GOST 6689.16-92
GOST 6689.16−92 Nickel, alloys Nickel and copper-Nickel. Methods for the determination of zinc, cadmium, lead, bismuth and tin
GOST 6689.16−92
Group B59
STATE STANDARD OF THE USSR
NICKEL, ALLOYS NICKEL AND COPPER-NICKEL
Methods for the determination of zinc, cadmium, lead, bismuth and tin
Nickel, nickel and copper-nickel alloys. Methods for the determination of zinc, cadmium, lead, bismuth and tin
AXTU 1709
Date of introduction 1993−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR
DEVELOPERS
V. N. Fedorov, Y. M. Leybov, Boris Krasnov, A. N. Bulanova, I. A. Vorobyev
2. APPROVED AND put INTO EFFECT by Decree of the Committee on standardization and Metrology of the USSR from
3. REPLACE GOST 6689.16−80
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Paragraph number section |
| GOST 8.315−91 |
2.5.3 |
| GOST 177−88 |
3.2 |
| GOST 492−73 |
Chapeau |
| GOST 860−75 |
3.2 |
| GOST 1277−75 |
2.2 |
| GOST 1467−77 |
2.2 |
| GOST 3118−77 |
3.2 |
| GOST 3640−79 |
2.2 |
| GOST 3652−69 |
3.2 |
| GOST 3760−79 |
3.2 |
| GOST 3773−72 |
3.2 |
| GOST 3778−77 |
2.2; 3.2 |
| GOST 4139−75 |
2.2 |
| GOST 4147−74 |
3.2 |
| GOST 4204−77 |
3.2 |
| GOST 4233−77 |
2.2 |
| GOST 4461−77 |
3.2 |
| GOST 4658−73 |
2.2; 3.2 |
| GOST 5828−72 |
2.2 |
| GOST 6689.1−92 |
Sec. 1; 3.2 |
| GOST 6689.12−92 |
2.2 |
| GOST 6689.15−92 |
3.2 |
| GOST 9293−74 |
2.2; 3.2 |
| GOST 10484−78 |
2.2; 3.2 |
| GOST 10928−90 |
2.2; 3.2 |
| GOST 11125−84 |
2.2 |
| GOST 14261−77 |
2.2 |
| GOST 14262−78 |
2.2 |
| GOST 19241−80 |
Chapeau |
| GOST 22180−76 |
3.2 |
| GOST 25086−87 |
Sec. 1; 2.5.3 |
| THAT 6−09−4325−76 |
3.2 |
This standard specifies the polarographic and voltammetric methods for the determination of zinc (at a mass fraction of zinc from 0.0005 to 0.6%), cadmium (at a mass fraction of cadmium from 0.0001 to 0.003%), lead (at a mass fraction of lead from 0.0002 to 0.02%), bismuth (with bismuth mass fraction of from 0.0001 to 0.005%) and tin (when the mass fraction of tin from 0.0001 to 0.003%) in Nickel, Nickel and copper-Nickel alloys according to GOST 492* and GOST 19241.
________________
* On the territory of the Russian Federation GOST 492−2006. — Note the manufacturer’s database.
1. GENERAL REQUIREMENTS
General requirements for methods of analysis GOST 25086 with the addition of sec. 1 GOST 6689.1.
2. POLAROGRAPHIC METHOD FOR THE DETERMINATION OF CADMIUM, ZINC, LEAD AND BISMUTH
2.1. The essence of the method
The method is based on preliminary separation of cadmium, zinc, lead and bismuth from the main components of the alloys by means of ion exchange chromatography and subsequent polarographic determination. When the mass fraction of impurities is less than 0.0005%, the determination is carried out by Stripping voltammetry, and for the mass concentration of more than 0.0005% using the method of oscillographic polarography or perimentally.
2.2. Apparatus, reagents and solutions
A chromatographic column made of glass, a height of 600 mm and a diameter of 15 mm (see drawing).
