Determination of Total Phosphate

K.E. Williams, S.J. Haswell, D.A. Barclay, G. Preston, Determination of total phosphate in waste waters by on-line microwave digestion incorporating colorimetric detection, Analyst 118 (1993) 245. 

A. G. Fogg, G. C. Cripps, and B. J. Birch, Static and Flow Injection Volt-ammetric Determination of Total Phosphate and Soluble Silicate in Commercial Washing Powders at a Glassy Carbon Electrode. Analyst, 108 (1983) 1485. 

L. Xu, X. Liu, Y. Yang, and F. Yan, Determination of Total Phosphate in Plant Samples by Flow Injection Analysis [in Chinese]. Dongbei Linx-ueyuan Xuebao, 13 (1985) 33. 

G. Wei and H. Ma, Determination of Total Phosphate in Samples from Trees by Flow Injection Analysis—Molybdenum Yellow Photometric Method [in Chinese]. Linye Daxue Xuebao, 3 (1986). 

Fogg, A.G., Cripps, G.C., and Birch, B.J., Static and flow injection voltammetric determination of total phosphate and soluble silicate in commercial washing powders at a glassy carbon electrode. Analyst 108,1485,1983. 

Ln(II) in LnFj Ln(II) were determined after samples dissolution in H PO in the presence of a titrated solution of NFI VO, which excess was titrated with the Fe(II) salt. It was found that dissolution of the materials based on CeF CeFj in H PO does not change the oxidation state of cerium, thus phosphate complexes of Ce(III, IV) can be used for quantitative spectrophotometric determination of cerium valence forms. The contents of Ln(II, III) in Ln S LnS may be counted from results of the determination of total sulfur (determined gravimetric ally in BaSO form) and sum of the reducers - S and Ln(II) (determined by iodometric method). 

Al-Shawi, A. W. and Dahl, R., Determination of total chromium in phosphate... 

Schnepfe [4] has described a method for the determination of total iodine and iodate in seawater. One per cent aqueous sulfamic acid (1 ml) is added to seawater (10 ml), then it is filtered, if necessary, and the pH adjusted to 2. After 15 min, 1 ml 0.1 M sodium hydroxide and 0.5 ml 0.1 M potassium permanganate are added and the steam bath heated for 1 h. The cooled solution is filtered, the residue washed, the filtrate plus washings is diluted to 16 ml and 1 ml of a 0.25 M phosphate solution (containing 0.3 pg iodine as IOj per... 

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. 

The coefficient of variation obtained for the determination of total phosphorus in sediment at the 1400ppm level was 2.5%. Some 98-100% recovery of inorganic phosphate was obtained in spiking experiments carried out on sediments. 

Tissue distribution was examined at five time points, with separate determinations of total 4C, tris(2,3-dibromopropyl) phosphate and bis(2,3,-dibromopropyl) phosphate. The results confirmed the rapid disappearance of tris(2,3-dibromopropyl) phosphate, this being detected only at 5 and 30 min. Bis(2,3-dibromopropyl) phosphate was the major component in blood, lung, muscle and fat and had a long elimination period. At five days after dosing, there was significant retention of in the kidney, this comprising various polar components with some bis(2,3-dibromopropyl) phosphate also detected. The extensive biliary excretion of tris(2,3-dibromopropyl) phosphate-related radioactivity and low faecal elimination of the radiolabel indicate that enterohepatic circulation contributes to the retention of in the body (Lynn et al., 1982). 

The determination of total iron in soils has been discussed by Jayman et al. [103]. This method is based on the formation of the 1,10-phenanthroline complex of iron. Unfortunately, aluminium also forms a similar complex which exhibits identical absorption characteristics. However, iron can be determined without interference following the removal of aluminium and phosphates. In this method, finely ground soil is ignited overnight at 450 °C and the residue... 

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. 

Total hydrolysable phosphate in water samples was determined after preliminary hydrolysis with sulphuric acid solution. To 50 ml samples was added 0.05 ml phenolphthalein indicator and, in cases where a red colour was observed, the color was discharged with drops of 30 % sulphuric acid solution. To each sample, 1 ml of 30 % sulphuric acid solution was added and diluted to 100ml. The samples were boiled for at least 90 minutes on a hot plate and the final digest was reduced to 25 to 50 ml. To each digest, 6 N sodium hydroxide solution was added until a faint pink color was observed. The faint pink colour was then discharged by adding 50% hydrochloric acid solution and the sample then proceeded to determination of the phosphate using vanadate-molybdate method as in the case of total reactive phosphate. Both the standards and blanks for determination of total hydrolysable phosphate were treated in the same manner as the samples. 

The most common approach to phosphorus determination is the assessment of phosphate in wet chemistry. Therefore, the majority of samples should be dissolved before analysis. Solid samples are decomposed by alkali or acid treatment silicate is dissolved by treatment with fluoric acid. Samples of biological material are reduced to ash using an appropriate laboratory oven or are digested with hot oxidative acids. A direct phosphate assessment is advised only in some water samples. The determination of total phosphoms is not used to identify soil fertility due to phosphorus content rather, water extracts are used of various pH and ionic strength. 

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. ... 

To determine the total phosphates in a urine 50 c.c. are placed in a beaker, 5 c.c. sodium acetate solution are added the mixture is heated on the water-bath, and the uranium solution delivered from a burette, until a drop, removed from the beaker and brought in contact with a drop of ferrocyanid solution, produces a brown tinge. The burette reading, multiplied by 0.005, gives the amount of P Os in 50 c.c. urine and this, multiplied by the amount of urine passed in 24 hours, gives the daily elimination. 

If determination of hydrogen phosphate and of total phosphorus is conducted in parallel, the difference between the two results provides a measure of... 

Flame atomic absorption spectrometry The determination of magnesium by FAAS is performed in diluted samples using the resonance line 285.2 nm and a stoichiometric air-acetylene flame. The interference due to phosphate is eliminated by the addition of LaCls. FAAS is used for the most reliable determination of total magnesium in physiological samples and has been chosen as the basis for the reference method. 

If no other phosphate is present, determine the total phosphate content of both product and raw material. 

The first and most critical analytical step for the determination of total phosphorus is the acid hydrolysis and the digestion of condensed phosphates and organic phosphoms for their conversion into orthophosphate and subsequent determination of this ion by a multitude of different flow analytical techniques [110]. 

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