Kaitlin C. Lesco , Stefanie Van Wychen , Arnav Deshpande , Lieve M.L. Laurens , S. Kim Ratanathanawongs Williams
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引用次数: 0
Abstract
A multifaceted separations platform that incorporates the strengths of asymmetrical flow field-flow fractionation with multi-detectors (AF4-MD), high performance anion exchange chromatography (HPAEC), and hydrophilic interaction liquid chromatography with mass spectrometry (HILIC-MS) is developed to obtain a more complete picture of the molecular weights (MW), composition, and salt-induced aggregation behavior of extracellular polymeric substances (EPS) produced by the algae Chlorella vulgaris. The absence of a stationary phase makes AF4-MD particularly well suited for characterizing polydisperse hydrocolloid polymers as well as studies that investigate the effect of ionic environments that aligns with the natural environment of C. vulgaris. Fractionation of C. vulgaris EPS revealed three distinct MW populations ranging from 4 × 10⁴ to 3 × 10⁸ Daltons. This exceeds the previously reported MW by three orders of magnitude and reports a previously unknown size subpopulation. The optimized AF4-MD technique was then used to produce two size fractions that were probed using HPAEC and LC-MS. These orthogonal methods uncovered compositional heterogeneity across fractions, with variations in monosaccharides and amino acids.
AF4-MD is also well suited for studying the behavior of EPS in the presence of different salts. For each salt studied, e.g., NaNO3, NaCl, and MgCl2, an increase in solution ionic strength results in aggregation as corroborated by a shift to higher MWs. Each salt exhibited distinct effects on EPS aggregation, with NaCl causing the least aggregation and MgCl2 the most. These findings highlight the need for multiple techniques when analyzing complex polymers such as EPS and the benefits of AF4-MD in elucidating complex polymer behaviors in different ionic environments.
期刊介绍:
The Journal of Chromatography A provides a forum for the publication of original research and critical reviews on all aspects of fundamental and applied separation science. The scope of the journal includes chromatography and related techniques, electromigration techniques (e.g. electrophoresis, electrochromatography), hyphenated and other multi-dimensional techniques, sample preparation, and detection methods such as mass spectrometry. Contributions consist mainly of research papers dealing with the theory of separation methods, instrumental developments and analytical and preparative applications of general interest.