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Title: An SEC/MALS Study of Alternan Degradation During Size-exclusion Chromatographic Analysis

item STRIEGEL, ANDRE - Florida State University
item ISENBERG, SAMANTHA - Florida State University
item Cote, Gregory

Submitted to: Analytical and Bioanalytical Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2009
Publication Date: 6/25/2009
Citation: Striegel, A.M., Isenberg, S.L., Cote, G.L. 2009. An SEC/MALS study of alternan degradation during size-exclusion chromatographic analysis. Analytical and Bioanalytical Chemistry. 394:1887-1893.

Interpretive Summary: This research provides new information that will allow more accurate size determination of very large chains of connected molecules known as polymers. Polymers are common in nature and have many food and agriculture applications, but can be difficult to accurately quantify in size due to the lack of reproducibility between different sizing methods. This study shows that these polymers may break apart using some laboratory measuring techniques, giving falsely low size values, and provides improved methods that circumvent this problem. This work will allow scientists to more accurately estimate the size of these very large molecules, resulting in improved product development and application.

Technical Abstract: The degradation of high molar mass polymers during size-exclusion chromatography (SEC) analysis has been a topic of interest for several decades. Should a polymer degrade during analysis, the accuracy of the molar mass (M) and architectural information obtained will be compromised. To this effect, a number of studies have provided extensive qualitative circumstantial evidence of the degradation of ultra-high molar mass polymers in SEC columns. The evidence generally given is a change in the elution profile of the analyte toward larger elution volumes as a function of increasing flow rate, elution volume in SEC being inversely proportional to analyte size in solution. Not only is very little understood about the types of flow fields involved in the degradation, but there is even doubt about whether degradation is even occurring. In many cases, the latter might instead be an unrecognized manifestation of slalom chromatography occurring within the SEC column. Here, using SEC coupled to both static multi-angle light scattering and differential refractometry detectors, we show unambiguous evidence of the degradation of the ultra-high-M polysaccharide alternan.