Band Broadening in Size Exclusion Chromatography of Polymers. State of the Art and Some Novel Solutions

Abstract

This work reviews the main problems of band broadening (BB) in SEC, and also presents some novel and state-of-the-art solutions. The first part of the work describes Tung's equation and presents an overview on the expected order-of-magnitude of BB effects. The second part deals with the experimental determination of the broadening function using ultra-narrow standards. The third part describes several algorithms for inverting the mass chromatograms. To allow for the simultaneous occurrence of narrow and broad regions in the same chromatogram, a novel regularization filter with a position-dependent parameter was introduced. When comparing different inversion procedures, the maximum entropy method has proven effective for recuperating structural details narrower than two times the width of the kernel. For broader and smoother regions, most other inversion procedures are equally effective. The fourth part of the work aims at producing unbiased estimates in multidetection SEC. For a derived variable obtained by linear combination of two or more chromatograms, it is preferable to directly perform the calculation from the raw measurements, and then to correct the (broadened) derived variable with the standard system kernel. When estimating molar masses from in-line molar mass sensors, intolerable errors are produced near to the baselines. To cope with this problem and to simultaneously correct for BB, a theoretical procedure is reviewed that is based on recuperating the linear (unbiased) molecular weight calibration.

Supercritical water treatment for cello-oligosaccharide production from microcrystalline cellulose

“…Caution is required in particular with the low and high molar mass tails in the distribution because those may be affected by the band-broadening effect. 23 The number-weighted average molar mass decreased nearly linearly against the reciprocal treatment time, suggesting that depolymerization occurs randomly in supercritical water. In this case the resulting polydispersity index for high polymers would be two.…”

Theory of Multiple‐Detection Size‐Exclusion Chromatography of Complex Branched Polymers

“…Baumgarten et al have given a comprehensive and critical review of the different methods used to correct band broadening. [46] Castro et al recently proposed a new method using capillary electrophoresis to obtain the true (i.e., unbroadened) MWD; [41] in the latter method, G can be any sufficiently flexible function, e.g., an exponentially modified Gaussian. Equation (11) gives the means to correct band broadening on the online viscometer signal separately.…”

“…The function G(t el , M) is however likely to be the same as the one used for mass-and number-sensitive detectors, since the band broadening in the detector cells is commonly negligible compared to band broadening before the detectors (axial dispersion in the columns, etc). [46] Band broadening can also be important after the viscometer, which is therefore always located at the end of the detectors line to overcome this problem.…”

Pulsed Laser Polymerization of Styrene in Microemulsion: Determination of Band Broadening in Size Exclusion Chromatography with Multimodal Distributions

“…Fourth, fractionation (e.g., by temperature gradient interaction chromatography [11,12] ) of polymers is regarded as a possible means to obtain monodisperse polymers which might be ideally scrutinized by MALDI-TOF. It is clear that fractionation and additional MALDI-TOF investigations add to the time need for the determination of bb and might not always be experimentally feasible in one laboratory.…”