The use of hypobromite oxidation to evaluate two current methods for the estimation of inositol polyphosphates in alkaline extracts of soils

Abstract

Two current methods (McKercher and Anderson and Steward and Tate 18 ) for the estimation of inositol polyphosphates in soil extracts were examined for accuracy by subjecting the inositol polyphosphate fraction obtained by each method to oxidation with alkaline hypobromite. Anion-exchange chromatography of the resistant phosphate showed that with both methods a large proportion of the organic phosphorus in the fraction was neither inositol pentakisphosphate nor inositol hexakisphosphate. The results of methods for the estimation of these compounds in soil extracts which do not include an oxidation with alkaline hypobromite must therefore be suspect. 495 Copyright© 1981 by Marcel Dekker, Inc. 496 IRVING AND.COSGROVE

Organic phosphorus in Madagascan rice soils

“…Concentrations vary widely, although much of the early literature must be regarded with caution for analytical reasons (Irving and Cosgrove, 1981;Turner et al, 2002). Data for rice soils is limited, although in a range of soils from Bangladesh, of which some were presumably from rice paddies, inositol hexakisphosphate (stereoisomers were not identified separately) constituted between 18 and 150 mg P kg − 1 and between 9% and 83% of the soil organic phosphorus (Islam and Ahmed, 1973).…”

Extraction of soil organic phosphorus

“…Despite its widespread use, the McKercher and Anderson [81] method tended to overestimate the concentration of inositol phosphates, because other organic phosphorus compounds were present in the chromatographic fractions that supposedly contained only inositol phosphate [68]. This can be overcome using hypobromite oxidation [86], which oxidises soil organic matter without degrading inositol phosphates [87,88].…”

“…Furthermore, the unextractable fraction is often assumed to be organic phosphorus, yet there is no direct evidence for this. This can be investigated in future studies by subjecting the residual fraction to hypobromite oxidation and solution 31 P NMR spectroscopy to determine the presence of higher-order inositol phosphates [67,68], or by solid-state 31 P NMR to determine the possible presence of phosphonates [69].…”

“…A detailed assessment of such techniques is outside the scope of this review, but procedures have been developed to extract phospholipids [78,79], sugar phosphates [80], inositol phosphates [68,81], adenosine triphosphate [82], nucleic acids, and nucleotides [22,83,84]. They are generally laborious and often limited by incomplete extraction or difficulties with post-extraction analysis [14].…”

A Novel Technique for the Pre-Concentration and Extraction of Inositol Hexakisphosphate from Soil Extracts with Determination by Phosphorus-31 Nuclear Magnetic Resonance

“…The prevalence of these associations in soils may necessitate the use of hypobromite oxidation prior to pre-concentration. This technique oxidizes all organic matter except inositol phosphates (Irving and Cosgrove, 1981;Nanny and Minear, 1997) and would free IP6 to solution, from where it could be extracted, pre-concentrated and analyzed by the Sephadex-NMR procedure.…”