Some standard content:
National Standard of the People's Republic of China
Working chemical
Calcium carbonate
This reagent is white powder, insoluble in water. Molecular formula: CaCO3
Relative molecular mass: 100.09 (according to the international atomic weight in 1987) Subject content and scope of application
GB12596.. 90
This standard specifies the technical requirements, test methods, inspection rules, packaging and marking of working standard reagent (volume) calcium carbonate. This standard is applicable to the inspection of working standard reagent (volume) calcium carbonate with a content of 99.95% to 100.05%. 2 Reference standards
GB 619
Chemical reagents-Preparation of standard solutions for titration analysis (volume analysis) Chemical reagents-Preparation of standard solutions for determination of impurities Chemical reagents
Chemical reagents
Chemical reagents
GB6682
Preparation of preparations and products used in test methods-General method for determination of total nitrogen
Sampling and acceptance rules
Specifications for laboratory water
GB9723·Chemical reagents-General rules for flame atomic absorption spectrometry GB9728
GB9729
GB 9739
GB 10738
Chemical reagents
General method for determination of sulfate
Chemical reagents
General method for determination of chloride
Chemical reagents
General method for determination of iron
General rule for weighing titration of working standard reagents (volume) HG3—119 Packaging and marking of chemical reagents
Preparation and determination method of clarity standard of chemical reagents HG 3--- 1168
3 Technical requirements
3.1 Calcium carbonate (Caco) content, %: 99.95~100.05. 3.2 Maximum impurity content, %:
Approved by the State Administration of Technical Supervision on December 18, 1990654
Implemented on December 1, 1991
Clarity test, No.
Loss on drying
Alkalinity (as OH-), mmol/100 g
Chloride (CI)
Sulfate (SO,)
Total nitrogen (N)
Magnesium (Mg)
Iron (Fe)
Heavy metal (as Pb)
Test method
GB 12596—90
Working standard (capacity)
The standard solution for titration analysis, standard solution for impurity determination and the preparations and products used in this test method shall be prepared in accordance with the provisions of GB601, GB602 and GB603. The experimental water shall meet the specifications of Grade 3 water in GB6682. 4.1 Determination of calcium carbonate (CaCOs) content
Weigh 0.15g of the sample after the drying loss determination to an accuracy of 0.00001g, place it in a reaction bottle, add 0.6mL of hydrochloric acid solution (20%) to dissolve, add 100mL of water, and titrate with disodium ethylenediaminetetraacetic acid standard bath solution [c (EDTA) = 0.050mol/kg) in accordance with the provisions of GB10738. When the end point is near, add 5 mL of magnesium ethylenediaminetetraacetic acid solution, 10 mL of ammonia-ammonium chloride buffer solution A (pH = 10) and 3 drops of chrome black T indicator solution (5 g/L), and continue titrating until the solution changes from purple to pure blue. At the same time, perform a blank test. Disodium ethylenediaminetetraacetic acid standard solution [c (EDTA) = 0.050 mol/kg) is prepared by weight method using the first standard reagent (volume) disodium ethylenediaminetetraacetic acid [see Appendix A (Supplement)], and the relative error of its concentration shall not exceed 5×10-%. The content of calcium carbonate (CaCO3) is calculated according to formula (1): (ml - m2)c X 0. 100 09
Wherein: X
Percentage of calcium carbonate, %;
m,--mass of disodium ethylenediaminetetraacetic acid standard solution, g; m2--mass of disodium ethylenediaminetetraacetic acid standard solution in blank test, g; concentration of disodium ethylenediaminetetraacetic acid standard solution, mol/kg; 0. 100 09-
(1)
Mass of calcium carbonate in grams equivalent to 1.0000g disodium ethylenediaminetetraacetic acid standard solution Cc (EDTA) = 1.0000mol/kg];
Mass of the sample, nom.
Note: ① In formula (1), ml and m2ms should be corrected for buoyancy according to the provisions of Appendix B (Supplement) of GB10738 before being substituted into the formula. ②The density of calcium carbonate is 2.93g/cm.
4.2 Determination of impurities
The sample must be weighed accurately to 0.01g.
4.2.1 Clarity test
Weigh 10g of the sample, dissolve it in 10mL of water and 45mL of hydrochloric acid solution (20%), and dilute to 100mL. Its turbidity shall not be greater than the clarity standard No. 5 specified in HG 3-~1168. 4.2.2 Loss on drying
Weigh 2g of the sample, accurate to 0.0001g, place it in a weighing bottle that has been constant weight at 110±2℃, and dry it in an electric oven at 110±2℃ to constant weight. After the constant weight is retained, the sample is used for content determination. The drying loss is calculated according to formula (2):
Where: x
… drying loss, %;
The mass of the sample before drying, g;
m2—The mass of the sample after drying to constant weight, g. 4.2.3 Alkalinity
GB12596
. (2)
Weigh 3g of the sample, add 30mL of carbon dioxide-free water, warm, shake for 10min, cool, and filter. Take 20mL of the filtrate, add 2 drops of phenolic acid indicator solution (10g/L). If the solution is red, titrate with hydrochloric acid to titrate the standard solution for analysis (c(HC1)=0.1mol/L) until the solution is colorless. Alkalinity is calculated according to formula (3):
Alkalinity=1.5××100
Amount of standard solution for hydrochloric acid titration analysis, mL; V—--
Concentration of standard solution for hydrochloric acid titration analysis, mol/L; m-—mass of sample, g.
