Acid Hydrochloric Phosphomolybdic

Ammonium molybdate Addition of 2 to 3 ml of excess reagent to approximately 0.5-ml sample gives yellow precipitate of ammonium phosphomolybdate, which is soluble in ammonia solution and in solutions of caustic alkalis large quantities of hydrochloric acid interfere... 

Many color reagents are applicable to the oligosaccharides. Some of those used are ammoniacal silver nitrate,60 resorcinol-hydrochloric acid for inulin hydrolyzates,137 acidic benzidine for maltodextrins,138 Bromo-phenol Blue or p-anisidine-hydrochloric acid for galactosiduronic acids,130 and alkaline copper reagent with phosphomolybdic acid for dextrins.71... 

An ammonium phosphomolybdate precipitate is treated as described under (2c) (p. 182) for conversion into MgNH4P04. The washed precipitate of MgNH4P04 may be determined volumetrically by solution in a known quantity in excess of standard hydrochloric acid and baek-titration with decinormal alkali using methyl orange, thus... 

Phosphomolybdic acid reagent (H3[PMol2O4.0]) molybdenum blue is produced by antimony(III) salts. Of the ions in Group II, only tin(II) interferes with the test. The test solution may consist of the filtered solution obtained by treating the Group IIB precipitate with hydrochloric acid the antimony is present as.Sb3+ and the tin as Sn4+, which has no effect upon the reagent. 

Collect in bubbler with hydrochloric acid derivatize with phosphomolybdic acid... 

If the ammonium phosphomolybdate concentration is too high, a yellow precipitate is formed. This has often been used deliberately in test procedures, but such methods suffer from tire reproducibility problems often encountered in tests based on precipitation. The environment must be acidic but the presence of nitric acid enhances the risk of ammonium phosphomolybdate precipitation, and hydrochloric acid gives a yellow precipitate of molybdic acid, H2M0O4. The presence of other ammonium salts also raises the risk of an unwanted ammonium phosphomolybdate precipitation provoked by the common ion effect. 

A mixture of nicotinic acid, nicotinamide, trigonelline and tryptophan can be separated chromatographicaUy, using as solvent a 5 i mixture of n-butanol and concentrated hydrochloric acid, saturated with water. Tryptophan is revealed by ninhydrin, while nicotinic acid, nicotinamide and trigonelline are detected with phosphomolybdic acid reagent and the color developed with stannous chloride, which reduces the phosphomolybdic acid to give a blue spot. The Rf values for the butanol-HCl solvent are nicotinic acid, 0.37 nicotinamide, 0.28 trigonelline, 0.38 and tryptophan, 0.62. 

Evaluation reagents I ethanolic sulfuric acid, 2 tetrazolium blue, 3 antimony(III)chloride, 4 chloramine T. 5 xanihidrol, 6 phosphoric acid, 7 iodine, 8 hydrochloric acid, 9 Dragendorff reagent, 10 phosphomolybdic acid, II p-acelylaminobcnzaldehydc scmicarbazonc, 12 1,4-dihydrazinophtalazine. 

The occurrence of redox reaction (3) and hence the presence of organic materials, can be recognized directly by a dark color due to finely divided silver, if considerable quantities of the latter have been formed. Because of much greater sensitivity, it is better to detect metallic silver through its reaction with a hydrochloric acid solution of phosphomolybdic acid. Silver... 

Reagents 1) Silver arsenate prepared by the action of sodium arsenate on silver nitrate. The precipitate may be isolated by centrifuging. The product is washed thoroughly and then dried at 110 C 2) 3% solution of phosphomolybdic acid in 1 1 hydrochloric acid... 

If the tin occurs originally in the bivalent condition, the test may be carried out as described, and antimony salts do not interfere. If however, quadrivalent tin is present, it must be reduced to the stannous condition. This can be done by placing 1 or 2 drops of the test solution in a small porcelain crucible, and warming with either a small strip of magnesium ribbon or a tiny piece of zinc, plus a few drops of concentrated hydrochloric acid, until the metal dissolves. A drop of this solution is placed on ammonium phosphomolybdate paper. Any metallic antimony, which is precipitated as a black powder, does not interfere with the test for tin. 

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