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Molar Mass Distribution and Size of Hydroxyethyl Starch Fractions Obtained by Continuous Polymer Fractionation
Author(s) -
Gosch Carola I.,
Haase Tanja,
Wolf Bernhard A.,
Kulicke WernerMichael
Publication year - 2002
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/1521-379x(200209)54:9<375::aid-star2222375>3.0.co;2-g
Subject(s) - molar mass , fractionation , molar mass distribution , radius of gyration , chemistry , size exclusion chromatography , amylopectin , analytical chemistry (journal) , chromatography , molar , polymer , molar concentration , gel permeation chromatography , starch , amylose , organic chemistry , geology , paleontology , enzyme
Abstract By the use of continuous polymer fractionation (CPF) the initial polymer can be separated into fractions of different molar masses, which makes it possible to obtain hydroxyethyl starch (HES) fractions tailor‐made for specific application. Two samples of HES (HES A and HES B) were fractionated by means of CPF. By size‐exclusion chromatography‐multi‐angle laser light‐scattering‐differential refractive index (SEC/ MALLS/DRI) measurements it was shown that CPF is able to remove the low‐molarmass components and to adjust the samples to various desired molar masses with lower polydispersities than the original samples. In terms of the weight‐average mean molar mass M W , the sol fractions have smaller molar masses than the starting sample, whilst the gel fractions have higher molar masses. Furthermore the radius of gyration R G could be determined for the initial sample HES B with 19.7 and 19.4 nm and also for some of its fractions. However, no general R G —M W relationship could be established for the HES samples fractionated using CPF. This is probably due to the complex branched structure of amylopectin. M W and M W /M n of the six fractions obtained from HES A with M W = 161, 000 g/mol and M W /M n = 4.7 ranged from 19, 000 to 362, 000 g/mol with M W /M n from 1.8 to 3.1. The molar masses of the four fractions obtained from HES B with M W = 460, 000 g/mol and M W /M n = 6.0 were between 18, 000 and 680, 000 g/mol with M W /M n from 1.7 to 4.8 or between 202, 000 and 1, 005, 000 g/mol with M W /M n from 2.7 to 4.7 depending on fractionation strategy.