Characterize natural organic matter in typical china ’ s water using HPLC - SEC 1 with continuous wavelength UV absorbance detector

Mingquan Yan a*, , Gregory Korshin , Dongsheng Wang c 3 a Department of Environmental Engineering, Peking University, The Key Laboratory 4 of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China; 5 b Department of Civil and Environmental Engineering, University of Washington, Box 6 352700, Seattle,WA 98195-2700, United States 7 c State Key Laboratory of Environmental Aquatic Chemistry, Research Center for 8 Eco-Environmental Sciences, CAS, POB 2871, Beijing 100085, China 9 10 Abstract 11 High-performance liquid chromatography-size exclusion chromatography 12 (HPLC-SEC) coupled with continuous wavelength UV absorbance detection from 13 200 to 445 nm was used in this study to investigate molecular weight (MW) 14 distributions of natural organic matter (NOM) in a typical water in China, humic acid 15 from Yellow River. A standard humic acid, Suwannee River humic acid obtained 16 from International Humic Substances Society was used as a reference analyte. 17 Compared four fractions found by peak picking method in two-dimension 18 chromatograms: humic substances (Peak 1, at elution time 14.0-14.7 min); fulvic 19 acids or aliphatic diprotic organic acids (Peak 2, at elution time 14.7-15.2 min); low 20 MW acids (Peak 3, at elution time 15.8-16.2 min); and low MW neutrals and 21 amphiphilics, proteins and their amino acid building blocks (Peak 4, at elution time 22 16.2-17.0 min), a new fraction, lower MW humic substances (at elution time 23 15.2-15.8 min) was found in both HAs in three-dimension HPLC-SEC 24 chromatograms based on investigating the spectra at various elution time, which 25 locates between the second and third peak. Spectral parameters, such as ratio of 26