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Quantification of long‐chain fatty acids in dissolved organic matter and soils
Author(s) -
Jandl Gerald,
Schulten HansRolf,
Leinweber Peter
Publication year - 2002
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/1522-2624(200204)165:2<133::aid-jpln133>3.0.co;2-t
Subject(s) - chemistry , tetramethylammonium hydroxide , dissolved organic carbon , fatty acid , environmental chemistry , chromatography , soil water , organic matter , alkyl , organic chemistry , environmental science , soil science
The objective was to develop and adapt a versatile analytical method for the quantification of solvent extractable, saturated long‐chain fatty acids in aquatic and terrestrial environments. Fulvic (FA) and humic (HA) acids, dissolved organic matter (DOM) in water, as well as organic matter in whole soils (SOM) of different horizons were investigated. The proposed methodology comprised extraction by dichloromethane/acetone and derivatization with tetramethylammonium hydroxide (TMAH) followed by gas chromatography/mass spectrometry (GC/MS) and library searches. The C 10:0 to C 34:0 methyl esters of n ‐alkyl fatty acids were used as external standards for calibration. The total concentrations of C 14:0 to C 28:0 n ‐alkyl fatty acids were determined in DOM obtained by reverse‐osmosis of Suwannee river water (309.3 μg g —1 ), in freeze‐dried brown lake water (180.6 μg g —1 ), its DOM concentrate (93.0 μg g —1 ), humic acid (43.1 μg g —1 ), and fulvic acid (42.5 μg g —1 ). The concentrations of the methylated fatty acids ( n ‐C 16:0 to n ‐C 28:0 ) were significantly ( r 2 = 0.9999) correlated with the proportions of marker signals (% total ion intensity (TII), m/z 256 to m/z 508) in the corresponding pyrolysis‐field ionization (FI) mass spectra. The concentrations of terrestrial C 10:0 to C 34:0 n ‐alkyl fatty acids from four soil samples ranged from 0.02 μg g —1 to 11 μg g —1 . The total concentrations of the extractable fatty acids were quantified from a Podzol Bh horizon (26.2 μg g —1 ), Phaeozem Ap unfertilized (48.1 μg g —1 ), Phaeozem Ap fertilized (57.7 μg g —1 ), and Gleysol Ap (66.7 μg g —1 ). Our results demonstrate that the method is well suited to investigate the role of long‐chain fatty acids in humic fractions, whole soils and their particle‐size fractions and can be serve for the differentiation of plant growth and soil management.