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Optimizing phosphorus characterization in animal manures by solution phosphorus-31 nuclear magnetic resonance spectroscopy

Optimizando la Caracterización del Fósforo en Abonos Animales por Espectroscopia de Resonancia Magnética Nuclear de Fósforo -31

Turner, Benjamin L. (2004) Optimizing phosphorus characterization in animal manures by solution phosphorus-31 nuclear magnetic resonance spectroscopy. Journal of Environmental Quality. 33:757-766.

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A procedure involving alkaline extraction and solution 31P nuclear
magnetic resonance (NMR) spectroscopy was developed and optimized
for the characterization of P in animal manures (broiler, swine,
beef cattle). Inclusion of ethylenediaminetetraacetic acid (EDTA) in
the alkaline extraction solution recovered between 82 and 97% of
the total P from the three manures, which represented a significant
improvement on recovery in NaOH alone. Low concentrations of
paramagnetic ions in all manure extracts meant that relatively long
delay times (>5 s) were required for quantitative analysis by solution
31P NMR spectroscopy. The manures contained inorganic orthophosphate,
orthophosphate monoesters, orthophosphate diesters, and inorganic
polyphosphates, but results were markedly influenced by the
concentration of NaOH in the extractant, which affected both spectral
resolution and the apparent P composition of the extracts. For example,
extraction of swine manure and broiler litter with 0.5 M NaOH +
50 mM EDTA produced remarkable spectral resolution that allowed
accurate quantification of the four signals from phytic acid, the major
organic P compound in these manures. In contrast, more dilute NaOH
concentrations produced considerable line broadening that obscured
individual signals in the orthophosphate monoester region of the
spectra. Spectral resolution of cattle manure extracts was relatively
unaffected by NaOH concentration. Improvements in spectral resolution
of more concentrated NaOH extracts were, however, compromised
by the disappearance of phospholipids and inorganic polyphosphates,
notably in swine and cattle manure extracts, which indicated
either degradation or a change in solubility. The optimum extraction
conditions will therefore vary depending on the manure type and the
objectives of the study. Phytic acid can be accurately quantified in
swine manure and broiler litter by extraction with 0.5 M NaOH +
50 mM EDTA, while a more dilute NaOH concentration should be
used for complete P characterization or comparison among different
manure types.

Item Type: Article
NWISRL Publication Number: 1124
Subjects: Manure > Chemistry
Research methodology
Mass Import - autoclassified (may be erroneous)
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:50
Last Modified: 07 Nov 2016 16:45
Item ID: 178