GOST 19251.3-79

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  ГОСТ 19251.3-79

GOST 19251.3−79 Zinc. Method for the determination of copper (with Amendments No. 1, 2, 3)

GOST 19251.3−79

Group B59

STATE STANDARD OF THE USSR

ZINC

Method for determination of copper

Zinc.
Method of copper determination

AXTU 1709

Date of introduction 1980−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

DEVELOPERS

V. I. Lysenko, L. I. Maksay, R. D. Cohen, V. A. Kolesnikov, N. Romanenko, R. A. Pestova

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 09.08.79 N 3077

3. Change No. 3 adopted by the Interstate Council for standardization, Metrology and certification (Protocol № 7 from 26.04.95)

The adoption voted:

4. The frequency of inspection 5 years

5. INSTEAD 19251.3 GOST-73

6. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

7. Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

8. REPRINT (February 1998) with Amendments No. 1, 2, 3, approved in October 1984, April 1989, June 1996 (ICS 1−85, 7−89, 9−96)


This standard specifies the photometric (with mass fraction of copper from 0.0005 to 0.08%) method of determination of copper.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis and security requirements — according to GOST 19251.0.

(Changed edition, Rev. N 1).

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF COPPER

2.1. The essence of the method

The method is based on dissolving the sample in nitric acid and photometric determination of the copper content with diethyldithiocarbamate lead in the region of wavelengths 430−455 nm or cuprizone at a wavelength of 600 nm.

The sensitivity of the method for determination of copper by diethyldithiocarbamate lead — 2 ág in a volume of 25 cm, the sensitivity of the determination of copper with cuprizone — 10 µg in a volume of 50 cm.

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter of any kind for measurements in the visible region of the spectrum.

Nitric acid according to GOST 4461, diluted 1:1.

Hydrochloric acid according to GOST 3118.

Ammonia water according to GOST 3760.

Ammonium citrate, solution 100 g/DM.

Hydrogen peroxide according to GOST 10929.

Ethyl alcohol according to GOST 18300, diluted 1:1.

Lead acetate according to GOST 1027.

Diethyldithiocarbamate sodium GOST 8864, a solution of 10 g/DM.

A solution of diethyldithiocarbamate lead: 0.2 g of lead acetate dissolved in 20 cmof water, add 2cmof a solution of sodium diethyldithiocarbamate and leave for 30 minutes Transfer the solution into separatory funnel with a capacity of 250−300 cm, add 10 cmof chloroform (carbon tetrachloride) and shake the contents of the funnel for 1 min. Painted the extract discarded. In the funnel add 1 cmof a solution of sodium diethyldithiocarbamate, 10 cmof chloroform (carbon tetrachloride) and shaken for 1 min. If the extract is colored yellow by traces of copper purification from copper is repeated to produce a colorless extract. To the aqueous solution in the funnel add 20 cmof a solution of sodium diethyldithiocarbamate, and the precipitate of lead diethyldithiocarbamate dissolved in chloroform (carbon tetrachloride), adding the final portions to 150 cm. After settling, the extract is decanted into a volumetric flask with a capacity of 1 DM, adjusted to the mark with chloroform, (carbon tetrachloride) and stirred. The solution is steady for a long time if kept in a flask stoppered and in the dark.

Note. Permitted removal of a solution of acetate of lead with potassium cyanide.


Chloroform (trichlormethane, carbon tetrachloride according to GOST 20288).

Cuprizone, a 0.5% solution: 0.5 g of the reagent is dissolved in 20 cmof hot ethyl alcohol diluted 1:1, cooled, made up to a volume of 100 cmalcohol diluted 1:1, and stirred.

Copper of mark M0 GOST 859*.
_______________
* On the territory of the Russian Federation GOST 859−2001. — Note the CODE.

Standard solutions of copper.

Solution a: a sample of copper with a mass 0,1000 g dissolved in 20 cmof nitric acid, diluted 1:1, heated to remove oxides of nitrogen, cooled, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

1 cmof solution A contains 0.1 mg of copper.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof a solution contains 0.01 mg of copper.

Solution: 10 cmsolution And placed in a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.004 mg of copper.

(Changed edition, Rev. N 2,

3).

