Ammonium molybdophosphate

The application of ammonium molybdophosphate and other unsoluble in water salts of heteropolyacids for preconcentration of heavy metals of first group elements Cs(I), Ag(I), Cu(I) and also T1(I), Hg(I) (M(I)) is described. The shortcomings of ammonium molybdophosphate as ionexchanger are ... 

Discussion. When a solution of an orthophosphate is treated with a large excess of ammonium molybdate solution in the presence of nitric acid at a temperature of 20-45 °C, a precipitate is obtained, which after washing is converted into ammonium molybdophosphate with the composition (NH4)3[P04,12Mo03]. This may be titrated with standard sodium hydroxide solution using phenolph-thalein as indicator, but the end point is rather poor due to the liberation of ammonia. If, however, the ammonium molybdate is replaced by a reagent containing sodium molybdate and quinoline, then quinoline molybdophosphate is precipitated which can be isolated and titrated with standard sodium hydroxide ... 

The main advantages over the ammonium molybdophosphate method are (1) quinoline molybdophosphate is less soluble and has a constant composition, and (2) quinoline is a sufficiently weak base not to interfere in the titration. 

Determination of phosphate as ammonium molybdophosphate. This may be readily effected by precipitation with excess of ammonium molybdate in warm nitric acid solution arsenic, vanadium, titanium, zirconium, silica and excessive amounts of ammonium salts interfere. The yellow precipitate obtained may be weighed as either ammonium molybdophosphate, (NH4)3[PMo12O40], after drying at 200-400 °C, or as P205,24Mo03, after heating at 800-825 °C for about 30 minutes. 

Discussion. Phosphate ion is determined nephelometrically following the formation of strychnine molybdophosphate. This turbidity is white in colour and consists of extremely fine particles (compare ammonium molybdophosphate, which is yellow and is composed of rather large grains). The precipitate must not be agitated, as it tends to agglomerate easily it is somewhat sensitive to temperature changes. 

The AOAC alkalimetric ammonium molybdophosphate and photometric molybdovanadate methods for animal feed are described by Padmore (1990, pp. 87-88), and for plants by Isaac (1 990, p. 56). A spectrophotometric molybdovanadate procedure is also described in MAFF/ADAS (1986, pp. 181-182). The official Bran-rLuebbe AutoAnalyzer method for phosphate in soil, plant and fertilizer extracts is reproduced with permission in Appendix 6. 

Todd, T.A., Mann, N.R., Tranter, T.J., Sebesta, F., John, J., Motl, A. Cesium sorption from concentrated acidic tank wastes using ammonium molybdophosphate-polyacrylo-nitrile composite sorbents. J. Radioanal. Nucl. Chem. (2002), 254 (1), 47-52. 

Some chemical modifiers behave in other ways—they decrease analyte volatility or concomitant volatility—so that concomitants (matrix) are volatilized during the cleaning step. Examples of the first behavior are certain organic acids, such as ascorbic or citric acids, which react with volatile elements, thereby diminishing their volatilities. An example of the second type of behavior is the use of ammonium molybdate, which reacts with phosphate ions to form the highly refractory ammonium molybdophosphate. 

The radiochemical procedure for the determination of Cs in aqueous samples is based on the batch extraction of caesium onto a microcrystalline cation exchanger, ammonium molybdophosphate (AMP), and subsequent purification from potassium and rubidium activities by ion-exchange separation using a strongly acidic cation exchange resin (BIO-REX-40). Natural K and Rb have radioactive isotopes that interfere with the beta counting of Cs. The purification of caesium is also necessary to determine the chemical recovery. 

Zirconium phosphate, tungstate and molybdate, ammonium molybdophosphate and tungstophos-phate, hydrous oxides... 

In the separation of caesium, the following inorganic cation exchangers are particularly useful potassium cobalt(II) hexacyanoferrate(II) [12,13], potassium copper(II) and nickel(II) hexacyanoferrates(II) [14], ammonium molybdophosphate [13,15], zirconium molybdoarsenate [16], thallium tungstophosphate [17], and tin molybdosilicate [18]. Rubidium has been selectively isolated on columns filled with titanium tungstoarsenate [19] or titanium ferricyanide [20]. Ammonium molybdoarsenate has been used to separate potassium from sodium [21]. 

In order to separate tungsten from metals that form hydroxides insoluble in strongly alkaline media e.g., Fe, Ti, Mn, Mg), the sample is fused with Na2C03 or Na202, and the melt is leached with water. Mo, Cr, V, and As pass into the solution together with W. Tungsten has also been separated with Mn02aq as the collector [44], or with ammonium molybdophosphate [45]. 

Ammonium phosphofluoridate. See Ammonium monofluorophosphate Ammonium phosphomolybdate CAS 54723-94-3 EINECS/ELINCS 234-714-0 Synonyms Ammonium molybdophosphate Ammonium-12-molybdophosphate Molybdophosphoric acid ammonium salt Phosphomolybdic acid, ammonium salt Classiheation Metal-ates Empin cal H12M012N3O40P Formula (NH4)3PMoi2O40 XH2O or (NH4)3P04 I2M0O3 3H2O... 

Hydrogen phosphate ions react with ammonium molybdate to form ammonium molybdophosphate ... 

The three formulae are the various forms of notation which are used for ammonium molybdophosphate in chemical literature). 

The ammonium molybdophosphate is extracted with a benzene/isobutyl alcohol mixture and reduced in the organic phase with acid tin (II) chloride solution to intensely blue-coloured phosphorus molybdenum blue ... 

Ammonium molybdophosphate on filter paper 2,4 -Diaminodiphenyl hydrochloride in HCI 8-Quinolinol (oxide) soln in ethanol... 

Zirconium(IV) phosphate, tungstate, and molybdate titanium(TV) silicate ammonium molybdophosphate and tungstophosphate hydrous oxides... 

The general tendency to apply RNAA for the determination of trace elements when high sensitivity and precision are required can be confirmed. Methods have also been developed for multielement determinations by RNAA. These methods are generally based on complicated separation schemes and usually combine several individual procedures. Randa et al. (2003) reported a method for the determination of REEs, Cs, and Rb combining the REE separation based on oxalate precipitation with the Cs-Rb separation using ammonium molybdophosphate (AMP). Tian et al. (2001) published an RNAA method for the determination of REEs, U, and Ba consisting of a fluoride precipitation of REE and U, and a Ba sulfate precipitation. According to another RNAA method, U and Th determination was based on fluoride precipitation of the analyte nuclides (Np and Pa), while Sr was precipitated as sulfate. Combined procedures of Zaidi were briefly reviewed in O Sect. 30.5.3.1 (see also Zaidi et al. 2001). 

Silica is the base for an ammonium molybdophosphate exchanger which can be used for recovering cesium ions from acid solution (548, 549). Kaletka and Konecny also use silica gel as a support for insoluble nickel, copper, cadmium, or zinc hexa-cyanoferrates, which act as cation exchangers. They can remove traces of cesium ions even from strong nitric acid solution. Exchange capacities of the diflerent compounds were measured (550). ... 

Polyanions. A test for PO4 involves the formation of a yellow precipitate of ammonium molybdophosphate, (NH4)3PMoj204o(HN03)jH20, on the addition of nitric acid and ammonium molybdate, (NH4) Mor024(H20)4. No redox occurs. Determine the oxidation number of Mo In the polyanions PMoi20V and M07O24 . 

Development of Novel "Sponge-Type" Sorbent for Elimination of CS Preparation of Ammonium Molybdophosphate - Polyurethane Foam (AMP-PUF) Composite and its Sorption Behavior... 

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