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This review is a continuation of Part IX (1), in which the theory of light scattering is given, including pertinent equations and data analysis. The following contribution is a summary [...]

Light scattering detectors are ideally suited for size-exclusion chromatography (SEC) because they provide the molecular weight and radius of gyration information of polymeric samples without column calibration. In this article, [...]

All analytical techniques are governed by the principles of physical chemistry, and chromatography is certainly no exception. By examining the underlying concepts of size exclusion chromatography (SEC), students can gain greater appreciation of and insight into the science and utility of thermodynamics, as well as solution properties of macromolecules. In this paper we will show how the separation mechanism that governs SEC, an unusual form of chromatography, can be explained using the tenets of thermodynamics. This paper gives educators access to an HPLC technique usually not included in undergraduate chemistry curriculum.

From a practical point of view, just glancing at a chromatogram can often reveal whether or not a separation has been achieved by noting the depth of the valley between peaks of interest, or if there are hints of partially resolved components. The effectiveness of a separation, however, can be quantified by measuring the resolution, a commonly used parameter found in many disciplines. This review offers insight into the meaning and significance of chromatographic resolution, and factors that influence it. Also presented is the equation for predicting the required number of theoretical plates to obtain a given resolution., Our goal as chromatographers is to develop methods that have sufficient resolution to separate components of interest, for both qualitative and quantitative analyses. To increase resolution, we must either increase [...]

The purpose of this tutorial is to present equations for estimating the extent of broadening that a solute undergoes as it migrates through a chromatographic column in high performance liquid [...]

Plates are generated during the elution of solutes through a chromatographic column and contain a wealth of information about the separation process, mainly peak dispersion. It is an easily measured [...]

The previous articles in this series on Chromatography Fundamentals described thermodynamics of separations (1,2) and chromatographic retention (3), as applied to liquid chromatography (LC). This article presents the origin of [...]

From our previous discussion on thermodynamics of liquid chromatography (LC), we showed that retention, and thus separation, depends upon the distribution of solutes between mobile and stationary phases during migration [...]

In Part I, we established that chromatographic separations are governed by the distribution coefficient of solutes when they partition between mobile and stationary phases (1). The energetics of this process, [...]

Professor Barry L. Karger, one of the earliest contributors of modern high performance liquid chromatography (HPLC) and bioanalytical separations and analysis, recently celebrated his 50th year as professor of chemistry [...]

Size-exclusion chromatography (SEC) is a well-established high performance liquid chromatography (HPLC) method for separating macromolecules according to their hydrodynamic volume. When SEC was first recognized 60 years ago by biochemists [...]

This month's installment surveys traditional and modern approaches for extracting and determining additives, contaminants, and low-molecular-weight components that may be present in synthetic polymers or polymeric materials. After sample workup, [...]

For this month's installment, guest authors Barth and Saunders discuss the present state of size-exclusion chromatography (SEC) columns for the separation of synthetic polymers and biopolymers. A comprehensive review of [...]

In the practice of size-exclusion chromatography (SEC), the suggested arrangement of columns with different pore sizes appears to be contradictory. Although most column manufacturers recommend that the large-pore-size column be placed first in a set, for example connected to the injector, followed by columns with progressively larger pores, other workers in the field suggest the reverse. In view of these conflicting practices, a study was conducted to determine the influence of column arrangement on molecular size separation and peak broadening using a high-precision SEC chromatographic system and a two-column set with exclusion molecular weight limits of 2 x [10.sup.3] and 2 x [10.sup.6] g/mol. As would be expected, SEC column order was found to have no effect on peak resolution, column efficiency, calibration curve fit, or measured molecular weights on a series of polystyrene standards and poly(tetramethylene ether glycol) samples. These results suggest that any column order can be employed provided that the direction of flow through each column established by manufacturer is used and that the minimum length of low-dead-volume capillary tubing is used for column coupling., Although size-exclusion chromatography (SEC) is a well-estabished technique used by most laboratories involved with macromolecule characterization, there is still disagreement about which pore-size column to place first when using a [...]

