Capillary electrophoretic separation of humic substances using hydroxyethyl cellulose as a buffer additive and its application to characterization of humic substances in a river water sample

Abstract

We have developed a concise tool for the investigation of the transition of humic substances in environmental water. The separation of water-soluble humic substances was achieved rapidly and effectively by capillary electrophoresis using a polyacrylamide-coated capillary and a phosphate electrophoretic buffer solution (pH 7.0) containing hydroxyethyl cellulose. The separation mechanism was assessed using the ultrafiltration technique. The effect of the complexation of humic substances with metal ions was studied by using the proposed method. When Fe(III) ions or EDTA was added to the sample solution of fulvic acid, a distinct change in the electropherogram pattern based on the conformational change of fulvic acid was observed. The successful application of the proposed method to the characterization of humic substances in a river water sample was also demonstrated.

Dynamic Coating Capillary Electrophoresis for Separation of Humic Acid Using Mixture Solution of Non-ionic Polymers both as Coating Agent and Separation Medium

“…12 Of course, the proposed method would be applicable for the investigation of interactions of humic substances with coexisting materials including metal ions. The separation performance on the separation of 0.1 -2 kbp of DNA ladder by the proposed method showed that separation by the proposed method basically undergoes the molecular sieving effect of the mixed-polymer medium and that the proposed method was also applicable for the separation of analytes other than humic substances.…”

“…12 On the other hand, it was found that the addition of PEG 10000 to the electrophoretic buffer solution slightly improved CE resolution. 20 An electrophoretic buffer solution containing both HEC and PEG 10000 was, therefore, tested as the first candidate for the solution that served as both the separation medium and the dynamic coating agent in this study.…”

“…10,11 We previously reported a powerful CE separation technique for humic substances using a polyacrylamide-coated capillary and an electrophoretic buffer solution containing hydroxyethyl cellulose (HEC). 12 In the method, electroosmotic flow (EOF) must be eliminated by immobilizing polyacrylamide on the capillary inner wall via silane coupling treatment followed by in-capillary polymerization 13 to avoid the delay of separation time since humic substances are polyanions with large electrophoretic mobility against the direction of EOF. Though the separation performance of the method is excellent, the procedure for preparing the polyacrylamide-coated capillary is troublesome.…”

Natural Organic Matter in Ecosystems - a Review

“…Additionally different electrophoregram profiles and migration times of humic and fulvic acids have been used to distinguish between young, old, autochthonous and allochthonous natural organic matter. Sometimes, especially isotachophoresis is used to isolation of humic substances fractions (TAKAHASHI et al, 2009, NAGYOVA et al, 2001.…”