2.3. The analysis of lead diethyldithiocarbamate

2.3.1. Suspension zinc weight 1,0000 g is placed in a conical flask with a capacity of 250 cm, was dissolved with heating in 10 cmof nitric acid. Pour 50 cmof water, boil to remove oxides of nitrogen, and cooled. The solution was transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix. Aliquot part of the solution (table.1) is placed in a separating funnel with a capacity of 100 cm, was diluted to 50 cmof water (mark on the separating funnel). Add from a burette 25 cmof a solution of lead diethyldithiocarbamate, and shake 1 min. the Supernatant extract is decanted into a dry flask with a capacity of 50 cm, cover with lid and allow to settle for 10−20 min.

Optical density of the solution measured on a spectrophotometer at a wavelength of 436 nm or photoelectrocolorimeter, in the region of wavelengths 430−455 nm in the corresponding cell (table.1).

Table 1

Solution comparison in the measurement of optical density is chloroform (carbon tetrachloride).

(Changed edition, Rev. N 2, 3).

2.3.2. For construction of calibration graphs in six separating funnels pour 50 cmof water, add 2−3 drops of nitric acid, previously boiled, measure out 0; 0,5; 1,0; 2,0; 3,0 and 4,0 cmstandard solution, which corresponds to 0, 2, 4, 8, 12 and 16 mg of copper (series I).

Eight separatory funnels pour 50 cmof water, add 2−3 drops of nitric acid, previously boiled, measure out 0; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 and 4.0 cmstandard solution B, which corresponds to 0; 5; 10; 15; 20; 25; 30 and 40 mcg copper (series II).

From burette is added in separating funnel for 25 cmof lead diethyldithiocarbamate and shaken for 1 min. the Supernatant extract is decanted into a dry flask with a capacity of 50 cm, cover with lid and allow to settle for 10−20 min.

The optical density of the solutions measured as described in section 2.3.1, in a ditch with the thickness of the light absorbing layer of 50 mm for solutions I series and 20 mm — II series.

According to the obtained values of optical density of the solutions and their corresponding mass fractions of copper to build the calibration graphs.

(Changed edition, Rev. N 2, 3).

2.4. The analysis cuprizone

2.4.1. Suspension zinc weight 1,0000 g is placed in a conical flask with a capacity of 250 cm, and dissolved in 10 cmof hydrochloric acid. After dissolution of the sample add 10 drops of hydrogen peroxide and the solution is evaporated to a syrupy condition, avoiding the allocation of zinc salts. The solution is diluted with a small amount of water and cooled. For the analysis we take the entire solution or part of it after dilution in accordance with the table.2.

Table 2

Part of the solution or the entire solution is placed in a volumetric flask with a capacity of 50 cm, carefully pour the ammonia until the appearance of the precipitate of zinc hydroxide which is then dissolved by adding 1−2 drops of hydrochloric acid. Pour 5 cmof a solution of ammonium citrate and ammonia to pH 9. The solution is cooled and added 5 cmof the solution cuprizone. After 10 minutes, bring the solution to the mark with water, mix and leave for 1 hour

The optical density of solutions measured at a wavelength of 600 nm in the corresponding cell.

Solution comparison in the measurement of optical density is the solution of the reference experiment.

(Changed edition, Rev. N 1, 2, 3).

2.4.2. To build a calibration curve in seven of the eight volumetric flasks with a capacity of 50 cmmeasure 1; 2; 4; 6; 8; 10 and 12.5 cmstandard solution B, which corresponds to 10; 20; 40; 60; 80; 100 and 125 mcg of copper. In each flask pour 5 cmof a solution of citrate of ammonium and further analysis is carried out as specified in clause 2.4.1.

According to the obtained values of optical densities and their corresponding grades of copper to build the calibration graph.

2.5. Processing of the results

2.5.1. Mass fraction of copper (), %, is calculated by the formula

,

where is the mass of copper in the sample solution found by the calibration schedule, mcg;

 — the weight of the portion of the sample contained in the selected part of the solution,

2.5.2. The absolute values of the differences between the results of two parallel measurements (rate of convergence) and the results of the two tests (index of reproducibility) with the confidence coefficient =0.95 does not exceed values of allowable differences specified in table.3.

Table 3

(Changed edition, Rev. N 2).

Section 3. (Deleted, Rev. N 3).