GB/T 1287-1994 in English

《GB/T 1287-1994化学试剂 六水合硫酸镍（硫酸镍）》由TC63（全国化学标准化技术委员会）归口，主管部门为中国石油和化学工业联合会。

ChinaStandards.net is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.

The reagent is green crystal and soluble in water.
Molecular formula: NiSO4·6H2O
Relative molecular mass: 262.85 (as per the international relative atomic mass in 1991)
1 Subject content and applicable scope
This standard specifies the technical requirements, test methods, inspection rules, packaging and marking of nickel sulfate hexahydrate reagent.
This standard is applicable to the inspection of nickel sulfate hexahydrate reagent.
2 Normative references
GB/T 601 Chemical reagent—Preparations of standard volumetric solutions
GB/T 602 Chemical reagent—Preparations of standard solutions for impurity
GB/T 603 Chemical reagent—Preparations of reagent solutions for use in test methods
GB/T 619 Chemical reagent—Regulations for sampling and acceptance
GB/T 3914 Chemical reagents—The general rules of anodic stripping voltammetry
GB/T 6682 Water for analytical laboratory use—Specification and test methods
GB/T 9723 Chemical reagent—General rule for flame atomic absorption spectrometric analysis
GB/T 9738 Chemical reagent—General method for the determination of water insoluble matter
HG 3-119 Chemical reagent—Packaging and marking

3 Technical requirements
3.1 Content (%) of nickel sulfate hexahydrate (NiSO4·6H2O):
Guaranteed reagent ≥99.0;
Analytical reagent ≥98.5;
Chemically pure ≥98.0.
3.2 Maximum content of impurities:
%
Element Guaranteed reagent Analytical reagent Chemically pure
Water insoluble matter 0.005 0.01 0.02
Chloride (Cl) 0.001 0.001 0.005
Nitrate (NO3) 0.003 0.003 0.02
Sodium (Na) 0.01 0.02 0.05
Calcium (Ca) 0.005 0.02 0.1
Iron (Fe) 0.0005 0.001 0.005
Cobalt (Co) 0.002 0.01 0.05
Copper (Cu) 0.001 0.002 0.005
Zinc (Zn) 0.002 0.01 0.05
Lead (Pb) 0.001 0.002 0.005

4 Test method
In this test method, unless otherwise specified, the standard titration solutions, impurity standard solutions, preparations and products shall be prepared in accordance with the provisions of GB/T 601, GB/T 602, and GB/T 603; the water for test shall meet the specification of Grade 3 required by GB/T 6682.
4.1 Determination of nickel sulfate hexahydrate (NiSO4·6H2O)
Weigh, to the nearest 0.000 1 g, 0.5 g of the sample and dissolve in 70 mL of water, add 10 mL of ammonia-ammonium chloride buffer solution A (pH≈10) and 0.2 g of ammonium violet urea mixed indicator, shake well, and titrate it with ethylenediaminetetraacetic acid disodium salt (EDTA) standard titration solution [c (EDTA) = 0.05 mol/L] until the solution turns blue-purple.
The content shall be calculated by using the following formula:

where, X——the mass percentage of nickel sulfate hexahydrate, %;
V——the volume of EDTA standard titration solution, mL;
c——the actual concentration of EDTA standard titration solution, mol/L;
0.2629——the mass of nickel sulfate hexahydrate equivalent to 1.00 mL of EDTA standard titration solution [c (EDTA) = 1.000 mol/L], g.
m——the mass of sample, g.
4.2 Determination of impurities
The sample must be weighed to the nearest 0.01 g.
4.2.1 Water insoluble matter
Dissolve 25 g of the sample in 100 mL of boiling water, cool it to room temperature, and filter it with No.4 glass filter crucible with constant weight at 105 ± 2 °C; wash the filter residue with hot water until the water is colorless, and dry it in an electric oven at 105 ± 2 °C to constant weight. The results shall be calculated in accordance with the provisions of Clause 7 in GB/T 9738.
4.2.2 Chloride
4.2.2.1 Preparation of chloride-free nickel sulfate hexahydrate solution
Dissolve 5 g of the sample in 100 mL of water, add 10 mL of nitric acid solution (25%) and 5 mL of silver nitrate solution (17 g/L), then dilute it to 125 ml, shake well, stand for 12 ~ 18 h, and filter it.
4.2.2.2 Determination method
Dissolve 1 g of the sample in 20 mL of water (filter if necessary), add 2 mL of nitric acid solution (25%) and 1 mL of silver nitrate solution (17 g/L), then dilute it to 25 mL, shake well, and stand for 10 min. The turbidity of the solution shall not be more intense than that in the standard.
The standard takes 25 mL of chloride-free nickel sulfate hexahydrate solution and impurity standard solution containing the following amount of chloride:

1 Subject content and applicable scope
2 Normative references
3 Technical requirements
4 Test method
5 Inspection rules
6 Packaging and marking