qualitative aspects of the theory predict the dialysis behavior of solutes of similar chemical nature, but do not predict a priori the dialysis behavior of solutes of dissimilar chemical nature. The theory of thin film dialysis, thus, needs further development, and further development of the apparatus and membranes is also needed.