Quantification of myo-inositol hexakisphosphate in alkaline soil extracts by solution 31P NMR spectroscopy and spectral deconvolution

La cuantificación de myoinositol hexakisfosfato en extractos de suelos alcalinos por la solución de espectroscopia 31P NMR y la deconvolucion del espectro

Turner, Benjamin L. and Mahieu, Nathalie and Condron, Leo M. (2003) Quantification of myo-inositol hexakisphosphate in alkaline soil extracts by solution 31P NMR spectroscopy and spectral deconvolution. Soil Science. 168(7):1-10.

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Abstract

Inositol phosphates are the dominant class of organic phosphorus (P)
compounds in most soils, but they are poorly understood because they
are not easily identified in soil extracts. This study reports a relatively
simple technique using solution 31P NMR spectroscopy and spectral deconvolution
for the quantification of myo-inositol hexakisphosphate
(phytic acid), the most abundant soil inositol phosphate, in alkaline soil
extracts. An authentic myo-inositol hexakisphosphate standard added to
a re-dissolved soil extract gave signals at 5.85, 4.92, 4.55, and 4.43 ppm
in the ratio 1:2:2:1. Spectral deconvolution quantified these signals accurately
(102 ± 4%) in solutions containing a mixture of model P compounds
by resolving the envelope of signals in the orthophosphate monoester
region. In NaOH-EDTA extracts from a range of lowland
permanent pasture soils in England and Wales, concentrations of myo-inositol
hexakisphosphate determined by spectral deconvolution ranged
between 26 and 189 mg P kg- 1 soil, equivalent to between 11 and 35%
of the extracted organic P. Concentrations were positively correlated
with oxalate-extractable aluminum and iron but were not correlated with
total carbon, total nitrogen, clay, or the microbial biomass. This suggests
that myo-inositol hexakisphosphate accumulates in soils by mechanisms
at least partially independent of those controlling organic matter stabilization
and dynamics. Furthermore, myo-inositol hexakisphosphate concentrations
were positively correlated with plant-available inorganic P
and negatively correlated with the carbon-to-organic P ratio, suggesting
that biological P availability may, in part, regulate myo-inositol hexakisphosphate
concentrations in soils, perhaps because organisms capable
of degrading this compound are favored in more P-limited environments.
Solution 31P NMR spectroscopy and spectral deconvolution offers
a relatively simple method of quantifying myo-inositol hexakisphosphate
in soil extracts.

Item Type:	Article
NWISRL Publication Number:	1108
Subjects:	Soil > Chemistry > Phosphorous Research methodology Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:50
Last Modified:	08 Nov 2016 20:09
Item ID:	166
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/166