Polarograph AC-PPT-1 or oscilloscope FOR polarograph-5122. Allowed the use of data handling other brands.
The polarographic cell, with a capacity of 30−40 cm, made of glass with an external reference electrode (saturated calomel electrode) and mercury film electrode or a mercury dripping electrode. In the presence of polarography PPT-1 mercury film electrode can be replaced by a stationary mercury drop electrode attached to the device.
The mercury film electrode: preparation, see GOST 6689.12.
Ion-exchange resin AV-17 or an-31 at the NTD.
Wool glass.
Nitrogen gas according to GOST 9293.
Nitric acid according to GOST 11125, diluted 1:1.
Hydrochloric acid according to GOST 14261, diluted 1:1, solution 2 mol/DMand 3% solution.
Sulfuric acid according to GOST 14262 and a solution of 1 mol/DM.
Hydrofluoric acid according to GOST 10484, 40% solution.
Water bidistilled.
Potassium rodanistye according to GOST 4139, a solution of 200 g/DM.
Sodium chloride according to GOST 4233, saturated solution.
Potassium hydroxide, solution 50 and 100 g/DM.
Dimethylglyoxime according to GOST 5828, the alkaline solution of 100 g/DM.
Silver nitrate according to GOST 1277, a solution of 10 g/DM.
Mercury brand RO according to GOST 4658, does not contain moisture and purified from the oxide films (see GOST 6689.1).
Potassium chloride is the OS.CH., a solution of 1 mol/DM.
Zinc brand TSO according to GOST 3640*.
________________
* On the territory of the Russian Federation GOST 3640−94. — Note the manufacturer’s database.
Standard solutions of zinc
Solution a: 0.1 g of zinc was dissolved in a beaker with a capacity of 200 cmwhen heated in 30 cm
of hydrochloric acid (1:1), transfer the solution into a measuring flask with volume capacity of 1000 cm
and topped to the mark with water.
1 cmof the solution contains 0.0001 g of zinc.
Solution B: 10 cmsolution And evaporated almost to dryness, dissolve the residue in 20 cm
1 mol/DM
solution of potassium chloride at low heat, transfer the solution into a volumetric flask with a capacity of 100 cm
and then filled to the mark with a solution of 1 mol/DM
potassium chloride; prepared immediately before measurement,
1 cmof solution B contains 0,00001 g of zinc.
Lead brand WITH GOST 3778*.
________________
* On the territory of the Russian Federation GOST 3778−98, here and hereafter. — Note the manufacturer’s database.
Standard solutions of lead
Solution a: 0.1 g of lead dissolved in 30 cmof nitric acid (1:1), is removed by boiling the oxides of nitrogen, cooled, poured 50 cm
of water, transfer the solution into a measuring flask with volume capacity of 1000 cm
and top up with water to the mark.
1 cmof the solution contains 0.0001 g of lead.
Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm
, add 2 cm
of concentrated hydrochloric acid and topped up to the mark with water. Solution B is prepared immediately before the measurements.
1 cmof solution B has the 0.00001 g of lead.
Cadmium brand Кд0 according to GOST 1467*.
________________
* On the territory of the Russian Federation GOST 1467−93. — Note the manufacturer’s database.
Standard solutions of cadmium
Solution a: 0.1 g of cadmium was dissolved in a beaker with a capacity of 200 cmwhen heated in 30 cm
of nitric acid (1:1), is removed by boiling the oxides of nitrogen, flow 50 cm
of water, transfer the solution into a measuring flask with volume capacity of 1000 cm
and topped to the mark with water.
1 cmof the solution contains 0.0001 g of cadmium.
Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm
, add 2 cm
of hydrochloric acid and topped up to the mark with water.
1 cmof solution B contains 0,00001 g of cadmium.
Solution: 10 cmof solution B is placed in a volumetric flask with a capacity of 100 cm
, add 2 cm
of concentrated hydrochloric acid and topped up to the mark with water.
