GB/T 20166.2-2012Chemical analysis methods of rare earth polishing powder - Part 2: Determination fluorine content - Ion selective electrode analysis (English PDF)

3.1

anhydrous sodium carbonate.

3.2

sodium peroxide.

3.3

Sodium hydroxide solution (10g/L).

Secondary ion exchange water to 3.4.

3.5

hydrochloric acid (2.5mol/L).

3.6

sodium citrate buffer (pH 6.5 to 7.0). Weigh 294g in 1000mL beaker, sodium citrate, was added 900mL water soluble

Solution, adjusting the pH meter on with hydrochloric acid (3.5) and sodium hydroxide solution (3.3) pH value of 6.5 to 7.0 and transferred to 1000mL volumetric flask,

Diluted with water to the mark, mix and immediately stored in a plastic bottle.

3.7 Fluoride standard stock solution

Weigh 2.2101g superior grade pure sodium fluoride (120 °C drying to constant weight) in 250mL plastic bottle, plus

Dissolved in water transferred to 1000mL volumetric flask, dilute with water to volume, and mix immediately stored in a plastic bottle containing the solution 1mL

1mg fluorine.

3.7.1 Fluoride standard solution

Pipette 50.00mL fluoro standard stock solution (3.7) in 500mL volumetric flask, dilute to the mark,

Mix immediately stored in a plastic bottle, this solution 1mL containing 100µg fluorine.

3.7.2 Fluoride standard solution

Pipette 5.00mL fluoro standard stock solution (3.7) in 500mL volumetric flask, dilute to the mark,

Mix immediately stored in a plastic bottle, this solution 1mL containing 10µg fluorine.

3.8 bromocresol green indicator (1g/L of ethanol - water)

Weigh 0.1g bromocresol green dissolved in 20mL of ethanol, diluted with water to

100mL, and mix.

4.1

pH meter.

4.2

potential measuring instrument, precision 0.1mV.

4.3 fluoride ion selective electrode

fluoride ion detection limit should be less than 2.5 × 10-4mg/mL, the electrodes prior to use in 10-3mol/L […]