Project Details:
Data Treatment in SEC and Other Techniques of Polymer Characterization. Correction for Band Broadening and Other Sources of Error
| Project No.: | 2009-019-2-400 |
| Start date: | 2010-02-01 |
| End date: | 0000-00-00 |
| Division: | Polymer Division |
The project aims at improving polymer characterization through standardization of the data treatment and experimental conditions employed in Size Exclusion Chromatography (SEC) and other LC techniques. The eventual IUPAC recommendations should be useful not only for the general chromatographer, but also for the manufacturer of instruments and columns.
Size Exclusion Chromatography (SEC) is the main analytical technique for determining the molar mass distribution (MMD) of polymers. In spite of its ample use, its accuracy is relatively low, as is verified by the scatter of results obtained in round-robin tests. For accurate results, not only adequate chromatographic equipment is necessary, but also required are a careful experimental work and a judicious data treatment of the raw data.
Band broadening (BB) can importantly affect the estimates of narrow or multimodal MMDs; and only a few commercial software corrects for the biases MMD averages. However, none of the manufacturers of columns or standards offer any practical estimation of the BB function nor well described correction software for estimating the unbiased MMD. Apart from BB, other sources of error can also greatly affect the MMD estimates; e.g.: polymer degradation, column saturation (at high M’s), low sensitivity of “molar mass†sensors to low M, chromatogram baseline selection, nonlinearities of the detector response, errors associated with signal ratios, errors in the interdetector volume, swelling/ unswelling of the gel, etc.
The present project is a continuation of Project 2003-023-2-400 G.Meira (IUPAC) entitled: “Data Treatment in Size Exclusion Chromatography of Polymersâ€. The main outcome of the previous project was the article: “Band Broadening Function in Size Exclusion Chromatography of Polymers: Review of Some Recent Developmentsâ€, by G.R. Meira, M. NetopilÃk, M. Potschka, I. Schnöll-Bitai, J. Vega (2007), Macromol. Symp. 2007, 258, 186–197.
The proposed work will be tentatively subdivided into the sublines that follow.
1. Effect of the injected polymer mass on the peak elution times of narrow standards and on the derived molar mass calibration.
2. Triple-detection SEC: direct estimation of an unbiased MMD of narrow standards without explicit calculation of the BBF.
3. Propagation of errors into the Distribution of Long Chain Branches, as determined by SEC/ Visc. or SEC/ LS.
4. Quantitative determination of the MMD and other distributions in chromatographically-complex polymers (e.g.: polymer mixtures and copolymers).
5. Evaluation of theoretical models for LC of polymers, and their eventual use for improving polymer characterization.
6. Procedures for robust baseline identification.
7. Swelling/ unswelling of the gel.
8. Compensation of the dependence of detector response on molar mass.
9. Study of preferential solvation.
10. Promotion of the recommended data treatment through simulation programs and other media, in the context of education of chromatographers.
The final project outcome will be a round-up paper co-authored by most of the project participants. The paper will review the main developments and it will hopefully include practical recommendations for improving the accuracy of polymer measurements. The recommendations will be aimed at the normal chromatographer, and/or at the manufacturer of LC equipment, columns, and software. The review could include a critical evaluation of numerical procedures, with comments on accuracy and precision, ease of implementation, and prerequisites of applicability.
The first Project Meeting is planned to take place in Rome between Sept. 6 to 10, 2010, at the 16th International Symposium on Separation Sciences (16th ISSS, http://www.16isssrome2010.it). The following participants are willing to assist to the Rome Symposium: G. Meira, D. Berek, T. Chang, F. Dondi, A. Felinger, J. Reijenga, and B. Trathnigg.