GOST 1367.5-83
Approved and put into effect
By the decree of Gosstandart of the USSR
December 16, 1983 N 6012
STATE STANDARD OF THE USSR
ANTIMONY
METHODS FOR DETERMINATION OF LEAD
Antimony. Methods for the determination of lead
GOST 1367.5−83
Group B59
AXTU 1709
Replace GOST 1367.5−76
Valid from January 1, 1985
before January 1, 1990
This standard sets the polarographic method for the determination of lead ranging from 0.02 to 1.0%, complexometrically and chromate methods for determination of lead from 0.5 to 5.0% antimony grades Su00, su0, SS1 and SS2.
(as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis and security requirements — according to GOST 1367.0−83.
2. POLAROGRAPHIC METHOD
The method is based on polarographically of lead in hydrochloric acid background. Antimony and tin, deformity, distilled in the form of bromides in the decomposition of the sample with bromatologicalacid.
2.1. Apparatus, reagents and solutions
Polarography with superimposed DC voltage with mercury electrodes (cathode mercury dripping, the cell with an external anode. In the anode space is filled with mercury and a saturated solution of potassium chloride) or polarography oscillographic-type-5122, or AC type PU-1.
Beakers, glass, laboratory for GOST 25336−82 with a capacity of 50, 100, 500 cm3.
Volumetric flasks according to GOST 1770−74 with a capacity of 50, 100 cm3 and 1 dm3.
Microburette with divisions according to GOST 1770−74 with a capacity of 5 cm3.
Nitric acid GOST 4461−77 and diluted 1:3.
Hydrochloric acid by the GOST 3118−77 and diluted 1:1, 1:3.
Acid bromide and hydrogen GOST 2062−77.
Ascorbic acid for NTD.
(as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
Potassium chloride on the other 6−09−5077−83, saturated solution.
(as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
Mercury metal in the NTD.
Lead according to GOST 3778−77, brand With1.
The solution of lead standard: a sample of lead with a mass of 1.0 g was placed in a beaker with a capacity of 500 cm3, poured 30 cm3 of nitric acid (1:3) and heated. After dissolution, the sample solution was evaporated to obtain a wet salts, add 15 cm3 of concentrated hydrochloric acid and again evaporated almost to dryness. The evaporation is repeated twice more, each time using 5 cm3 of hydrochloric acid (1:1). To the residue poured 250 cm3 of concentrated hydrochloric acid, heated, diluted with water, poured into a measuring flask with volume capacity of 1000 cm3, top up with water to the mark and mix.
1 cm3 of solution contains 1 mg lead.
2.2. Analysis
2.2.1. A portion of the antimony in weight 0.5 g brand Su00 or a mass of 0.2 g DM SS0, SS1, SS2 is placed in a beaker with a capacity of 100 cm3, poured 5 cm3 of concentrated nitric acid and evaporated to dryness. To the dry residue poured 100 cm3 bromatological acid and again evaporated to dryness. Processing bromatological acid is performed twice, adding each time 5 cm3 bromatological acid. The dry residue moistened with 10−15 drops of hydrochloric acid (1:1) and again evaporated to dryness. This operation is repeated two times.
To the dry residue poured 30 cm3 of hydrochloric acid (1:3) and heated 5 min until complete dissolution of salts. The resulting solution in the analysis of antimony brands Su00, su0 SU1 and poured into a volumetric flask with a capacity of 50 cm3 and the analysis of antimony stamps SS2 is poured into a measuring flask with a capacity of 100 cm3. Then the slurry is poured to the mark with hydrochloric acid (1:3), mixed well and allowed to settle. If the solution volume was 50 cm3, it is used whole, and of volume 100 cm3 is cast in a dry glass part of the solution (30−50 cm3), add 0.1 g of ascorbic acid and leave for 15−20 min.
The solution was then transferred into the cell, previously it was washed with the same solution, and polarographic lead at a potential of minus peak of 0.46 V. When operating the oscilloscope dripping period of mercury from the capillary 5 — 6 s, pulse delay 3 to 4 withthe feed speed of the voltage on the electrolytic cell of 0.25 — 0.58 In/s. Simultaneously with the analyzed samples off polarogram solution comparison of lead, prepared in the same way as the sample.