1 cmof the solution contains 0,000001 g of cadmium.
Solutions B and C were prepared immediately before measurement.
Bismuth brand Ви0 according to GOST 10928.
Standard solutions of bismuth
Solution a: 0.1 g of bismuth was dissolved in a beaker with a capacity of 100 cmwhile heating in 30 cm
of nitric acid (1:1), boil to remove oxides of nitrogen, cooled, poured 50 cm
of water, the solution is transferred into a measuring flask with volume capacity of 1000 cm
and topped to the mark with water.
1 cmof the solution contains 0.0001 g of bismuth.
Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm
, add 2 cm
of concentrated hydrochloric acid and topped up to the mark with water.
1 cmof solution B contains 0,00001 g of bismuth.
Solution: 10 cmof solution B is placed in a volumetric flask with a capacity of 100 cm
, add 2 cm
of concentrated hydrochloric acid, made up to the mark with water.
1 cmof the solution contains 0,000001 g of bismuth.
Solutions B
and prepared immediately before measurements.
2.2.1. Preparation of chromatography columns to work
50 g of the anion exchanger AV-17 or an-31 (fine fraction) was placed in a beaker with capacity of 500 cmand pour 400 cm
of a solution of potassium chloride. The resin is kept in solution for 20−24 h at room temperature. The solution is drained and the resin was washed by decantation with 3% hydrochloric acid to remove iron (no reaction with potassium romanistik). The resin was successively washed 50 g/DM
, and then 100 g/l
solutions of potassium hydroxide to remove the chloride ions (no reaction with silver nitrate). Washed the resin with distilled water until a weakly alkaline reaction wash liquid and then treat the resin with three portions of 2 mol/DM
hydrochloric acid solution to 100 cm
each.
In the lower part of the ion-exchange column is placed a pad of glass wool, filling the column with a resin height of 30−32 cm, while carefully ensure that air bubbles did not stay between the grains of resin.
After filling the column through the resin flow 50 cmof 2 mol/DM
hydrochloric acid solution.
Before analysis, a layer of hydrochloric acid over the resin must be 1−2 cm In the process and storage of the resin in the columns must remain under the fluid layer at least 2 cm
After chromatographic separation of the alloy components and their elution the resin was regenerated by flushing with water until slightly acidic reaction of pH 3 (universal indicator paper), and then a transmittance of 50 cmof 2 mol/DM
solution of hydrochloric sour
comes.
2.3. Analysis
2.3.1. The sample of alloy 2 g for the mass concentration of zinc less than 0.02% or 0.2 g when the mass fraction of zinc more than 0.02 percent is dissolved by heating in a beaker with a capacity of 200 cm, covered with watch glass, glass or plastic plate, 30 cm
of nitric acid (1:1). After removal of oxides of nitrogen by boiling the glass or plate and the side of the Cup then rinsed with water, the solution was evaporated to dryness. The dry residue is dissolved in 10 cm
of concentrated hydrochloric acid and again evaporated to dryness. Treatment of dry residue with concentrated hydrochloric acid is repeated three times, after which the dry residue is dissolved in 40 cm
of 2 mol/DM
hydrochloric acid solution and pass the solution through a column with ion-exchange resin at a speed of 3 cm
/min. bandwidth of the solution is regulated tap or clamp at the bottom of the column. After transfer the sample rinse the beaker with two portions of 20 cm
of 2 mol/DM
hydrochloric acid solution, which also passed through the column. The column was washed with 2 mol/DM
solution of hydrochloric acid to remove Nickel (alloy with an alkaline solution dimethylglyoxime) and desorbent cadmium, zinc and lead 200 cm
of water at a speed of 2 cm
/min into a glass with a capacity of 300 cm
. Then desorbent bismuth 250 cm
1 mol/DM
solution of sulphuric acid in a beaker with a capacity of 300 cm
.
