GOST 22518.3-77
GOST 22518.3−77 Lead of high purity. Colorimetric method for the determination of mercury (with Amendments No. 1, 2, 3)
GOST 22518.3−77
Group B59
STATE STANDARD OF THE USSR
LEAD OF HIGH PURITY
Colorimetric method for determination of mercury
Lead of high purity. Colorimetric method for the determination of mercury
AXTU 1709
Date of introduction 1978−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
DEVELOPERS
HP Garcin, L. K. Larina
2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
The designation of the reference document referenced |
Paragraph number section |
GOST 3118−77 |
Sec. 2 |
GOST 3760−79 |
Sec. 2 |
GOST 4204−77 |
Sec. 2 |
GOST 4461−77 |
Sec. 2 |
GOST 4520−78 |
Sec. 2 |
GOST 6691−77 |
Sec. 2 |
GOST 6709−72 |
Sec. 2 |
GOST 20288−74 |
Sec. 2 |
GOST 22518.1−77 |
1a.1 |
THAT 6−09−07−1684−89 |
Sec. 2 |
5. The expiration time limit is removed by the Resolution of Gosstandart from 08.04.92 377
6. The re-release (Dec 1996) Amendments No. 1, 2, 3, approved in January 1983, June 1987, April 1992 (IUS 5−83, 9−87, 7−92)
This standard establishes the colorimetric method for the determination of mass fraction of mercury in lead of high purity grades S0000, S000 and S00 in the range from 8·10to 1·10%.
The method is based on determination of mercury by reaction with dithizone carried out in 0.5 mol/DMnitric acid solution.
(Changed edition, Rev. N 1, 3).
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 22518.1.
(Changed edition, Rev. N 2).
1a. SAFETY REQUIREMENTS
1A.1. Safety requirements — according to GOST 22518.1.
Sec. 1A. (Added, Rev. N 1).
2. APPARATUS, REAGENTS AND SOLUTIONS
Nitric acid according to GOST 4461, purified by distillation in quartz apparatus, diluted 1:3, and the solution of 0.5 mol/DMcooked on the double-distilled water.
Hydrochloric acid according to GOST 3118, purified by distillation, a solution of 0.5 mol/DM.
Sulfuric acid according to GOST 4204, and a solution with a concentration of 50 g/DM.
Urea according to GOST 6691, h.d. a.
Ammonia water according to GOST 3760.
Dicison on the other 6−09−07−1684−89, h. e. a., cleaned; prepared as follows: 1−2 g of dithizone placed in a separating funnel with a capacity of 1 DM, add 200−300 cmof chloroform the funnel and the contents shaken to dissolve ditizona. Then add 300−400 cmof water and 3−5 cmof ammonia with a density of 0.91 g/cm. Ditson extracted into the aqueous phase. The extraction is repeated several times. The combined alkaline extracts bright orange color is transferred to a separatory funnel and washed several times with carbon tetrachloride. The solution is acidified by sulfuric acid solution with a concentration of 50 g/DMto slightly acidic environment. Flakes ditizona dark green washed by decantation until neutral environment and was filtered through a glass crucible with a porous bottom. Purified ditson dried and transferred to BUCs. It serves for the preparation of a backup solution.
Stock solution of dithizone in carbon tetrachloride with a concentration of 0.2 g/l; prepared as follows: 20 mg of purified dithizone dissolved in 100 cmof carbon tetrachloride.
The working solution of dithizone with a concentration of 0.005 g/DM; prepared by diluting a backup solution of carbon tetrachloride in 40 times.
Mercury nitrate according to GOST 4520, h. e. a., stock solution; prepared as follows: 0,1663 g of nitrate of mercury dissolved in water, acidified by a solution of nitric acid and the volume was adjusted in a volumetric flask to 1 DM.
1 cmof the solution contains 100 micrograms of mercury.
A standard solution of nitrate of mercury; prepared on the day of use by dilution of a backup solution 100 times with a solution of 0.5 mol/DMnitric acid.
Carbon tetrachloride according to GOST 20288, h. e. a., distilled. Collect the fraction with a boiling point of 76.5 °C.
Bidistilled water obtained by distillation of the water according to GOST 6709 in a quartz apparatus in the presence of a few drops of permanganate and alkali.
(Changed edition, Rev. N 1, 2).
3. ANALYSIS
3.1. 5 g of finely chopped lead is placed in a beaker with a capacity of 250 cmand are dissolved in 40 cmof nitric acid, diluted 1:3.
The solution was evaporated to a volume of 3−4 cm. In the end the solution was evaporated in a water bath.
To the residue add 15−20 cmof water, the solution was heated to dissolve the nitrate of lead, add about 50 mg of urea to destroy the influence of nitrogen oxides on decison and heated to boiling. The cooled solution was transferred to a separatory funnel with a capacity of 50 cmand diluted with water to a volume of 25−30 cm. Add one intake of 0.4−2 cmof a solution of dithizone, funnel vigorously shaken for 1 min and the supernatant carbon tetrachloride having mixed yellow-green in color, is poured into another separatory funnel with a capacity of 25 cm. Pour 5−10 cmof a solution of 0.5 mol/DMof hydrochloric acid and shake the funnel several times.
In another separatory funnel is introduced a solution of 0.5 mol/DMof hydrochloric acid and dithizon in the same amounts that are contained in the funnel with the test solution, and add from microburette standard solution of nitrate of mercury to the adjustment of coloring layers of carbon tetrachloride.
At the same time conduct test experience for the presence of mercury in the reagents, carrying it through all the stages.
The lead does not preclude the definition. The impact of possible admixture of silver is removed by washing of the extract dithizonate solution of 0.5 mol/DMof hydrochloric acid.
(Changed edition, Rev. N 3).
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of mercury in lead of high purity () in percent is calculated by the formula
,
where — the volume of a standard solution of mercury consumed for the adjustment of color, cm;
the titer of the solution of mercury, g/cm;
— its weight of lead,
For the results analysis be the arithmetic mean of results of three parallel measurements.
(Changed edition, Rev. N 1, 3).
4.2. The differences of maximal and minimal values of the results of three parallel measurements () and the results of two tests () with 0.95 confidence probability does not exceed the permissible differences given in table.
Mass fraction of mercury, % |
The discrepancy between the results of parallel measurements , % |
The discrepancy between the results of two tests , % |
8·10 |
8·10 |
9·10 |
2·10 |
2·10 |
2·10 |
4·10 |
4·10 |
4·10 |
8·10 |
7·10 |
9·10 |
2·10 |
2·10 |
2·10 |
Permitted discrepancies for the intermediate mass fraction of mercury is calculated by the formula
;,
where is the arithmetic mean of the results of parallel measurements;
— the average of the two results of the analysis.
(Changed edition, Rev. N 3).