GB/T 1282-2013Chemical reagent -- Phosphoric acid (English PDF)

5.5 Chloride

Weigh 5g (3mL) of sample. Dilute to 20mL. Determine according to provisions

of GB/T 9729. Solution turbidity shall not be greater than standard turbidity

solution.

Preparation of standard turbidity solution takes chloride (Cl) standard solution

that contains following quantities. Perform same processing with sample

simultaneously.

Guaranteed reagent: 0.010mg; analytical reagent: 0.015mg; chemical pure:

0.025mg.

5.6 Sulfate

Weigh 5g (3mL) of sample. Dilute to 50mL. Take 10mL (5mL for chemical pure).

Dilute to 20mL. Add 0.5mL of hydrochloric acid solution (20%). Determine

according to provisions of GB/T 9728. Solution turbidity shall not be greater

than standard turbidity solution.

Preparation of standard turbidity solution takes sulfate (SO4) standard solution

that contains following quantities. Dilute to 20mL. Perform same processing

with same volume of sample solution simultaneously.

Guaranteed reagent: 0.01mg; analytical reagent: 0.03mg; chemical pure:

0.05mg.

5.7 Nitrate

Weigh 5g (3mL) of sample. Dilute to 10mL. Add 1mL of sodium chloride solution

(100g/L) and 1mL of indigo sodium disulphonate solution

[c(C16H8N2Na2O8S2)=0.001 mol/L]. While shaking, within 10s~15s, add 10mL

of sulfuric acid. Place for 10min. Blue of solution shall not be lighter than

standard colorimetric solution.

Preparation of standard colorimetric solution takes nitrate (NO3) standard

solution that contains following quantities. Perform same processing with

sample simultaneously.

Guaranteed reagent: 0.015mg; analytical reagent, chemical pure: 0.025mg.

5.8 Arsenic

5.8.1 Silver diethyldithiocarbamate method (arbitration method)

Weigh 4g (2.4mL) of sample. Dilute to 30mL. Inject into arsenic bottle.

Determine according to provisions of 4.2 in GB/T 610-2008. Purple red of

absorbent shall not be darker than standard colorimetric solution.

5.10.1.3 Preparation of test solution

See Annex A for pressurized ion exchange device. Ion exchange column is

loaded with strong acid cation exchange resin of which particle diameter is

0.04mm~0.08mm, and exchange capacity is 4mmol/g~5mmol/g. When

exchanged, flow rate is controlled at 1.0mL/min ~ 1.5mL/min.

Weigh 10g (6mL) of sample. Place in a 25mL volumetric flask. Dilute to scale.

Mix well. Open exchanger rubber plug. Inject 5mL of sample into exchanger.

Tighten rubber plug. Pressurize exchanger (less than 0.1MPa). Phosphoric acid

matrix flows out from lower end of exchanger and is discarded. Open exchanger

rubber plug. Add 5mL of water. Re-pressurize remaining sample in washing

exchanger and discard it.

Open exchanger rubber plug. Add 5mL of hydrochloric acid solution (10%).

Tighten rubber plug. Pressurize exchanger (less than 0.1MPa). Receive eluent

in a cleaned container. Add 5mL of water into exchanger. Pressurize washing

exchanger. Combine washing solution and eluent, as test solution.

5.10.1.4 Determination methods

5.10.1.4.1 Sodium

Take 1mL of test solution. Dilute to 250mL. Determine according to provisions

of 7.2.1 in GB/T 9723-2007. Calculate result according to provisions of 7.2.3.

5.10.1.4.2 Potassium, zinc

Take 1mL of test solution. Dilute to 10mL. Respectively determine according to

provisions of 7.2.1 in GB/T 9723-2007. Calculate result according to provisions

of 7.2.3.

5.10.1.4.3 Manganese, lead

Take test solution. Respectively determine according to provisions of 7.2.1 in

GB/T 9723-2007. Calculate result according to provisions of 7.2.3.

5.10.1.4.4 Nickel, copper, cadmium

Take 4mL of test solution. Dilute to 10mL. Respectively determine according to

provisions of 7.2.1 in GB/T 9723-2007. Calculate result according to provisions

of 7.2.3.

5.10.2 Inductively coupled plasma atomic emission spectrometry

5.10.2.1 Reagent, material and apparatus

In accordance with provisions of Clause 5, Clause 6 in GB/T 23942-2009.

{c[Ce(SO4)2]=0.1mol/L} and 10mL of silver sulfate solution (10g/L). Add 40mL

of water. Boil 15min. Cool. Dilute to original volume. Add 2 drops of 1,10-

phenanthroline-ferrous iron indicator solution. Use ammonium ferrous sulfate

standard titration solution {c[(NH4)2Fe(SO4)2]=0.1mol/L} to titrate till solution is

red. Carry out blank test at the same time.

Calculate mass fraction (w2) of reducing substance (in H3PO3) according to

formula (2):

Where,

V1 - Value of volume of ammonium ferrous sulfate standard titration solution

consumed by blank test, in milliliters (mL);

V2 - Value of volume of ammonium ferrous sulfate standard titration solution, in

milliliters (mL);

c - Accurate value of concentration of ammonium ferrous sulfate standard

titration solution, in Moore per liter (mol/L);

M - Value of molar mass of phosphorous, in grams per Moore (g/mol) [M

(1/2H3PO3)=41.00];

m - Value of sample mass, in grams (g).