The solution after desorption of zinc, cadmium and lead, is evaporated to dryness, and the solution after desorption of bismuth to a volume of 20−25 cm.
Dissolve the dry residue in 10−15 cm1 mol/DM
solution of potassium chloride at low heat, transfer the solution into a volumetric flask with a capacity of 50 cm
and made up to the marks 1 mol/DM
solution of potassium chloride.
The solution containing bismuth, transferred to a volumetric flask with a capacity of 50 cmand then filled to the mark with water. Simultaneously conduct control experience through ve
camping analysis.
2.3.2. For alloys containing tungsten
A sample of alloy weighing 2 g was dissolved with heating in a glass with a capacity of 300 cm, covered with watch glass, glass or plastic plate, 30 cm
of nitric acid (1:1). After removal of oxides of nitrogen by boiling the glass or plate and the side of the Cup then rinsed with water, the solution is evaporated to a syrupy condition and dilute with water to 70−80 cm
.
The solution is heated to 70−80 °C and filtered through a dense filter. The residue on the filter was washed with 3−4 portions for 50 cmof a hot 2% solution of nitric acid. The precipitate is discarded. The solution was evaporated to dryness, dissolve the residue in 10 cm
of concentrated hydrochloric acid and again evaporated to dryness. Then do as stated in claim
2.3.3. For alloys containing silicon, chromium and titanium
A portion of the alloy with a mass of 2 g is placed in a platinum Cup and dissolved in 20 cmof nitric acid (1:1) and 5 cm
hydrofluoric acid when heated. Cool the solution, add 5 cm
of sulphuric acid and evaporated to the appearance of smoke of sulfuric acid. Salts dissolve in water, transfer the solution into a beaker with a capacity of 300 cm
, evaporated to dryness, dissolving the dry residue in 10 cm
of concentrated hydrochloric acid and again evaporated to dryness. Then do as stated in claim
2.3.4. Determination of lead and cadmium by Stripping voltammetry method
10 cmof a solution containing zinc, lead and cadmium after Stripping, are transferred into the polarographic cell with a stationary mercury electrode and the solution degassed by nitrogen flow for 4−6 min. Set at polarography voltage minus 1.0 V, and the electrolysis is carried out while stirring the solution for 1 min (with a mass fraction of lead and cadmium in excess of 0.0003%) and 3 min (when the mass fraction of cadmium and lead is less 0,0003%). At the end of electrolysis, stop stirring, allow the grout to settle down with 15−12 and record the anodic voltammogram in the range from minus 1.0 to minus 0.2, registering peaks of electroactivity of cadmium at minus 0.6, one of the lead at minus 0,45 V.
The sensitivity of polarography is chosen so that at a given time of electrolysis, the height of the recorded peaks was not less than 10 mm.
After the registration of voltamperometry electrode kept at a potential of 0.0 V for 1 min in a stirred solution, and then repeat the measurement. When you work with standard drip electrode to each measurement get a new drop of mercury.
2.3.5. Polarographic determination of cadmium, lead and zinc for the mass concentration of zinc less than 0.02%
Aliquot part of the 25 cmof a solution containing zinc, cadmium and lead, are transferred into the polarographic cell with mercury dripping electrode and degassed by nitrogen flow for 4−6 minutes, Stop stirring and record polarogram in the range from minus 0.2 to minus 1.3, registering the waves (peaks) of the recovery of the lead at minus 0.4 V, cadmium or minus 0.65 In zinc — minus 1.0 V.
The sensitivity of polarography is chosen so that the height of the waves (peaks) of the recovery of metals was not less than 10 mm. When working with polarography-5132 measurement is carried out at a speed of 0.5−1 In the «dif.2».
2.3.6. Polarographic determination of zinc with a mass fraction of zinc more than 0,02%
Aliquot part of the solution (see table.1) obtained after desorption of zinc, is transferred into a polarographic cell. When the mass fraction of zinc more than 0,02% in a cell pre-pour 10−15 cm1 mol/DM
solution of potassium chloride.
