title: Characterization of dissolved organic matter using high-performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) with a multiple wavelength absorbance detector.
abstract: High-performance liquid chromatography-size exclusion chromatography (HPLC-SEC) coupled with a multiple wavelength absorbance detector (200-445 nm) was used in this study to investigate the apparent molecular weight (AMW) distributions of dissolved organic matter (DOM). Standard DOM, namely humic acid, fulvic acid and hydrophilic acid, from the Suwannee River were tested to ascertain the performance and sensitivity of the method. In addition to four compounds groups: humic substances (Peak 1, AMW 16 kD), fulvic acids (Peak 2, AMW 11 kD), low AMW acids (Peak 3, AMW 5 kD), and low AMW neutral and amphiphilic molecules, proteins and their amino acid building blocks (Peak 4, AMW 3 kD), an new group that appears to include low AMW, 6-10 kD, humic substances was found based on investigating the spectra at various elution times. The spectroscopic parameter S(>365) (slope at wavelengths >365 nm) was determined to be a good predictor of the AMW of the DOM. The detector wavelength played an important role in evaluating the AMW distribution. For some fractions, such as the humic and low AMW non-aromatic substances, the error in measurement was ± 30% as determined by two-dimensional chromatograms detected at an artificially selected wavelength. HPLC-SEC with multiple wavelength absorbance detection was found to be a useful technique for DOM characterization. It characterized the AMW distributions of DOM more accurately and provided additional, potentially important information concerning the properties of DOM with varying AMWs.
authors.affiliation: Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China. yanmq@pku.edu.cn
authors.forename: Mingquan
authors.initials: M
authors.lastname: Yan
authors.forename: Gregory
authors.initials: G
authors.lastname: Korshin
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Wang
authors.forename: Zhenxiao
authors.initials: Z
authors.lastname: Cai
mesh_terms: D000042:Absorption; D001578:Benzopyrans / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D002850:Chromatography, Gel / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006812:Humic Substances / Q000032:analysis; D057927:Hydrophobic and Hydrophilic Interactions; D008970:Molecular Weight; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry* / Q000302:isolation & purification; D045483:Rivers / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001578:Benzopyrans; D006812:Humic Substances; D009930:Organic Chemicals; C005023:fulvic acid