Asymmetrical Flow Field Flow Fractionation - Multidetection System as a Tool for Studying Metal - Alginate Interactions

Abstract

Abstract. The present study explores the potential use of asymmetrical flow field flow fractionation (aFlFFF) with a multidetection system for the study of metal-alginate interactions. aFlFFF, coupled on-line to a differential refractive index and seven angle laser light scattering detectors was used to provide information on the alginate size distributions. In parallel, the metal distributions of metal-alginate complexes were probed by aFlFFF-high resolution inductively coupled plasma-mass spectrometry. Average values and continuous distributions of molar masses, radiuses of gyration and hydrodynamic radiuses, which are critical for understanding the role of alginates as carriers of metal pollutants, were evaluated in presence of Pb or Cd and compared with those in metal-free solutions of alginate. The values of number average and weight average molar mass, weight average radius of gyration and shape factor for alginate were 150 and 188 kg mol −1 , 53 nm and 1.7, respectively. Alginate molar mass and radius of gyration distributions were slightly shifted to higher values by the addition of micromolar concentrations of Pb or Cd. The alginate size distribution in the presence of Cd was similar to the alginate-alone control, whereas in the presence of Pb the size distribution was broader with a shift of the maximum toward higher molar masses.

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

“…Alginate molecular characteristics obtained from the aFlFFF-DRI-LS under the optimal conditions were M w = 180 kg/mol, R Gw = 50 nm, R Hw = 28 nm, PDI = 1.4, and recovery = 77%. The obtained values were in good agreement with the available literature data [31,40,41] as well as our previous work on alginate performed in the absence and presence of Pb or Cd [42].…”

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

“…Alginate-heavy metal interactions have been reported on and the authors found interesting conformational changes in the presence of metal ions (Pb 2þ and Cd 2þ ) (Alasonati, Stolpe, Benincasa, Hassellöv, & Slaveykova, 2006). In the absence of heavy metal ions, smaller molecules were found to be more elongated (r rms /r h > 2) which is what would be expected for linear polysaccharide polyelectrolyte while the average r rms /r h was 1.7.…”

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

“…Interestingly, eluted colloidal organic matter from FlFFF channel could still contain DOM with MWs smaller than the membrane nominal molecular weight cutoff (NMWCO), as shown in many previous studies, which have been attributed to electrostatic repulsion [15][16][17]34,35]. On the other hand, recoveries of DOM by FlFFF systems are generally much lower than 50% even under optimized conditions [36,26], indicating that a great proportion of DOM could be lost, most likely through the membrane during the on-channel preconcentration (sample focusing) process.…”

“…Since the thickness of the FlFFF channel is in the order of a few hundred m, the channel flow is parabolic, eluting materials distributed at different perpendicular positions http://dx.doi.org/10.1016/j.chroma.2015.04.035 0021-9673/© 2015 Elsevier B.V. All rights reserved. at different time [17]. Essentially, smaller colloids are eluted faster due to their larger diffusion coefficient and ability to diffuse further against the retention field, while larger colloids would be eluted later [18].…”