Table 1
| Mass fraction of zinc, % |
Aliquota part of the solution, taken on polarography, cm |
| From 0.0005 to 0.02 incl. |
25 |
| SV. Of 0.02 «to 0.06 « |
15 |
| «0,06» 0,2 « |
10 |
| «0,2» 0,6 « |
3 |
Determination of lead as specified in claim 2.3.5, without registration waves (peaks) recovery of cadmium and lead.
2.3.7. Definition of bismuth by the method of Stripping voltammetry.
Aliquot part (25 cm) sulfate solution, obtained after desorption of bismuth was placed in a polarographic cell with a stationary mercury electrode, add 2 cm
of concentrated hydrochloric acid and the solution was degassed by nitrogen flow for 4−6 min. Set at polarography voltage minus 0.4 V, and the electrolysis is carried out for 1 min while stirring the solution. At the end of electrolysis, stop the stirring and allow solution to settle down for 15−20 seconds, then record the anodic voltammogram in the range from minus 0.4 to plus 0.1 V, recording the anodic peak of bismuth in the minus 0,07 V.
The sensitivity of polarography is chosen so that the peak height of bismuth was at least 10 mm.
The electrode is kept at the voltage plus 0.1 V for 1 min in a stirred solution, and then repeat the measurement. When working with a stationary drop electrode after each measurement get a new mercury drop.
2.3.8. Polarographic determination of bismuth
25 cmsulfate solution, obtained after desorption of bismuth, transferred to the polarographic cell with mercury dripping electrode, add 2 cm
of concentrated hydrochloric acid and degassed by nitrogen flow for 4−6 minutes, Stop stirring and record polarogram from 0.0 to 0.4 In minus, registering a wave (peak) recovery of bismuth at minus 0,12 V.
The sensitivity of polarography is chosen so that the wave height (peak) of bi was not less than 10 mm.
When working with polarography-5122 determination is carried out in the mode of «differential.2» at a speed of 0.25 In/sec.
2.4. Determination of cadmium, lead, zinc and bismuth by the method of additives
In the determination of cadmium and lead by Stripping voltammetry method in 0.1−0.5 cmstandard solution B In each of the metals added to the polarographic cell with the analyzed solution. The solution was stirred with a nitrogen flow of 1−2 minutes and then perform measurements as specified in claim
In the determination of bismuth by method of Stripping voltammetry of 0.1−0.5 cmstandard solution B, or bismuth is added to the polarographic cell with the analyzed solution. The solution was stirred 1−2 min with a nitrogen flow and then perform measurements as specified in claim
When polarographic determination of zinc, cadmium and lead of 0.1−0.5 cmof standard solutions And these metals are added to polarographic cell with the analyzed solution. The solution was stirred 1−2 min with a nitrogen flow and then perform measurements as specified in claim
When polarographic determination of bismuth with 0.1−0.5 cmof the standard solution And the bismuth is added to the polarographic cell with the analyzed solution. The solution was stirred 1−2 min with a nitrogen flow and then perform measurements as specified in claim
The amount of additives is chosen so that the height of the waves (peaks) of cadmium, lead, zinc and bismuth has increased 2−3 times compared to the waves (peaks) of the respective metals for the analyzed solution.
2.5. Processing of the results
2.5.1. Mass fraction of zinc, cadmium, lead and bismuth in percent is calculated by the formula
where is the wave height (peak) of zinc, cadmium, lead and bismuth for the test solution, mm;
wave height (peak) of lead, zinc, cadmium and bismuth in a control experiment, mm.
— concentration of standard solution, g/cm
;
— volume Supplement, cm
;
wave height (peak) of zinc, cadmium, lead and bismuth after the introduction of additives, mm;
— the weight of the portion of alloy, suitable aliquote part of the analyzed solution, taken on polarography,
G.