2.2.2. For the preparation of solutions comparison of lead in a volumetric flask with a capacity of 100 cm3, poured from microburette standard solution of lead in the amount of 0,1; 0,2; 0,5; 1,0; 2,0; 4,0; 6,0; 8,0; 10 cm3, which corresponds to 0,1; 0,2; 0,5; 1,0; 2,0; 4,0; 6,0; 8,0 and 10 mg of lead. The volume of the solutions was adjusted to the mark with hydrochloric acid (1:3) and stirred. Dry the glasses with a capacity of 50 cm3 cast of approximately 30 cm3 of solution, add 0.1 g of ascorbic acid and after 15 minutes remove polarogram.
Lead concentration in the solutions, respectively equal 1; 2; 5; 10; 20; 40; 60; 80; 100 mg/dm3.
2.3. Processing of the results
2.3.1. Mass fraction of lead (X) in percent is calculated by the formula
,
where is the wave height of solution of the sample, mm;
with — mass of lead in solution comparisons, mg/dm3;
V — the solution volume of the sample, cm3;
— the height of the wave solution comparison, mm;
m — mass of sample analyzed sample, g.
2.3.2. The difference between the two results of parallel measurements and the difference of two analysis results with a confidence probability P=0.95 does not exceed the allowable absolute differences of precision and reproducibilityare shown in table. 1.
Table 1
──────────────────────────┬──────────────────────────────────────
Mass fraction of lead, % │allowable Absolute differences, %
├────────────────┬─────────────────────
│ convergence │ reproducibility
──────────────────────────┼────────────────┼─────────────────────
From 0.020 to 0.040 incl. │0,005 │0,006
SV. 0,040 «0,100» │0,010 │0,012
«0,100» 0,200 «│0,02 │0,024
«0,20» 0,40 «│0,03 │0,04
«0,40» 1,00 «│0,05 │0,06
(2.3.2 as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
3. CHELATOMETRIC METHOD
The method is based on the isolation of lead as sulphate and titration with Trilon B in acetate buffer solution at pH 5 — 6 in the presence of an indicator kylinalove orange. Antimony, deformity, distilled in the form of bromides in the decomposition of the sample with bromine or bromatologicalacid.
3.1. Apparatus, reagents and solutions
Beakers according to GOST 1770−74 with a capacity of 50, 100 cm3.
Flask wide mouth lab glass according to GOST 23932−79 with a capacity of 250 cm3.
(as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
Beakers, glass, laboratory for GOST 25336−82 capacity of 500 cm3.
Volumetric flasks according to GOST 1770−74 with a capacity of 1 dm3.
Pipette with divisions according to GOST 20292−74 with a capacity of 2, 5, 10 cm3.
Burettes according to GOST 20292−74 with a capacity of 25 cm3.
Nitric acid GOST 4461−77 diluted 1:3.
Hydrochloric acid by the GOST 3118−77 and diluted 1:1.
Sulfuric acid GOST 4204−77, diluted 1:1, 1:6, 1:20.
Acid bromide and hydrogen GOST 2062−77.
Bromine according to GOST 4109−79.
Potassium nitrate according to GOST 4217−77.
Selenology orange: 0.5 g kylinalove orange mixed in a porcelain mortar with 50 g of potassium nitrate; serves as an indicator during the titration.
Ammonium acetate according to GOST 3117−78, solution: 250 g of ammonium acetate dissolved in water, poured 8 cm3 of concentrated hydrochloric acid and dilute with water to 1 dm3. The solution should have a pH 5,7−6,0, check on universal indicator paper.
Lead according to GOST 3778−77 brand With1.
The solution of lead standard: a sample of lead with a mass of 1.0 g was placed in a beaker with a capacity of 500 cm3, poured 30 cm3 of nitric acid (1:3) and heated. The solution is diluted with water, poured into a volumetric flask with a capacity of 500 cm3, made up to the mark with water and mix.
1 cm3 of solution contains 2 mg of lead.
Salt disodium ethylenediaminetetraacetic acid (Trilon B) according to GOST 10652−73, 0.01 mol/dm3 solution: 3,7225 g Trilon B dissolved in water, filtered in a volumetric flask with a capacity of 1 dm3, made up to the mark with water and mix.