Although size exclusion chromatography (SEC) is a fairly mature separation technique, improvements are continually made in packing technology. Howard Barth and Greg Saunders review some of the basics of SEC [...]

A review of published literature on liquid chromatography for the period Oct 1995 to Oct 1997 is presented. The papers covered topics on peak purity, deconvolution, solute retention, mobile-phase studies, capillary electrochromatography, support activation and affinity ligand immobilization. Papers on stationary-phase studies, ion chromatography, ion pairing, optical isomers and postcolumn derivatization were also included in the review.

A review of published literature on size exclusion chromatography and polymer separation techniques abstracted by Chemical Abstracts and Medline for the period 1996 to 1997 is presented. The papers covered topics on band broadening, calibration, automation and quality control, mobile phases, detectors and non-size exclusion effects. Papers on temperature-rising elution fractionation, sample cleanup and lignins were also included in the review.

A fundamental review of liquid chromatography literature addresses major changes for the time period of Oct. 1993 to Oct. 1995. Most publications are gathered from on-line CAS database with additions from personal data gathering by the reviewers. The subject matter is generally treated in Scott's Liquid Chromatography for the Analyst, Riley's Pharmaceutical and Biomedical Applications of Liquid Chromatography, and Subramanian's Process Scale Liquid Chromatography.

A review of literature of size exclusion chromatography, and of high performance liquid chromatography of polymers, covers papers published during the time period of 1994 to 1995. Articles on significant advances in the subject are sourced from Chemical Abstracts and Medline. Reviews of specific topics cover theory, band broadening, calibration, detectors, packings, compositional heterogeneity, physiochemicaal studies, columns and applications.

A review of literature on particle size analysis published in Chemical Abstracts from 1993, volume 118 to 1994 volume 1212 is presented. Aerosol and atmospheric measurements and industrial-scale particle fractionationstudies were generally omitted. References on macromolecules, micelles and related structures are also included.

A review of selected literature on the chemistry of the separation process in liquid chromatography (LC), published during Dec. 1991-Dec. 1993, is presented. The review covers research and application papers involving normal-phase LC, reversed-phase LC, biopolymer separations, affinity chromatography, ion chromatography, secondary chemical equilibria, microcolumn and opentubular LC, trace analysis and preparative LC.

A review of selected literature on size exclusion chromatography (SEC) and the adsorption, precipitation and critical chromatography (HPLC) of polymers published during 1992-1993 shows considerable increase in the use of on-line light-scattering detectors and viscometers. Topics included in the review include brand broadening, calibration, detectors, packings, compositional heterogeneity, microcolumn SEC and preparative SEC.

Analytical techniques that have been applied for the definition of a particle are reviewed. This involves the utilization of scattering techniques, size exclusion/hydrodynamic chromatography, field-flow fractionation electrozone sensing, sedimentation/centrifugation, sieving and other methods such as ultrasonics. An intercomparison of the techniques in terms of particle shape and particle size standards is also provided.

Developments in the field of size exclusion chromatography (SEC) from 1989 to 1991 mainly focused on the expansion of its applications. Innovations in calibration, detection and chromatographic designs were also mentioned in a number of scientific publications. Attempts were made to characterize compounds such as amphipathic biopolymers and highly hydrophobic and ionic groups which were slightly inaccessible to SEC analysis. The introduction of new columns and mobile phases in several experiments enhanced the separation efficiency of the technique.

Many scientific papers written between Dec 1989, and Dec 1991, indicated that the application of various theoretical and procedural concepts aimed to improve the efficiency and selectivity of liquid chromatography were proven to be successful. New materials and methodologies were tested on the different types of liquid chromatography. The improvements in the technique's performance made it useful and valuable in a number of compounds and analytical experiments.