Asymmetrical flow field‐flow fractionation coupled to multiangle laser light scattering detector: Optimization of crossflow rate, carrier characteristics, and injected mass in alginate separation

Abstract

The coupling of the flow field-flow fractionation (FlFFF) to differential refractive index (DRI) and multiangle laser light scattering (LS) detectors is a powerful tool for characterizing charged polysaccharides such as alginate. However, the correct interpretation of the experimental results and extrapolation of meaningful molecular parameters by using an analytical tool with such a level of complexity requires improvement of the knowledge of the alginate behavior in the channel and careful optimization of the operating conditions. Therefore, the influence of the critical operating parameters, such as crossflow rate, carrier composition and concentration, and sample load, on the alginate retention was carefully evaluated. Combined information obtained simultaneously by DRI and LS detectors over the wide range of the crossflow rate, carrier liquid concentration, and injected amount, allowed to set the appropriate combination of optimal parameters. It was found that the crossflow rate of 0.25 mL/min, carrier solution containing 5x10(-2 )mol/L ammonium or sodium chloride, and 50-100 microg of injected sample mass were necessary to achieve complete separation and determination of the meaningful molecular characteristics. The values of the weight-average hydrodynamic radius (R(Hw)), radius of gyration (R(G)), and molar mass (M), obtained under the optimal conditions were in good agreement to those found for alginates in the literature.

A critical evaluation of an asymmetrical flow field-flow fractionation system for colloidal size characterization of natural organic matter

“…Therefore, when the carrier solution was changed from Carrier 1 to 2, pH increased from 6 to 8, leading to higher recovery and earlier elution. In addition, it has been shown that lower ionic strength would result in an increase in the electric double layer of colloids and lead to the positioning of colloids further away from the membrane [53,50,54]. Thus, this electrostatic influence may cause shorter retention time and higher recovery [36].…”

Separation and characterization of food macromolecules using field-flow fractionation: A review

“…The monomers can appear in different sequences or blocks. The difficulties in analyzing alginate, due to their charged character, have been reported on in literature (Alasonati, Benincasa, & Slaveykova, 2007). Further complications may arise due to alginates, sometimes, strong viscosity enhancing effects and in a comparative study between SEC and AF4, analysis of polymers with M > 10 5 g/mol was only possible with the latter (Storz et al, 2009).…”

Exopolysaccharides produced by bacteria isolated from the pelagic Southern Ocean — Role in Fe binding, chemical reactivity, and bioavailability

“…Focusing and elution conditions were previously optimized by using a model EPS such as alginate (Alasonati et al, 2006(Alasonati et al, , 2007. The optimal focusing conditions used here were: focusing time t foc equal to 14 min; inlet flow rate, V in , 0.09 mL min −1 ; focus flow rate, V foc , 5 mL min −1 ; crossflow rate, V c , 4.09 mL min −1 , outlet flow rate, V out , 1 mL min −1 .…”