3.2. The titer determination Trilon B
To install the titer of 0.01 mol/dm3 solution of Trilon B pipetted 10 cm3 of a standard solution of lead in a wide-mouthed flask with a capacity of 250−300 cm3 and poured 5 cm3 of concentrated sulphuric acid. The contents of the flask evaporated to dryness, cooled and poured 20 cm3 of sulphuric acid (1:6). Close the flask watch glass, boiled for 1 min, cooled and left for 1 h in cold running water.
The precipitate of lead sulphate is filtered off through the ball of filtrowanie mass, washed the precipitate and the flask 2−3 times with cold sulfuric acid solution (1:20) and 1−2 times with cold water. Further, the dissolution of the precipitate and titration of lead is carried out in accordance with clause
The titer of 0.01 mol/dm3 solution of Trilon B (T), defined for lead, calculated by the formula
,
where m is the mass of lead in aliquotes part of standard solution, g;
V = volume of 0,01 mol/dm3 solution of Trilon B, used for titration, cm3.
3.3. Analysis
3.3.1. Decomposition with bromine
A portion of the antimony content of 1 g (in mass fraction of lead% to 2%) by weight or 0.5 g (at higher lead content) was placed in a wide-mouthed flask with a capacity of 250−300 cm3, poured 5 cm3 of hydrochloric acid (1:1) and then carefully dropwise (with continuous stirring) to 2 cm3 of bromine (reaction goes rapidly). The resulting solution was evaporated under stirring and moderate heating to dryness. The dry residue moistened with 2 cm3 of hydrochloric acid, washing its walls, poured in 0.5 cm3 of bromine, and the solution again evaporated to dryness. For the complete removal of antimony in the sludge with hydrochloric acid and bromine, repeat. Then to the dry sediment poured 5 cm3 of sulphuric acid (1:1) and again evaporated to dryness.
3.3.2. The decomposition bromatologicalacid
A portion of the antimony content of 1 g (in mass fraction of lead% to 2%) by weight or 0.5 g (at higher lead content) was placed in a wide-mouthed flask with a capacity of 250−300 cm3, poured 10 cm3 of concentrated nitric acid and evaporated to dryness. Then pour the 10 cm3 bromatological acid and the solution again evaporated to dryness. To the dry residue poured 5 cm3 bromatological acid and 3 cm3 of concentrated sulfuric acid. The contents of the flask evaporated to dryness.
3.3.3. The allocation of lead sulphate, determination of lead by
In the dry residue after decomposition, add 20 cm3 of sulphuric acid (1:6), close the flask watch glass and boil for 1 min. Then the contents of the flask cooled in running water for 1 h and filtered over a ball of filtrowanie mass. The precipitate of lead sulphate and the flask is rinsed 2−3 times with cold sulfuric acid solution (1:20), and then 1−2 times with cold water.
The precipitate together with filtrowanie ground with a glass rod was transferred to the flask, which carried out the decomposition of sample poured to 25 OM3 solution of acetate of ammonium, washing their funnel and the walls of the bulb. Then the funnel and the wall of the flask is washed with 100 cm3 of hot water and the contents of the flask heated for 5 — 10 minutes, without boiling.
After cooling, the solution was added 0.1−0.2 g of a mixture kylinalove orange with potassium nitrate and titrated the lead with a solution of Trilon B before moving purple-red color of the solution yellow.
3.4. Processing of the results
3.4.1. Mass fraction of lead (X) in percent is calculated by the formula
,
where V is the volume of 0.01 mol/dm3 solution of Trilon B, used for titration, cm3;
T is the titer of 0.01 mol/dm3 solution of Trilon B in the lead, g/cm3;
m — the weight of antimony, g.
3.4.2. The difference between the two results of parallel measurements and the difference of two analysis results with a confidence probability P=0.95 does not exceed the allowable absolute differences of precision and reproducibilityare shown in table. 2.
Table 2
───────────────────────────┬──────────────────────────────────────
Mass fraction of lead, % │allowable Absolute differences, %
├─────────────┬────────────────────────
│ convergence │ reproducibility
───────────────────────────┼─────────────┼────────────────────────
0.40 to 1.00 incl. │0,05 │0,06
SV. 1,00 «2,00» │0,10 │0,12
«2,00» 5,00 «│0,20 │0,24
(paragraph 3.4.2 as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
4. CHROMATE METHOD
The definition of lead is carried out by iodometric method after precipitation in the form of chromate. Antimony, preventing the precipitation of chromate of lead, previously removed in the form of bromide.
