Fractionation of Natural Organic Matter by Size Exclusion Chromatography−Properties and Stability of Fractions

Abstract

An aquatic natural organic matter sample was concentrated by membrane filtration and fractionated using a size exclusion chromatography (SEC) system with a Superdex 75 column. Stability over time was investigated by reinjection of selected fractions. The reinjection yielded single peaks of a more or less Gaussian shape. From the peak shape of the individual fractions it was concluded that non-SEC mechanisms play an important role for the elution behavior. No significant change in the UV chromatograms could be detected over 5 weeks, suggesting a high stability of the fractions and only little or no alterations of the molecular weight distribution during that time period. The fractions were reexamined using a liquid chromatography system with online dissolved organic carbon detection (LCDOC system) with a TSK HW-50 (S) column. The average total recoveries of all fractions were 90 ( 4% for the Superdex system (calculated from UV-peak areas), and 102% and 105% for the spectral UV-absorbances (UVA) and dissolved organic carbon (DOC) contents measured with the LCDOC system. Peak molecular weights (M p ) were determined using polystyrene sulfonate (PSS) standards. The M p ranged from M p ) 17870 ( 113 Da to M p ) 799 ( 28 Da for the original sample and from M p ) 17998 ( 306 Da to M p ) 737 ( 30 Da for the selected fractions.

Surface-Enhanced Raman Spectroscopy of Chernozem Humic Acid and Their Fractions Obtained by Coupled Size Exclusion Chromatography—Polyacrylamide Gel Electrophoresis (SEC-PAGE)

“…Size exclusion chromatography (SEC) and electrophoresis are often used to fractionate HS due to their rapidity, sensitivity, reproducibility, and availability. [1][2][3][4][5] Recently, Trubetskoj et al 6 developed an effective method for the fractionation of soil HA based on the combination of SEC with polyacrylamide gel electrophoresis (PAGE), named SEC-PAGE. Optimal chromatographic and electrophoretic conditions were established to obtain preparative quantities of soil HA fractions, named A, B, and CþD, with different electrophoretic mobilities (EM) and molecular sizes (MS).…”

Up-scaling capillary zone electrophoresis separations of polydisperse anionic polyelectrolytes with preparative free-flow electrophoresis exemplified with a soil fulvic acid

“…The combination of FFE with TOC and pH analysis in the charge density profile allows an approach that is not possible with CZE, because TOC detectors are not possible with CE as they are with size-exclusion chromatography [28]. The FFE approach opens new possibilities for the structural investigation of humic materials: (i) Other analytical characterization techniques (chromatographic and spectroscopic such as nuclear magnetic resonance spectroscopy) can now be used to understand the changes in humic structures responsible for the mobilities within the obtained electrophoretic profile.…”

Phototransformation of riverine dissolved organic matter (DOM) in the presence of abundant iron: Effect on DOM bioavailability

“…We used gel permeation chromatography (TSKHW50S) with UV absorbance (at 254 nm) and DOC detection to characterize the apparent molecular weight distribution of the DOM fractions before and after irradiation (Mueller et al 2000). The detection of DOC was based on the absorption of infrared light by CO 2 from photo-oxidized DOC.…”