title: An improved method for the extraction of low molecular weight organic acids in variable charge soils.
abstract: Due to specific adsorption to variable charge soils, low molecular weight organic acids (LMWOAs) have not been sufficiently extracted, even if common extractants, such as water and 0.1 M sodium hydroxide (NaOH), were employed. In this work, the method for extracting LMWOAs in soils with 0.1 M NaOH was improved for variable charge soils; e.g. 1.0 M potassium fluoride (KF) with pH 4.0 was applied as an extractant jointed with 0.1 M NaOH based on its stronger ability to change the electrochemical properties of variable charge soils by specific adsorption. With the proposed method, the recoveries of oxalic, tartaric, malic, citric and fumaric acids were increased from 83 +/- 4, 93 +/- 1, 22 +/- 2, 63 +/- 5 and 84 +/- 3% to 98 +/- 2, 100 +/- 2, 85 +/- 2, 90 +/- 2 and 89 +/- 2%, respectively, compared with NaOH alone. Simultaneously, the LMWOAs in Agri-Udic Ferrosol with field moisture were measured with a satisfactory result.
authors.affiliation: Institute of Soil Science, Chinese Academy of Sciences, China.
authors.forename: Xingxiang
authors.initials: X
authors.lastname: Wang
authors.forename: Qingman
authors.initials: Q
authors.lastname: Li
authors.forename: Jianhua
authors.initials: J
authors.lastname: Ding
authors.forename: Mingbiao
authors.initials: M
authors.lastname: Luo
authors.forename: Taolin
authors.initials: T
authors.lastname: Zhang
authors.forename: Yiyong
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D000143:Acids / Q000737:chemistry* / Q000302:isolation & purification*; D019343:Citric Acid / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D005459:Fluorides / Q000737:chemistry; D005650:Fumarates / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry; D008293:Malates / Q000737:chemistry; D008970:Molecular Weight; D009930:Organic Chemicals / Q000737:chemistry* / Q000302:isolation & purification*; D019815:Oxalic Acid / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000737:chemistry; D013644:Tartrates / Q000737:chemistry; D013997:Time Factors
chemical_list: D000143:Acids; D005650:Fumarates; D008293:Malates; D009930:Organic Chemicals; D017680:Potassium Compounds; D012987:Soil; D012989:Soil Pollutants; D013644:Tartrates; D019343:Citric Acid; D019344:Lactic Acid; C030298:malic acid; C032005:fumaric acid; C033320:potassium fluoride; D019815:Oxalic Acid; D005459:Fluorides; C029768:tartaric acid