4.1. Apparatus, reagents and solutions
Microburette according to GOST 1770−74 with a capacity of 5 cm3.
Beakers, glass, laboratory for GOST 25336−82 with a capacity of 100 cm3.
Flasks laboratory glass according to GOST 25336−82 capacity of 500 cm3.
Cylinders measuring according to GOST 1770−74 with a capacity of 5 and 10 cm3.
Funnel glass according to GOST 23932−79.
(as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
Hydrochloric acid by the GOST 3118−77 and diluted 1:1.
Nitric acid GOST 4461−77.
Acid bromide and hydrogen GOST 2062−77.
Bromine according to GOST 4109−79.
Sodium acetate according to GOST 199−78, 15%-s'solution.
Potassium dichromate according to GOST 4220−75, 10%-NYsolution.
Sodium Chernovetskiy (thiosulfate) according to GOST 27068−86, 0.025 mol/dm3 solution.
(as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
Potassium iodide according to GOST 4232−74, 10%-NYsolution.
The starch according to GOST 10163−76, 1%-tion freshly prepared solution.
4.2. Analysis
4.2.1. Decomposition with bromine
A portion of the antimony content of 1 g was placed in a beaker with a capacity of 100 cm3, poured 5 cm3 of hydrochloric acid (1:1) and then carefully dropwise (with continuous stirring) to 2 cm3 of bromine (reaction takes place rapidly). The resulting solution was evaporated with moderate heat to dryness. For the complete removal of antimony, the residue is dissolved in 2 cm3 of hydrochloric acid, washing it the side of the Cup, pour approximately 0.5 cm3 of bromine solution and evaporate to dryness. The dry residue moistened with 10−15 drops of hydrochloric acid (1:1) and again evaporated to dryness. This operation is repeated two times.
4.2.2. The decomposition bromatologicalacid
A portion of the antimony content of 1 g was placed in a beaker with a capacity of 100 cm3, poured 5 cm3 of concentrated nitric acid, evaporating on a sand bath to dryness. To the dry residue poured 10 cm3 bromatological acid and again evaporated on a sand bath to dryness. Processing bromatological acid repeat, adding 5 cm3 bromatological acid. The dry residue moistened with 10−15 drops of hydrochloric acid (1:1) and again evaporated to dryness. This operation is repeated two times.
4.2.3. The precipitation of chromate of lead and determination of lead by
The dry residue after decomposition moistened with 8−10 drops of hydrochloric acid (1:1), slightly heated to dissolve the salts, pour the 50 cm3 of a solution of sodium acetate and heat the solution to boiling. Pour 20 cm3 of a solution of dichromate of potassium solution and the precipitate was boiled for 5−10 min and leave in a warm place for 2 hours.
At the expiration of this time the precipitate was filtered off through a filter or the ball of filtrowanie mass and washed with hot water until complete discoloration of the filter. The funnel with the precipitate is placed in a flask with a capacity of 500 cm3. The precipitate of lead chromate on the filter and remaining in the glass is dissolved in two 10 cm3 of hot hydrochloric acid (1:1), alternating with rinsing with hot water until the discoloration of the filter. The resulting solution was cooled, the volume was adjusted with water to 200 cm3, add 10 cm3 of solution of potassium iodide. The liberated iodine is titrated with a solution of sodium thiosulphate, adding the latter to light yellow color, then pour 3−4 drops of starch solution and continue the titration until the transition of the blue-violet color in green.
4.3. Processing of the results
4.3.1. Mass fraction of lead (X) in percent is calculated by the formula
,
where V is the volume of 0.025 mol/dm3 solution of sodium thiosulfate consumed for titration, cm3;
0,001725 — the amount of lead corresponding to 1 cm3 of exactly 0,025 mol/dm3 solution of sodium thiosulfate, g;
m — the weight of antimony, g.
4.3.2. The difference between the two results of parallel measurements and the difference of two analysis results with a confidence probability P=0.95 does not exceed the allowable absolute differences of precision and reproducibilityare shown in table. 2.
(paragraph 4.3.2 as amended by Change No. 1, approved. By the decree of Gosstandart of the USSR from
