Influence of ionic strength and organic modifier concentrations on characterization of aquatic fulvic and humic acids by high-performance size-exclusion chromatography

• Published in: Journal of Chromatography A 2003-10, Vol.1017 (1), p.97-105
• Main Authors: Hoque, Enamul, Wolf, Manfred, Teichmann, Günter, Peller, Ernst, Schimmack, Wolfgang, Buckau, Gunnar
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Benzopyrans - analysis; Biological and medical sciences; Chromatography, Gel - methods; Chromatography, High Pressure Liquid - methods; Ecotoxicology, biological effects of pollution; Fresh water environment; Fulvic acids; Fundamental and applied biological sciences. Psychology; Humic acids; Humic substances; Humic Substances - analysis; Ionic strength; Mobile phase composition; Molecular mass; Molecular Weight; Organic Chemicals - chemistry; Osmolar Concentration; Sensitivity and Specificity
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2003.08.038

Aquatic fulvic acid (FA) and humic acid (HA) were characterized by an aqueous high-performance size-exclusion chromatography (HPSEC) using a hydrophilic polymeric stationary phase and an aqueous eluent at neutral pH and low-ionic strength (5 mM Na 2HPO 4; final ionic strength, 13 mM). Employed HPSEC showed low sensitivity of FA to variations in ionic strength (13 and 100 mM) and contents of organic modifier (0.1 or 40% methanol) in aqueous eluent. Under these analytical conditions, peak maxima of relative UV signals versus molecular mass ( M r) defined as M p′ and peak maxima of relative mass concentrations versus M r defined as M p of FA were shown to be located at 548–690 and 500, respectively. Organic modifier concentrations of 40% methanol in aqueous eluent enabled not only analysis of FA, but also analysis of some aquatic HA by HPSEC. Analysis showed M p′ and M p values of aquatic HAs around 1000 and 600, respectively. Measured molecular mass data of FA were found to be consistent with the recently published data describing low molecular masses of FA. Results recommend the use of the described HPSEC as a simple, rapid, reproducible, low-cost method giving consistent molecular sizes/masses of FA and some aquatic HAs.