摘要:

RMvalues of a number of phenols (cresols, xylenols, chlorophenols, hydroxynaphthalenes) have been determined for numerous solvent systems of the type, weakly polar solvent/formamide. To determine a quantitative scale of extraction strengths,RM-solvent spectra have been plotted using a modified method of Rohrschneider and Littlewood. 2-Methylquinoline, used in previous investigations as a reference solute for nitrogen bases, has been found unsuitable for phenols, and much more regular spectra have been obtained with 1-naphthol as the reference compound. The experimental results indicate that the extraction strengths of solvents cannot be characterized by a single series. Much more satisfactory results are obtained when two series are determined, based on the partition chromatographic parameters of two solutes of opposite H-bonding properties, e.g., 2-methylquinoline and 1-naphthol. For many of the phenols, linearRM-solvent spectra are obtained when the solvents on the abscissa are arranged to give a linear spectrum for 1-naphthol, so that the spectra can be used to predict chromatographic parameters of related solutes.

ISSN:0037-2366    

DOI:10.1080/00372367008068434

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

RM-solvent spectra have been determined for two homologous series of solutes: 4-pyridyl alkyl ketones and 4-pyridyl alkyl alcohols. The substitution of the carbonyl group by the secondary hydroxyl group had little effect on the extraction strength of the solvents of class N and A; however, for electron donor solvents a marked increase of extraction was observed, the shift of the position of solvents in the spectra being approximately constant for aqueous systems. Scales of extraction strengths for various reference compounds have been compared.

ISSN:0037-2366    

DOI:10.1080/00372367008068435

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

All techniques that may be classified at present as “adsorptive bubble separation methods” are described; their relationship to one another is displayed in a schematic diagram which is based on a previous publication.

ISSN:0037-2366    

DOI:10.1080/00372367008068436

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Foam separation of radioruthenium as Ru(IV) and RuNO(III) by the surface-active agents dodecylamine and gelatin from aqueous solutions has been studied. The multistage separation of Ru(IV) with dodecylamine was effective and more than 99% of Ru(IV) has been separated from the solution.

ISSN:0037-2366    

DOI:10.1080/00372367008068437

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

This introductory review explains in simplest terms the separation mechanism in GPC and the concept of size as its discriminant. Sample molecules permeate the gel to different degrees depending on their size and are kept out of the solvent stream in the interstices in correspondingly different time ratios. For rigid molecules the size is determined either by the volume or by the most prominent linear dimension. A better approximation seems to be Giddings's “mean external length.”

ISSN:0037-2366    

DOI:10.1080/00372367008068438

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Proper selection of the column packing material is an essential part of a successful gel permeation analysis. Generally the desirable properties of a packing are good chemical, thermal, and mechanical stabilities combined with good resolution and low resistance to liquid flow. Pore size distribution, particle size distribution, polar characteristics, as well as other physical parameters play a role in how well a packing will perform. This paper describes the different types of column packings which are commercially available, as well as briefly mentioning several packings used on an experimental scale. Physical characteristics of the various packings are compared. Suggested uses along with some limitations are given.

ISSN:0037-2366    

DOI:10.1080/00372367008068439

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The basic instrumentation required for gel permeation chromatography are described. The various choices for sample injectors, pumping systems, detectors, and recording techniques are discussed and critically evaluated. Column choice, construction, etc., are omitted since these items are very well covered by other Symposium papers.

ISSN:0037-2366    

DOI:10.1080/00372367008068440

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Various mathematical approaches to correct instrumental spreading in GPC are summarized. The basic equation describing the spreading correction is identical to that used in X-ray diffraction for correcting its instrumental spreading. In GPC, however, artificial oscillation is easily induced in the solution of the basic equation. This difficulty is partially overcome by data smoothing procedures.

ISSN:0037-2366    

DOI:10.1080/00372367008068441

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A general shape function is proposed for describing the instrumental spreading behavior in gel permeation chromatography (GPC) columns due to axial dispersion and skewing effects. The general shape function contains statistical coefficients which describe the axial dispersion, skewing, and flattening of ideal monodisperse standards. A method denoted as the “method of molecular weight averages” is used to derive equations to correct GPC number- and weight-average molecular weights and intrinsic viscosities calculated from linear molecular weight calibration curves. The validity of these equations is experimentally verified with data for polystyrene, polybutadiene, and polyvinyl chloride polymers in tetrahydrofuran. The physical significance of the correction equations and their statistical coefficients is discussed in relation to the observed GPC chromatograms. Application of this shape function to the numerical Fourier analysis method for correcting differential molecular weight distribution (DMWD) curves is outlined. Also, a method is presented for obtaining corrected DMWD curves from a fitted molecular weight calibration curve corrected for instrument spreading by use of the hydrodynamic volume concept.

ISSN:0037-2366    

DOI:10.1080/00372367008068442

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The instrument spreading function suggested in Part I of this series is investigated for use with the Fourier transform method for generating corrected elution volume chromatograms. The instrument spreading parameters are obtained using linear theory on narrow molecular weight distribution standards, as indicated in Part I. The corrected chromatogram is then combined with a nonlinear molecular weight calibration curve which was fit with a function suggested by Yau and Malone to generate true values of the number- and weight-average molecular weights.

ISSN:0037-2366    

DOI:10.1080/00372367008068443

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor