GB/T 4701.7-2009Ferrotitanium - Determination of phosphorus content - Molybdobismuthylphosphoric blue spectrophotometric method and the molybdenum blue spectrophotometric method (English PDF)

3.1 Principle

A specimen in nitric acid, hydrofluoric acid decomposition, sulfuric acid and perchloric smoke phosphorus oxide, with sodium hydroxide and iron, titanium and phosphorus to form a precipitate separated. filter

Was acidified with sulfuric acid in sulfuric acid medium, sodium thiosulfate reducing high arsenic, bismuth nitrate and phosphorus, molybdenum, bismuth molybdate forming phosphorus ligands three yuan

Was, after ascorbic acid with phosphorus forming bismuth phosphorus molybdenum blue, 700nm wavelength measured absorbance on a spectrophotometer, the calibration curve

Quality Richard phosphorus content in the sample is calculated phosphorus.

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

nitrate, rho1.42g/mL.

3.2.2

hydrofluoric acid, rho1.15g/mL.

3.2.3

perchloric acid, rho1.67g/mL.

3.2.4

sulfuric acid, rho1.84g/mL.

3.2.5

sulfate, 1 + 5.

3.2.6

sulfate, 1 + 7.

3.2.7 sodium hydroxide solution, 200g/L

Store in plastic bottle.

3.2.8 sodium thiosulfate solution, 10g/L

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

3.2.9 bismuth nitrate solution, 30g/L

Weigh 15g of bismuth nitrate [Bi (NO3) 3 · 5H2O], placed in 600mL beaker, add 50mL

Nitrate (1.42g/mL), and until completely dissolved, 2g of urea, 450mL of water, and mix.

3.2.10 ammonium molybdate solution, 35g/L

Weigh 3.5g of ammonium molybdate [(NH4) 6Mo7O24 · 4H2O], placed in 200mL beaker, add

Into 100mL water, warmed to dissolve and mix. Use filtered.

3.2.11 ascorbic acid solution, 10g/L

Ascorbic Weigh 5g, placed in 600mL beaker was added 500mL ethanol (1 + 1), mixed uniform. Formulated with time.

3.2.12 ammonium ferric sulfate solution, 90g/L

Weigh 45g of ammonium ferric sulfate (NH4Fe (SO4) 2 · 12H2O) placed in 600mL beaker,

Was added 85mL of water, add 15mL sulfuric acid (3.2.5), dissolved completely, was added 400mL of water, and mix.