GB/T 5059.6-2007Ferromolybdenum - Determination of phosphorus content - Molybdobismuthylphosphoric blue spectrophotometric method and the molybdenum blue spectrophotometrc method (English PDF)

3.1 Principle

Sample dilute nitric acid, hydrofluoric acid decomposition, perchloric acid, sulfuric acid, phosphorus oxide smoke. Sulfuric smoke after treatment with hydrochloric acid dissolved salts with ammonia

Water to iron hydroxide and iron phosphate is separated from the matrix, most co-precipitation of molybdenum. Sulfuric acid to dissolve the precipitate in sulfuric acid medium with thiosulfate

High sodium reduction of arsenic, phosphorus and bismuth nitrate, ammonium molybdate form a ternary complex, after reduction with ascorbic acid, phosphorus, forming bismuth phosphorus molybdenum blue spectrophotometric

Count on 700nm wavelength measured absorbance.

3.2 Reagents and materials

Unless otherwise indicated in the analysis using only recognized as analytical grade reagents and distilled water or its equivalent purity water.

3.2.1

hydrofluoric acid, rho1.15g/mL.

3.2.2

perchloric acid, rho1.67g/mL.

3.2.3

ammonia, rho0.90g/mL.

3.2.4

nitric acid, 1 + 2.

3.2.5

hydrochloric acid, 1 + 2.

3.2.6

sulfuric acid, 1 + 1.

3.2.7

sulfate, 1 + 4.

3.2.8

sulfuric acid, 1 + 7.

3.2.9

sulfate, 1 + 50.

3.2.10 sodium thiosulfate solution, 10g/L

1L containing 20g of anhydrous sodium sulfite, now equipped with time.

3.2.11 bismuth nitrate solution, 30g/L

Weigh 30g of bismuth nitrate [Bi (NO3) 3 · 5H2O], was dissolved in 100mL nitrate (1.42g/L)

In until completely dissolved by adding 900mL water, 4g urea, and mix.

3.2.12 ammonium molybdate solution, 15g/L

Weigh 15g of ammonium molybdate [(NH4) 6Mo7O24 · 4H2O], placed in 400mL beaker, add

200mL water, warm dissolved by adding 800mL of water after filtration, and mix.

3.2.13 ascorbic acid solution, 10g/L

Ethanol (1 + 1), when using the existing service.