SEC of simple polymers with molar mass detection in presence of instrumental broadening. Computer simulation study on the calculation of unbiased molecular weight distributions

Citation
Jr. Vega et Gr. Meira, SEC of simple polymers with molar mass detection in presence of instrumental broadening. Computer simulation study on the calculation of unbiased molecular weight distributions, J LIQ CHR R, 24(7), 2001, pp. 901-919
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis","Spectroscopy /Instrumentation/Analytical Sciences
Journal title
JOURNAL OF LIQUID CHROMATOGRAPHY & RELATED TECHNOLOGIES
ISSN journal
1082-6076 → ACNP
Volume
24
Issue
7
Year of publication
2001
Pages
901 - 919
Database
ISI
SICI code
1082-6076(2001)24:7<901:SOSPWM>2.0.ZU;2-5
Abstract
This theoretical work presents a correction procedure for calculating an un biased MWD when analyzing a linear homopolymer by size exclusion chromatogr aphy with molar mass detection. The fractionation and the measurements are ideal, but the chromatograms are distorted by a nonuniform and skewed instr umental broadening (IB), and are contaminated with a zero-mean random noise . The main assumption is that the molecular weight calibration is linear in the chromatogram range. The following phenomenological procedure was proposed: (i) independently co rrect the mass- and molar mass chromatograms for IB through a robust invers e filtering technique; (ii) estimate the unbiased calibration from the rati o of the corrected chromatograms; (iii) adjust a straight line to the mid-v alues of that calibration; and (iv) estimate the unbiased MWD from the line ar calibration and the corrected mass chromatogram. For the chromatogram inversions, a minimum sized broadening matrix was sele cted and a singular value decomposition technique was applied. The followin g effects were evaluated: of an increased measurement noise, of uncertainti es in the range of the measured chromatograms, and of systematic errors in the IB function. The method fails for very narrow MWDs.