Colorimetric Determination of Phosphorus

Fiske CH, Subbarow Y. The colorimetric determination of phosphorus. J Biol Chem 1925 66 375. 

R. M. Pollman, Atomic absorption spectrophotometric determination of calcium and magnesium and colorimetric determination of phosphorus in cheese collaborative study, J. Assoc. Off. Anal. Chem., 74 (1991), 27 -31. 

Cyrus H. Fiske and Yella Pragada Subbarow, J. Biol. Chem., 66 375-400 (1925). The Colorimetric Determination of Phosphorus. 

Kitson, R.E. and Mellon, M.G., Colorimetric determination of phosphorus as molybdivanadophosphoric acid. Industrial and engineering chemistry. Analytical edition, 16, 379, 1944. 

Use a spreadsheet program such as EXCEL or its equivalent to construct a five-point calibration plot. The plot should show absorbance values on the ordinate and concentration as ppm P on the abscissa. Use a least squares regression to fit the experimental points and calculate the correlation coefficient. Calculate the percent error and the confidence interval at 95% probability for the ICV. Report on the unknown ppm P and estimate the confidence interval at 95% probability for both the surface-water sample and the sample given to you by the instructor be sure to include the code for this sample. Review this method in a resource such as Standard Methods for the Examination of Water and Wastewater or other sources of the colorimetric determination of phosphorus and discuss the effect of matric interferences on the precision and accuracy for determining P in environmental samples using the visible spectrophotometric method. A computer program written in BASIC (refer to Appendix C) is available with which to use to... 

Various modifications of the colorimetric determination of phosphorus by the molybdenum blue method are available. The method described above has proved to be the most suitable. 

Molybdenite (M0S2) forms soft, thin flakes, which are very similar to graphite. Molybdenum trioxide (M0O3) is a white powder that is yellow in heat and insoluble in water and most acids. It is easily soluble in alkaline solution, with molybdates being formed. Ammonium molybdate together with phosphates forms a yellow-colored complex and precipitates in nitric acid solutions. If acidified molybdate solutions are treated with reducing agents, they become deep blue (molybdenum blue). Both reactions are used in the colorimetric determination of phosphorus. 

Deans [192] have proposed a method for the colorimetric determination of traces of phosphorus with molybdenum blue, making use of the laser-induced thermal lensing effect. The procedure is described, and the results obtained on samples of sea water and lake water are presented. 

Cembella et al. [40] have described a method for the determination of total phosphorus in seawater. The procedure used magnesium nitrate to oxidise organic compounds before standard molybdate colorimetric determination of ortho-phosphate. The method was applied to several pure organic phosphorus compounds and gave 93-100% recovery of phosphorus. 

Allen, R. J. L. (1940). Micro-determination of phosphorus. (Colorimetric estimation molybdate blue.) Biochem. J. 34, 858. Bellamy, L. J. (1954). Infra-red Spectra of Complex Molecules. Methuen and Co. 

Methylcarbazole reacted with 2,6-dimethyl-4-pyrone in the presence of phosphorus oxychloride generating the pyrylium salt 170. Xanthydrol and thiaxanthydrol condensed with carbazole and 9-methylcarbazole under acid catalysis and sulfuric acid oxidation to give the colored salts 171 (X = O or S) the process has been used for the colorimetric determination of carbazole. ... 

The title, "The Determination of Phosphorus, for example, would interest the present author, but at once questions arise. In what kind of material is the phosphorus determined Is a separation of the element necessary If so, what kind of method is applicable Is a colorimetric method of measurement used If so, what is the color-forming reagent If it is ammonium molybdate, is the system measured molybdophosphoric acid, molybdovanadophosphoric acid, or a heteropoly blue If the latter, what are the reductant and the conditions of reduction To the extent that the title does not answer these and other similar questions, the summary should. 

Bell RD, Doisy EA (1920) Rapid colorimetric methods for the determination of phosphorus in urine and blood. J Biol Chem 44 55-67... 

The deactivated catalyst was studied by several methods scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS), infrared spectroscopy (IR), and by extracting water-insoluble phosphorus. The SEM-EDS studies gave no useful results. IR absorption was measured on samples that were mulled in mineral oil. Comparisons of IR spectra were made with samples of y -alumina and aluminum phosphate. Determination of total P in the deactivated sample, presumed to be present as water-insoluble aluminum phosphate, was made by standard wet chemical analysis dissolution in hot, dilute HCl followed by colorimetric determination of phosphate. ... 