4.2.4 Chloride
(3)
Weigh 1g of sample, dissolve in 10mL of water and 6mL of nitric acid solution (25%), dilute to 20mL, and measure according to the provisions of GB9729. The turbidity shall not be greater than the standard.
The standard is to take a standard solution for impurity determination containing 0.01mg of chloride (C1), dilute to 20mL, and treat it in the same way as the sample solution of the same volume.
4.2.5 Sulfate
Weigh 0.5g sample, add 5mL water, add hydrochloric acid solution (20%) until the sample is dissolved, dilute to 100mL, take 20mL, and measure according to the provisions of GB9728. The turbidity shall not be greater than the standard. The standard is to take the impurity determination standard solution containing 0.01mg sulfate (SO.), dilute to 20mL, and treat it in the same way as the sample solution of the same volume.
4.2.6 Total nitrogen
Weigh 1g sample, add 5mL water, add hydrochloric acid solution (20%) until the sample is dissolved, and dilute to 20mL. According to the provisions of GB609, the yellow color shall not be darker than the standard.
The standard is to take the impurity determination standard solution containing 0.10mg nitrogen (N), dilute to 20mL, and treat it in the same way as the sample solution of the same volume.
Measured in accordance with the provisions of GB9723, where:
4.2.7.1 Instrument conditions
Light source: magnesium hollow cathode lamp;
Wavelength: 285.2nm;
Flame: acetylene-air.
4.2.7.2 Determination method
Weigh 0.5g sample, add 5mL water, drop hydrochloric acid solution (20%) until the sample is dissolved, dilute to 100mL, take 4mL, a total of four portions, and measure according to the provisions of Article 6.2.2 of GB9723. www.bzxz.net
Weigh 1g sample, dissolve in 5mL water and 5mL hydrochloric acid solution (20%), dilute to 15mL, adjust the solution pH to 2 with ammonia solution (10%), and measure according to the provisions of GB9739. The red color should not be deeper than the standard. The standard is to take a standard solution containing 0.01mg iron (Fe) for impurity determination, add 0.1mL hydrochloric acid solution (20%), dilute to 15mL, and treat it in the same way as the sample solution of the same volume. 656
4.2.9 Heavy metals
GB12596—90
Weigh 2g of the sample, dissolve it in 5mL water and 10mL hydrochloric acid solution (20%), and evaporate it to dryness on a water bath. Dissolve the residue in water and dilute to 40mL. Take 30mL, add 0.2mL acetic acid solution (30%) and 10mL newly prepared saturated hydrogen sulfide water, shake well, let stand for 10 minutes, the dark color should not be darker than the standard.
The standard is to take the impurity determination standard solution containing 0.01mg lead (Pb) and the remaining 10mL sample solution, dilute to 30mL, and treat it in the same way as the sample solution of the same volume.
Inspection rules
Sampling and acceptance shall be carried out in accordance with the provisions of GB619. Packaging and marking
In accordance with the provisions of HG 3-119, among which:
Inner packaging form: G-2;
Outer packaging form: Use boxboard paper with a specification of 600g/m2 to make a box, and the outer layer is mounted with purple electro-optical paper. 657
GB12596---90
Appendix A
Preparation of reference solution
(Supplement)
The balance and magnetic code used in the preparation of reference solution are all third-level balances and second-level codes. The weighing method is the substitution method. The water used should be placed in a constant temperature room in advance, and its temperature is the same as that of the constant temperature room. A1 Drying of the first reference reagent (volume)
Dry the first reference reagent (volume) to constant weight under the specified conditions. Weighing of the sample
Calculate the required amount of the first reference reagent (volume) according to the concentration and mass of the reference solution to be prepared. Weigh the sample after constant weight in Article A1 according to the above calculated amount, and the mass of the sample shall be corrected for buoyancy according to the formula in Appendix B of GB10738.
A3 Dissolution of the sample
Put the sample weighed in item A2 in a beaker, add a small amount of water to dissolve it, and place it in a constant temperature room for 1 to 2 hours. A4 Preparation of the reference solution
Take a dry volumetric flask and weigh it. After weighing, transfer the solution obtained in item A3 to the volumetric flask, add water to a weight slightly less than the weight of the solution to be prepared, weigh it, add a small amount of water, continue to weigh it, repeat several times until the required weight is weighed, and mix it. The weight of the solution is corrected for buoyancy according to the formula in Appendix B of GB10738.
5 Calculation of the concentration of the reference solution
The concentration of the reference solution is calculated as follows:
×1000
Where: c-the concentration of the reference solution, mol/kg; ml-the mass of the first reference reagent (volume) after buoyancy correction, g; m2--the mass of the reference solution after buoyancy correction, g; M--the relative molecular mass of the first reference reagent (volume), g/mol. Additional Notes:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard was managed by Beijing Chemical Reagent Factory. This standard was drafted by Beijing Chemical Factory. The main drafters of this standard were Zhao Fenglan, Fan Yiming and Qiang Jinglin.
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