A 3 Overlapped Peaks in Size Exclusion Chromatography of Complex Polysaccharides

High-performance size exclusion (HPSE) chromatography, also known as gel permeation chromatography, is a major tool for the estimation of molecular weights of polymers, proteins, and other macromolecules. Fish-man and coworkers [4-6] showed that the HPSE peaks of polysaccharides such as pectins, gums, and starches give good fits to the Gaussian peak shape. Both concentration-sensitive and viscosity detectors are used. The analytical system consists of up to three gel permeation columns in tandem and is subjected to universal calibration with macromolecular standards of

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Figure 14.6 HPSE chromatograms for common maize analyzed by a multiple Gaussian model. The solid lines represent experimental data and the dotted lines are computed for the best fit to the model. Response curves for viscosity (top) and refractive index detectors (bottom) are shown. Underlying curves show resolved components. (Reprinted with permission from [6], copyright by Elsevier.)

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Figure 14.6 HPSE chromatograms for common maize analyzed by a multiple Gaussian model. The solid lines represent experimental data and the dotted lines are computed for the best fit to the model. Response curves for viscosity (top) and refractive index detectors (bottom) are shown. Underlying curves show resolved components. (Reprinted with permission from [6], copyright by Elsevier.)

known molecular weights. These standards were found to give good fits to Gaussian peak shapes. Global values of the intrinsic viscosity, radius of gyration, and weight-average molecular weights of the components can be extracted from the properties of resolved components.

Some examples of this type of analysis for starch from common maize (Figure 14.6) and for gum locust bean (Figure 14.7) show the severely overlapped nature of the HPSE chromatograms typical of complex polysaccharide samples. The overlapped Gaussian model for the analysis of these data is the same as that in Chapter 7. It is clear that without the peak resolution analysis, few results of a quantitative nature would be available for these samples.

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Figure 14.7 HPSE chromatograms for gum locust beans analyzed by a multiple Gaussian model. The solid lines represents experimental data and the dotted lines are computed for the best fit to the model. Response curves for viscosity (a) and refractive index detectors (b) are shown. Underlying curves show resolved components. (Reprinted with permission from [5], copyright by the American Chemical Society.)

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Figure 14.7 HPSE chromatograms for gum locust beans analyzed by a multiple Gaussian model. The solid lines represents experimental data and the dotted lines are computed for the best fit to the model. Response curves for viscosity (a) and refractive index detectors (b) are shown. Underlying curves show resolved components. (Reprinted with permission from [5], copyright by the American Chemical Society.)

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