For many scientists involved in the analysis of phosphorus in water, sediment and soil, the only available techniques depend on the colorimetric determination of molybdate-reactive phosphorus, and that which can be made reactive during a digestion step. Molybdate-reactive phosphorus in filtered samples is generally equated to inor-... 

Table 3.2. Analytical parameters for comparison of the inductively coupled plasma mass spectrometry (ICP-MS) and colorimetric methods of phosphorus determination. ...

The widely used method for the determination of this stabiliser is based on the determination of phosphorus. This involves a tedious preliminary digestion with nitric and perchloric acids. Kellum [84] has described a colorimetric method for determining Polygard based on hydrolysis to nonyl phenol, followed by coupfing with p-nitro benzene-diazonium fluoroborate and colorimetric estimation at 550 nm ... 

Shepherd and Davies [175] improved the manipulation of the analysis and the buffering system to permit a more efficient automated determination of NQ3 in the digestion mixture. More recently, Raimbault et al. [87] proposed a method for the simultaneous determination of DOC, DON, and DOP (dissolved organic phosphorus) in seawater based on a persulfate digestion in an autoclave (120°C 1 bar 0.5 h) in slightly alkaline conditions. The digestion mixture was afterward analyzed in a three-channel autoanalyzer for the automatic colorimetric determination of NO3, PO4, and CO2. 

Pelts and Belcher [46] have described a semi-automated method for the simultaneous determination of nitrogen and phosphorus in soil. Up to 40 samples are digested with sulphuric acid using a copper sulphate-sodium sulphate catalyst at 370°C for 2.25h in a thermostatically controlled block. Nitrogen is then determined in the 0.2-2.25% range as ammonia by automatic colorimetric analyses of the indophenol blue complex at 630nm. 

The phosphorus content can be determined by wet oxidation of the starch with sulfuric (or nitric) acid and hydrogen peroxide followed by colorimetric estimation of the phosphomolybdate complex. A detailed procedure for gravimetric determination can be found in AACC method 40-57 (AACC, 2000). However, large sample sizes (2-5 g) are required in this method. 

Wet chemical colorimetric methods are the choice for the accurate determination of the composition of doped thin films. Since early 1960, colorimetry has been used to measure the percentage of phosphorus in PSG (I,... 

Traces of phosphorus, silicon, and arsenic can be determined colorimetrically by complexing with molybdate and reducing the heteropoly anion to a very deep blue color. Absorption spectra in solution of heteropoly blues show charge transfer bands in the visible region with molar extinction coefficients of the order 104 to 10s 123 ... 

If a water sample contains both soluble and insoluble manganese (Mn) compounds and ions, and it is filtered to separate the dissolved and insoluble fractions, and the filtrate and insoluble residue are analyzed separately, the results can be expressed as total dissolved Mn and total suspended or insoluble Mn. Phosphorus (P) can be determined colorimet-rically as the ortho-phosphate ion, P043, in aqueous samples after a reaction that forms an intensely blue-colored derivative. However polyphosphate ions and other ions and compounds containing P do not form this derivative. Total P in a sample can be determined with the same colorimetric procedure after acid hydrolysis and oxidation of all ions and compounds containing P to P04 3. In some elemental analyses the sample is treated with reagents designed to make available for measurement some fraction of an element or elements but not the total amount. For example, a soil sample may be treated with water at pH 3 to simulate the leaching process of acid rain. A total elemental analysis of the filtrate provides information about just those elements solubilized by the mild acid treatment. This can be called the determination of total mild acid leachable elements. 

Adam A, Boulanger J, Azzouzi M, Ers R Colorimetric versus enzymatic determination of serum phosphorus. Clin Chem 1984 30 1724-5. 

In the predominantly AAS scheme, phosphorus and titanium are colorimetrically determined. The results obtained on five replicates of the solution by each method are given in Table III and are compared with the values obtained for this standard at the Indiana Geological Survey.07) The ICPES and AAS results are in very good agreement with each other and with the literature values. The precision and the accuracy of the measurements are 5% for most elements analyzed. 

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