GB/T 4699.3-2007Ferrochromium, silicochromium and nitrogen-bearing ferrochromium -Determination of phosphorus content - Molybdobismuthylphosphoric blue spectrophotometric method and the molybdenum blue spectrophotometric method (English PDF)

3.1 Principle

Samples with hydrochloric acid - hydrogen peroxide or with nitric acid - hydrofluoric acid decomposition of perchlorate in the state smoke, play with hydrochloric acid chromium; or anhydrous carbonate

Sodium - sodium peroxide mixed flux melt decomposition. In sulfuric acid, sodium thiosulfate reducing high arsenic, phosphorus and bismuth nitrate, ammonium molybdate form three

Yuan complex, forming bismuth phosphorus molybdenum blue by ascorbic reducing phosphorus, measured absorbance at 700nm wavelength spectrophotometer.

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

sodium peroxide, solid.

3.2.2

anhydrous sodium carbonate solids.

3.2.3

perchloric acid, rho1.67g/mL.

3.2.4

hydrochloric acid, rho1.19g/mL.

3.2.5

Hydrogen peroxide, rho1.10g/mL, pure class distinctions.

3.2.6

nitrate, rho1.42g/mL.

3.2.7

hydrofluoric acid, rho1.15g/mL.

3.2.8

sulfuric acid, 1 + 1.

3.2.9 sulfate, 1 + 2

3.2.10 sodium sulfite solution, 100g/L

Weigh 100g of anhydrous sodium sulfite, dissolved in water, diluted with water to 1000mL.

3.2.11 sodium thiosulfate solution, 5g/L

1L containing 10g of anhydrous sodium sulfite, formulated with time.

3.2.12 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.

3.2.13 ammonium molybdate solution, 33g/L

Weigh 33g of ammonium molybdate [(NH4) 6Mo7O24 · 4H2O], placed in 400mL beaker, add […]