1 Scope
This standard specifies the determination methods for sodium chloride, lead, total arsenic, cadmium, total mercury, barium, potassium chloride, potassium ferricyanide and iodine in table salt.
This standard is applicable to determination of table salt index.
2 Determination of Sodium Chloride
2.1 Determination of moisture content
Operate according to the direct drying method in GB 5009.3 and set the drying temperature to 140℃ ±2 ℃; dry until the difference between masses weighed continuously does not exceed 5mg, i.e., constant weight.
2.2 Determination of chlorine ion
2.2.1 Principle
After the sample is dissolved, take the potassium chromate as indicator and titrate with standard silver nitrate titration solution so as to determine the chlorine ion content.
2.2.2 Reagents and materials
Unless otherwise specified, analytically-pure reagents and Grade III water (defined in GB/T 6682) are adopted for the purposes of this method.
2.2.2.1 Reagents
2.2.2.1.1 Silver nitrate.
2.2.2.1.2 Potassium chromate.
2.2.2.2 Preparation of reagents
2.2.2.2.1 Standard silver nitrate titration solution (0.1mol/L).
2.2.2.2.2 Potassium chromate indicator: weigh 10g of potassium chromate and dissolve it into 100mL of water, dropwise add silver nitrate solution while stirring until reddish brown precipitate appears, and then filter the solution.
Foreword i
1 Scope
2 Determination of Sodium Chloride
3 Determination of Lead
4 Determination of Total Arsenic
5 Determination of Cadmium
6 Determination of Total Mercury
7 Determination of Barium
8 Determination of Potassium Chloride
9 Determination of Potassium Ferricyanide (Ferrous Sulfate Method)
10 Determination of Iodine (Oxidation-reduction Titration)
