Interference of colloidal particles in the determination of orthophosphate concentrations in soil water extracts

Abstract Accurate determination of orthophosphate (P) in soil solutions is a prerequisite for rigorously assessing soil P availability for plants as well as the potential risk of P transfer to water bodies. Although P is usually measured on extracts filtered at 0.45 μm, little is known on the potential interfences due to the presence of colloidal particles. This work was conducted to study the influence of colloidal particles on P concentration by measuring it both by the phosphoantimonylmolybdenum blue colorimetry and ion chromatography in soil water extracts filtered at 0.45, 0.2, or 0.025 μm. Results strongly suggest that direct measurements with colorimetry might lead to an overestimation of the P concentration due to the solubilization of P‐containing particles in the acid medium prevailing in the solution during colorimetric essay. In the present study, the largest overestimations were observed in soil extracts rich in iron (Fe) and aluminum (Al) that had been filtered at 0.45 μm, on the opposite th...

[1]  I. Novozamsky,et al.  Automated determination of trace amounts of phosphate in soil extracts using malachite green. , 1993 .

[2]  W. Stumm,et al.  TRACE METALS IN NATURAL WATERS; DIFFICULTIES OF INTERPRETATION ARISING FROM OUR IGNORANCE ON THEIR SPECIATION , 1973 .

[3]  A. Edwards,et al.  Processes Influencing Dissolved Organic Nitrogen, Phosphorus and Sulphur in Soils , 1993 .

[4]  S. R. Olsen,et al.  Test of an Ascorbic Acid Method for Determining Phosphorus in Water and NaHCO3 Extracts from Soil , 1965 .

[5]  S. Blomqvist,et al.  Interference from Arsenate, Fluoride and Silicate When Determining Phosphate in Water by the Phosphoantimonylmol Ybdenum Blue Method , 1993 .

[6]  M. Brossard,et al.  Reactions controlling the cycling of P in soils , 1995 .

[7]  M. K. John.  COLORIMETRIC DETERMINATION OF PHOSPHORUS IN SOIL AND PLANT MATERIALS WITH ASCORBIC ACID , 1970 .

[8]  A. Jungk,et al.  Separation of phosphorus bound to organic matrices from inorganic phosphorus in alkaline soil extracts by ultrafiltration , 1991 .

[9]  J. Gerke.  Orthophosphate and organic phosphate in the soil solution of four sandy soils in relation to pH‐evidence for humic‐FE‐(AL‐) phosphate complexes , 1992 .

[10]  G. Aiken,et al.  Isolation and Chemical Characterization of Dissolved and Colloidal Organic Matter , 1993 .

[11]  J. Fardeau.  Le phosphore assimilable des sols : sa représentation par un modèle fonctionnel à plusieurs compartiments , 1993 .

[12]  R. Yost,et al.  Potential errors in the use of the Murphy and Riley method for determination of phosphorus in soil extracts , 1994 .

[13]  Philip M. Haygarth,et al.  Short-term changes in the molybdate reactive phosphorus of stored soil waters , 1995 .

[14]  L. Zibilske,et al.  DETERMINATION OF LOW CONCENTRATIONS OF PHOSPHORUS IN SOIL EXTRACTS USING MALACHITE GREEN , 1991 .

[15]  P. Veldhoven,et al.  Inorganic and organic phosphate measurements in the nanomolar range. , 1987, Analytical biochemistry.

[16]  J. P. Riley,et al.  A modified single solution method for the determination of phosphate in natural waters , 1962 .

[17]  M. Stainton.  Errors in Molybdenum Blue Methods for Determining Orthophosphate in Freshwater , 1980 .

[18]  W. Dick,et al.  Determination of Orthophosphate in Aqueous Solutions Containing Labile Organic and Inorganic Phosphorus Compounds , 1977 .

[19]  D. Laxen,et al.  Comparison of filtration techniques for size distribution in freshwaters , 1982 .