2.5.2. Discrepancies in the results of three parallel measurements (rate of convergence) and the results of the two tests
(index of reproducibility) shall not exceed the values of permissible differences given in table.2.
Table 2
| Mass fraction of zinc, cadmium, lead, bismuth and tin, % | The allowable divergence, % | |
| From 0.0001 to 0.005 incl. |
0,00008 |
0,0001 |
| SV. Of 0.005 «to 0.001 « |
0,0002 |
0,0003 |
| «To 0.001» 0,003 « |
0,0003 |
0,0004 |
| «0,003» to 0,006 « |
About 0.0006 |
0,0008 |
| «0,006» 0,010 « |
0,001 |
0,001 |
| «Is 0.01» to 0.03 « |
0,002 |
0,003 |
| «0,03» 0,06 « |
0,005 |
0,007 |
| «Of 0.06» to 0.10 « |
0,01 |
0,01 |
| «To 0.10» to 0.30 « |
0,02 |
0,03 |
| «Of 0.30» to 0.60 « |
0,05 |
0,07 |
2.5.3. Control of accuracy of analysis results is carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) of Nickel, Nickel and copper-Nickel alloys, approved under GOST 8.315*, or by a method of additives in accordance with GOST 25086.
________________
* On the territory of the Russian Federation GOST 8.315−97. — Note the manufacturer’s database.
3. POLAROGRAPHIC METHOD FOR THE DETERMINATION OF LEAD, BISMUTH AND TIN
3.1. The essence of the method
The method is based on preliminary separation of lead, bismuth and tin from the basic components of the alloy by coprecipitation with ferric hydroxide in ammonia solution and subsequent polarographic determination of lead and bismuth on the background of 1 mol/DMsolution of ammonium chloride containing 200 g/l
of citric acid or on the background of 1 mol/DM
hydrochloric acid with quinoline and lead and tin on the background of 0.5 mol/l
oxalic acid in the presence of methylene blue.
When the mass fraction of lead, tin and bismuth less than 0.0005%, their determination is carried out by Stripping voltammetry with a stationary mercury electrode. When the mass fraction of lead, tin and bismuth in excess of 0.0005% define polarographically with dripping mercuric electrode.
3.2. Apparatus, reagents and solutions
Polarograph AC-PPT-1 or oscilloscope FOR polarograph-5122.
The polarographic cell with a capacity of 30−40 cm, made of glass, with external reference electrode (saturated calomel electrode) and mercury dripping or stationary mercury electrode.
The mercury film electrode (see GOST 6689.15). In the presence of polarography PPT-1 film electrode can be replaced with a fixed drip mercury electrode attached to the device.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118 and diluted 1:1 and 5% solution.
The mixture of acids for reconstitution of concentrated nitric and hydrochloric acids in a ratio of 1:3.
Sulfuric acid according to GOST 4204.
Hydrofluoric acid according to GOST 10484, 40% solution.
Ascorbic acid according to normative-technical documentation, solution 5 g/DM.
Hydrogen peroxide according to GOST 177, a 30% solution.
Ammonia water according to GOST 3760, 1% solution.
Iron chloride according to GOST 4147, a solution of 10 g/DMin a 5% strength solution of hydrochloric acid.
Quinoline on the other 6−09−4325−76.
Ammonium chloride according to GOST 3773, solution 1 mol/DM.
Citric acid according to GOST 3652, a solution of 200 g/DM.
The background electrolyte containing 1 mol/DMammonium chloride and 200 g/l
of citric acid.
Oxalic acid according to GOST 22180, a solution of 0.5 mol/DM.
Methylene blue solution 0.001 mol/DM.
Lead brands S0 GOST 3778.
Standard solutions of lead (see p.2.2).
Bismuth brand Ви100 according to GOST 10928.
Standard solutions of bismuth (see p.2.2).
Tin stamps 00 GOST 860.
