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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #205260
Title: Evaluation of Phosphorus Characterization in Ileal Digesta, Manure, and Litter Samples: 31P-NMR vs. HPLC

Author
item Leytem, April
item Kwanyuen, Prachuab
item PLUMSTEAD, P - N. CAROLINA STATE UNIV.
item MAGUIRE, R - VIRGINIA TECH
item BRAKE, J - N. CAROLINA STATE UNIV.

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2007
Publication Date: 3/1/2008
Citation: Leytem, A.B., Kwanyuen, P., Plumstead, P.W., Maguire, R.O., Brake, J. 2008. Evaluation of Phosphorus Characterization in Ileal Digesta, Manure, and Litter Samples: 31P-NMR vs. HPLC. Journal of Environmental Quality. 37:494-500.

Interpretive Summary: New analytical techniques such as 31-Phosphorus Nuclear Magnetic Resosonance Spectroscopy (31P-NMR) have become popular for characterizing phosphorus (P) in manures and litter. To date, there has been no published work evaluating P quantification in manure/litter samples with 31P-NMR compared to more traditional and accepted methods, and there has been some skepticism as to the validity of this data. We evaluated the characterization and quantification of P of ileal digesta, manure, and litter from broilers using 31P-NMR and compared this to a more traditional high performance liquid chromatography (HPLC) method. Characterization of the samples by 31P-NMR indicated that the majority of P in all of these samples was in the form of either orthophosphate or monoester phosphate compounds, primarily inositol phosphates. When we compared the quantification of myo-inositol hexakisphosphate (phytate) in all samples by the two methods, they produced almost identical results. We also compared the concentration of total monoester P determined with 31P-NMR with the total inositol P content determined with HPLC and found these two values to be almost identical as well. We therefore concluded that using 31P-NMR to quantify organic P in broiler ileal digesta, manure, and litter with was very consistent to that determined with HPLC analysis, even though the two extraction and quantification methods are quite different. This suggests that 31P-NMR is a very reliable method for quantifying P compounds in manure/litter samples.

Technical Abstract: Using 31-Phosphorus Nuclear Magnetic Resosonance Spectroscopy (31P-NMR) to characterize phosphorus (P) in manures and litter has become prevalent in the area of nutrient management. To date, there has been no published work evaluating P quantification in manure/litter samples with 31P-NMR compared to more traditional and accepted methods, and there has been some skepticism as to the validity of this data. To evaluate the use of 31P-NMR to quantify organic P in ileal digesta, manure, and litter from broilers, we compared results obtained from both 31P-NMR and a more traditional high performance liquid chromatography (HPLC) method. Results from 31P-NMR indicated that the majority of P in all of these samples was in the form of either orthophosphate or monoester phosphate compounds, primarily inositol phosphates. The quantification of myo-inositol hexakisphosphate (phytate) in all samples by the two methods was very consistent with linear regressions having slopes ranging from 0.94 to 1.07 and r squared values of 0.84 to 0.98. We compared the concentration of total monoester P determined with 31P-NMR with the total inositol P content determined with HPLC and found a strong linear relationship between the two measurements having slopes ranging from 0.91 to 1.08 and r squared values of 0.73 to 0.95. Quantification of organic P in broiler ileal digesta, manure, and litter with 31P-NMR was very consistent to that determined with HPLC analysis, even though the two extraction and quantification methods are quite different. This suggests that 31P-NMR is a very reliable method for quantifying P compounds in manure/litter samples.