Isolation and characterization of Chinese standard fulvic acid sub-fractions separated from forest soil by stepwise elution with pyrophosphate buffer.
XAD-8 adsorption technique coupled with stepwise elution using pyrophosphate buffers with initial pH values of 3, 5, 7, 9, and 13 was developed to isolate Chinese standard fulvic acid (FA) and then separated the FA into five sub-fractions: FApH3, FApH5, FApH7, FApH9 and FApH13, respectively. Mass percentages of FApH3-FApH13 decreased from 42% to 2.5%, and the recovery ratios ranged from 99.0% to 99.5%. Earlier eluting sub-fractions contained greater proportions of carboxylic groups with greater polarity and molecular mass, and later eluting sub-fractions had greater phenolic and aliphatic content. Protein-like components, as well as amorphous and crystalline poly(methylene)-containing components were enriched using neutral and basic buffers. Three main mechanisms likely affect stepwise elution of humic components from XAD-8 resin with pyrophosphate buffers including: 1) the carboxylic-rich sub-fractions are deprotonated at lower pH values and eluted earlier, while phenolic-rich sub-fractions are deprotonated at greater pH values and eluted later. 2) protein or protein-like components can be desorbed and eluted by use of stepwise elution as progressively greater pH values exceed their isoelectric points. 3) size exclusion affects elution of FA sub-fractions. Successful isolation of FA sub-fractions will benefit exploration of the origin, structure, evolution and the investigation of interactions with environmental contaminants.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Yingchen
Y
Bai
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Fengchang
F
Wu
Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, USA.
Baoshan
B
Xing
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Wei
W
Meng
Lanzhou New Area Environmental Protection Bureau, Lanzhou, 730314, China.
Guolan
G
Shi
Research Center of Environmental Biology and Green Chemistry, School of Environmental and Municipal Engineering, Qingdao Technological University, Qingdao, 266033, China.
Yan
Y
Ma
1] Department of Biomedical and Veterinary Biosciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada [2] Department of Biology and Chemistry, and State Key Laboratory for Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China [3] State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210046, China [4] Zoology Department, National Food Safety and Toxicology Center, and Center for Integrative Toxicology, Michigan State University, East Lansing, 48824, USA.
John P
JP
Giesy
D000180:Acrylic Resins / Q000737:chemistry; D000327:Adsorption; D001578:Benzopyrans / Q000737:chemistry* / Q000302:isolation & purification*; D002021:Buffers; D005591:Chemical Fractionation / Q000379:methods; D002681:China; D011756:Diphosphates / Q000737:chemistry*; D065928:Forests; D006863:Hydrogen-Ion Concentration; D007475:Ion Exchange Resins / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011137:Polystyrenes / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared
D000180:Acrylic Resins; D001578:Benzopyrans; D002021:Buffers; D011756:Diphosphates; D007475:Ion Exchange Resins; D011137:Polystyrenes; D012987:Soil; C107241:diphosphoric acid; C005023:fulvic acid