Standard solutions of tin
Solution a: 0.1 g of tin are placed in a beaker with a capacity of 100 cm, add 0.75 g of sodium chloride, 15 cm
of concentrated hydrochloric acid, cover with watch glass, glass or plastic plate and dropwise added hydrogen peroxide until complete dissolution of the metal when heated. To the obtained solution poured 20−30 cm
of water, transfer the solution into a measuring flask with volume capacity of 1000 cm
, add 50 cm
of concentrated hydrochloric acid and add water to the mark.
1 cmof the solution contains 0.0001 g of tin.
Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm
, add 5 cm
of concentrated hydrochloric acid and topped up to the mark with water.
1 cmof solution B contains 0,00001 g tin.
Solution: 10 cmof a solution transferred to a volumetric flask with a capacity of 100 cm
, add 5 cm
of concentrated hydrochloric acid, made up to the mark with water.
1 cmof the solution contains 0,000001 g tin.
Solutions B and C were prepared immediately before measurement.
Nitrogen gas according to GOST 9293.
Mercury brands r0 according to GOST 4658, does not contain moisture and purified from the oxide film (
see GOST 6689.1).
3.3. Analysis
3.3.1. For alloys not containing chromium, titanium and silicon
A sample of alloy weighing 1 g is placed in a beaker with a capacity of 200−250 cm, add 15−20 cm
of the mixture of acids to dissolve, cover with a watch glass, a glass or plastic plate and dissolved by heating. After dissolution, the sample is rinsed glass or plate and walls of glass with water and dilute the solution with water up to 130−150 cm
.
To the obtained solution poured 1 cmof ferric chloride and add solution of ammonia until the formation of soluble ammonia complexes of Nickel and copper and 5 cm
of excess ammonia.
The solution is kept at 60−70 °C for 20 min and filtered through a filter of medium density. The glass and the filter cake was washed with 3−4 portions at 25−30 cmof hot 1% solution of ammonia. Funnel with a filter placed over a glass, which was carried out the precipitation, wash the precipitate with filter glass 30 cm
of hot water, the filter washed with 20 cm
of hydrochloric acid (1:1) and the solution was heated until complete dissolution of the precipitate. Diluted solution into the beaker with water up to 130−150 cm
and repeat the deposition of two RA
for.
3.3.2. In the determination of lead and bismuth after three perioadele the precipitate from the filter washed into the beaker 20 cmof hot water, the filter washed with 5 cm
of hydrochloric acid (1:1), dissolve the precipitate in a beaker 15 cm
of hydrochloric acid (1:1) and evaporated the solution to dryness.
3.3.2.1. The dry residue is dissolved in 20 cmof the background electrolyte under low heat, transfer the solution into a volumetric flask with a capacity of 50 cm
and add to the labels of background electrolyte. Simultaneously conduct control experience through the entire course of the analysis.
3.3.2.2. The dry residue is dissolved in 10 cmof hydrochloric acid (1:1), the solution transferred to a volumetric flask with a capacity of 50 cm
, add 1.5 cm
of a solution of ascorbic acid, 0.5 cm
quinoline and topped to the mark with water. Simultaneously conduct control experience through the entire course of the analysis.
3.3.3. In the determination of lead and tin after three perioadele the precipitate from the filter washed into the beaker 20 cmof hot water, washed the filter 15 cm
hot 0.5 mol/DM
solution of oxalic acid and dissolve the precipitate when heated. Transfer the solution into a measuring flask with a capacity of 50 cm
and then filled to the mark 0.5 mol/DM
solution of oxalic acid. Simultaneously conduct control experience through the entire course of the analysis.
