摘要:

A general system of partial differential equations describing the propagation of signals of finite concentrations in a chromatographic column is derived. These equations are related to the mass-balance equations for the solutes and the carrier gas. The model used assumes that there is no temperature or pressure variation at any point in the column when the signal is eluted, and that the equilibrium between stationary and mobile phases is instantaneous. It is shown that this model, which leads to a tractable set of equations, is generally valid. The solution of this system of equations gives new insight into the phenomena which are responsible for the peak deformations and broadening in preparative scale chromatography.

ISSN:0037-2366    

DOI:10.1080/00372367508058018

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The study of a quasi-ideal chromatography model at finite concentration shows the existence of stable discontinuities, resulting either from sorption or isotherm effects. A set of conditions, illustrated in a diagram, determines the conditions of stability of these discontinuities. Solution thermodynamics shows that there exist three possible modes of peak migration. In all cases a progressive variation of the experimental conditions (pressure or temperature of the column) allows passage from one of these modes to another. One of these three possible modes, the double-shock mode, has not been described previously. It is characterized by front and rear stable discontinuities, and its importance rests on the fact that it corresponds to the minimum band broadening. This mode is observed for a column temperature which is near the boiling point of the solute under the average pressure of the carrier gas. The results also show that the derivation of equilibrium isotherms from the deformation of the peaks obtained with large sample sizes is not valid generally.

ISSN:0037-2366    

DOI:10.1080/00372367508058019

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Resolution of the equations of the quasi-ideal chromatography model at finite concentration is possible in the case of a finite pressure gradient in the column provided the elution does not change the pressure profile and the pressure variation inside the solute band is neglected. A study of the solution shows that there still exists three models of peak migration, as in the zero pressure gradient case, but that the pressure gradient enhances the isotherm effect. It is not possible, however, to account for the effect of pressure gradient by using an average pressure because there is a convolution between the effect of the pressure gradient and a nonlinear isotherm. Analysis of the double-shock propagation mode and the determination of the limiting transition conditions permit accurate measurement of the curvature of the isotherm at infinite dilution. The experimental results (variation of retention time with peak height forn-pentane in squalane) are in excellent agreement with the predictions of the theoretical model.

ISSN:0037-2366    

DOI:10.1080/00372367508058020

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Electrodialytic separation of Ni2+and Co2+cations has been realized by using ion-exchange membranes in the presence of EDTA by preferentially complexing Ni2+(Ni2+concentration = EDTA concentration). The degree of complexation is calculated as a function of the pH and of the concentration by using data taken from the literature. Due to a systematic study of the influence of the different separation parameters (nature of the membranes, flow rate, electric current intensity, pH), the conditions_of_separation have been optimized on a computer, and then pure solutions of nickel and cobalt ions have been obtained experimentally. The decomplexation of Ni2+is accomplished in acidic medium by cooling.

ISSN:0037-2366    

DOI:10.1080/00372367508058021

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A simple and rapid method is described for the analytical separation of gold(III) from iron, cobalt, nickel, ruthenium, rhodium, iridium, palladium, platinum, copper, lead, bismuth, and manganese by solvent extraction with 4-methyl-2-pentanol from hydrochloric acid media. Very few cations and anions interfere.

ISSN:0037-2366    

DOI:10.1080/00372367508058022

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A number of analyses relating to prediction of instantaneous particles position in a gradient solution, gradient capacity and stability in isopycnic banding, ideal number of septa in a zonal rotor, and an optimal density gradient solution for a velocity-sedimentation, etc. has been studied. The purpose of this review is to summarize the present status in analyses and operations of zonal centrifugation and to indicate the introduction of newer techniques which may open up a large number of separation methods by zonal centrifuges.

ISSN:0037-2366    

DOI:10.1080/00372367508058023

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0037-2366    

DOI:10.1080/00372367508058017

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor