Continuous Viscometric Detection in Size Exclusion Chromatography

Abstract

Continuous viscometric, detection is based on the measurement of ressure drop in an on-line small capillary tube in which cErornatogra hic eluents flow at constant flow rate. This detector is ayways coupled with a concentration detector (usually refractometer) and located before it t o avoid back presrura in the refractometer. In order to obtain reliable information f o r polymer samples, it is general1 necessary to connect these two detectors to a computer whicx performs data acquisition and treatment.First we discuss the rroblem of shape, g?ometry and dimensions of the viscometer. Tge typical charactsristlcs are the result of a comproaise between contradictory hrgets, mainly small internal vblume !ow shear rate,and low prassure drop. It is shown that $oiseullle's lammar flow is only obtained when coiling radius of the measurement tube ? s greater than 6 cm which is not the cass inside tne refractometer. Accbrdingly, tiro pressura transducers are necessary t o eliminate pressure drop data comlng from refractorneter. LESEC, LECACHEUX, AND MAROTIn a second ,part, we show how to extract information from pressure variation data. By using conc?ntration data, pure solvent pressure and sample pressure it 1s possibl? to calculate intrinsic viscosity extrapolated to zsro concentration at,each,point of the chromato ram. By comparison rith intrinsic viscosity cf the pol mar use! for calibration, a correction of hydro& narcic v01une according : ? Benoit's universal calibration leads t o absolute aolecuiar welghts.In addition, for a linear polymor the knowled3~ of log [ q J versus log H leads to the determination of .'arkHouwin$ relationship coafficients. For branched polyaers. viscosity laws are curved aild the comparison betweer. the linear lar,corresponding to the linear equiyalent pol iiisr an$ the experimental law allows the daterminat:on ofl'the $ branching pirameter distribution.

Estimation of Hydrodynamic Volume of Proteins Using High-Performance Size-Exclusion Chromatography and Intrinsic Viscosity Measurement: An Attempt At Universal Calibration

“…There are several articles (23)(24)(25)(40)(41)(42)(43) on the validity of the universal calibration procedure for watersoluble polymers, however, there are few articles (37-39) that for proteins because of the lack of polymer standards having a narrow molecular weight distribution with a silica-basd column.…”

Degradation of High Molecular Weight Polystyrenes During the SEC Separation Process, as Demonstrated by SEC Coupled with Lalls and by Static Light Scattering

“…4~1 0~ using the set of columns E ( * Columns E without a pre-column filter degradation might be expected for polymers with very high MW. 20 Actually, when we used SEC coupled with the additional third detector (CVM), the degradation degrees of PS 8 . 4~1 0~ and PS 1 .…”

Correlation between molecular structure and copolymer composition and the Mark-Houwink constants of methyl methacrylate/N-phenylmaleimide copolymers

“…In modern gel permeation chromatography, on-line continuous viscosimetry, first described by Ouano 1) and based on the continuous measurement of the eluent pressure drop through a capillary tube, is convenient 1,2) . Using a system such as the Waters 150 CV, excellent results for K and a values of the MarkHouwink relation [g] = K N M a (1) for homopolymers can be obtained [3][4][5] .…”