3.3.4. For alloys containing chrome and silicon
A sample of alloy weighing 1 g is placed in a platinum Cup, add 20 cmof nitric acid (1:1), 5 cm
hydrofluoric acid and dissolved by heating. Then the solution was cooled, add 5 cm
of sulphuric acid and the solution is evaporated until a white smoke of sulfuric acid. Dissolve the resulting salt in water, transfer the solution into a glass with a capacity of 250 cm
, dilute with water to 130−150 cm
and further analysis is carried out, as indicated in the claims.3.1; 3.3.2
3.4. Determination of lead and bismuth by method of Stripping voltammetry
Placed in a polarographic cell with a stationary mercury electrode is 10−15 cm, background electrolyte, add aliquot part (10 cm
) of the analyzed solution and degassed the solution in the cell with a nitrogen flow for 4−6 min.
Set on polarography voltage minus 0.8 V and carry out the electrolysis of lead and bismuth while stirring the solution. When the mass fraction of lead and bismuth in the alloy is less than 0,0003%, the electrolysis is carried out 3−4 min, and at higher contents of 1 min At the end of electrolysis, stop stirring, allow the solution to settle down for 15−20 seconds, then record the anodic voltammogram at linearly varying the electrode potential from -0.8 to 0.0 V, recording the peak of the lead at minus 0.55 V and peak of bismuth at minus 0.15 V.
The sensitivity of the instrument when registering voltamperometry is chosen so that the height of the recorded peaks of lead and bismuth was not less than 10 mm.
Preparation of electrodes to the next measurement is carried out as specified in clause
3.5. Determination of lead and tin by Stripping voltammetry method
Placed in a polarographic cell of 15 cmmol/DM
solution of oxalic acid, add aliquot part (5 cm
) test solution, add 1−2 drops of 0.001 mol/DM
solution of methylene blue and degassed the solution in the cell for 4−6 min nitrogen flow. Set on polarography voltage minus 0.8 V and carried out the concentration of lead and tin for 1−3 min on the stationary mercury electrode in a continuously stirred solution. At the end of electrolysis, stop stirring, allow the grout to rest for 15−20 s, after which the recorded anodic polarization curve with linearly varying electrode potential from minus 0.8 to minus 0.2 In, locking electrofactory the peaks of tin at minus 0.65 of the lead at minus 0.5 V.
The sensitivity of the device is chosen so that the height of the recorded peaks was not less than 10 mm.
Preparation of electrodes to the next measurement is carried out as specified in clause
The contents of lead and tin find by the method of additions as described in section 2.4, using the standard solutions Used In lead and tin.
3.6. Polarographic determination of lead and bismuth
Aliquot part of the solution (25 cm) in PP.3.3.2.1 and
The content of lead and bismuth find by the method of additions as described in section 2.4, using standard solutions And lead and bismuth.
3.7. Polarographic determination of lead and tin
Aliquot part of the oxalate solution (25 cm) are transferred into the polarographic cell with mercury dripping electrode, add 1−2 drops of 0.001 mol/DM
solution of methylene blue and degassed the solution for 4−6 min nitrogen flow. Stop stirring and remove the cathode polarogram, registering the waves (peaks) of the recovery of the lead at minus 0.5 V and tin — at minus 0,65 V.
The sensitivity of polarography is chosen so that the height of the recorded peaks was not less than 10 mm.
The contents of lead and tin find by the method of additions as described in section 2.4, using standard solutions And lead and tin.
3.8. Processing of the results
3.8.1. Mass fraction of lead, bismuth and tin in percent is calculated by the formula
where is the wave height (peak) of lead, bismuth or tin in polarography the test solution, mm;
wave height (peak) of lead, bismuth and tin in a control experiment, mm.
— concentration of standard solution, g/cm
;
— volume Supplement, cm
;
— the height of the waves (peaks) of lead, bismuth, or tin after the introduction into the cell of additives, mm;
— the weight of the portion of alloy, suitable aliquote part of the solution, taken on polarography,
G.
3.8.2. Discrepancies in the results of three parallel measurements (rate of convergence) and the results of the two tests
(index of reproducibility) shall not exceed the values of permissible differences given in table.2.
3.8.3. Control of accuracy of analysis results is carried out as specified in clause
