GOST 24978-91
GOST 24978−91 (ISO 4740−85) Alloys copper-zinc. Methods for determination of zinc
GOST 24978−91
(ISO 4740−85)
Group B59
STATE STANDARD OF THE USSR
ALLOYS COPPER-ZINC
Methods for determination of zinc
Copper-zinc alloys. Methods for determination of zinc
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, L. V. Morea, A. I. Vorobyov
2. APPROVED AND promulgated by the Decree of Committee of standardization and Metrology of the USSR from
3. The application of this standard prepared by the direct application of international standard ISO 4740−85 «Copper and copper alloys. The determination of zinc. Flame atomic absorption spectrometric method"
4. REPLACE GOST 24978−81
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document, to which this links |
The number of the paragraph, section, applications |
| GOST 8.315−91 |
2.5.4, 5.5.4 |
| GOST 61−75 |
5.2 |
| GOST 83−79 |
5.2 |
| GOST 199−78 |
5.2 |
| GOST 1652.1−77 |
5.2 |
| GOST 3117−78 |
5.2 |
| GOST 3118−77 |
2.2, 3.2, 4.2, 5.2 |
| GOST 3640−79 |
2.2, 3.2, 4.2, 5.2 |
| GOST 3760−79 |
2.2, 4.2, 5.2 |
| GOST 3773−72 |
4.2, 5.2 |
| GOST 4204−77 |
4.2, 5.2 |
| GOST 4220−75 |
2.2 |
| GOST 4233−77 |
2.2, 4.2 |
| GOST 4461−77 |
2.2, 3.2, 4.2, 5.2, app |
| GOST 4463−76 |
5.2 |
| GOST 4518−75 |
2.2 |
| GOST 5817−77 |
5.2 |
| GOST 5828−77 |
4.2, 5.2 |
| GOST 6344−73 |
2.2 |
| GOST 10484−78 |
App |
| GOST 20448−90 |
2.2 |
| GOST 24231−80 |
App |
| GOST 25086−87 |
Sec. 1, 4.4, 5.4.4 |
This standard establishes titrimetric chelatometric methods for the determination of zinc with a mass fraction of zinc from 3 to 45% and the atomic absorption method for the determination of zinc with a mass fraction of zinc from 3 to 10% in copper-zinc alloys according to GOST 15527 and GOST 17711.
Allowed to carry out the determination of zinc in copper-zinc alloys according to international standard ISO 4740−85 given in the Appendix.
1. GENERAL REQUIREMENTS
General requirements for methods of analysis GOST 25086 with the addition of: analysis result should be the arithmetic mean of three (two) of parallel definitions.
2. TITRIMETRIC COMPLEX-METRIC METHOD
2.1. The essence of the method
The method is based on dissolving the alloy in a mixture of hydrochloric and nitric acids, masking interfering elements with thiourea, ammonium citrate and ammonium thiocyanate, extraction of the complex of zinc with methyl isobutyl ketone, Stripping to the aqueous phase and titration of the zinc at a pH of 5.0 to 5.2 with a solution of Trilon B in the presence kylinalove orange.
2.2. Reagents and solutions
Hydrochloric acid according to GOST 3118, diluted 1:1 and 1:4.
Nitric acid according to GOST 4461, diluted 1:1.
A mixture of hydrochloric acid (1:1) and nitric acid in the ratio 3:1.
Ammonia water according to GOST 3760.
Thiourea according to GOST 6344 and solution mass concentration of 50 g/DM.
Treasuremania ammonium citrate or ammonium citrate dvosemyanny.
Ammonium radamisty according to GOST 19522.
A mixture of masking reagent: 60 g of thiourea, 100 g of ammonium citrate and 150 g Rodenstock ammonium dissolved in 1 DMof water.
Methyl isobutyl ketone (MIBK).
Wash solution: 250 cmsolution the masking reagents are mixed in a 250 cm
water and 25 cm
of a hydrochloric acid solution, diluted 1:4.
Ammonium fluoride according to GOST 4518, solution 5 g/DM.
Sodium chloride according to GOST 4233.
Selenology orange, a mixture of sodium chloride in the ratio of 1:100.
Hexamethylenetetramine (hexamine).
Zinc metal stamps C0 according to GOST 3640*.
________________
* On the territory of the Russian Federation GOST 3640−94. Here and further. — Note the manufacturer’s database.
Standard zinc solution: 1.0 g of zinc is dissolved in 10 cmof hydrochloric acid (1:1), transferred into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.001 g of zinc.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652, 0.05 mol/DMsolution: 18,61 g Trilon B dissolved in water by heating, the solution is transferred into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and peremeci
vayut.
2.3. Determination of the mass concentration of the solution Trilon B for zinc
50 cmstandard solution of zinc is placed in a separating funnel with a capacity of 250 cm
, are added dropwise ammonia until the appearance of unfading light haze. Then add 50 cm
of hydrochloric acid (1:4), 50 cm
of masking solution mixture and further act in accordance with paragraph 2.4.
The mass concentration of the solution Trilon B (), expressed in grams of zinc on 1 cm
of a solution, calculated by the formula
0,05 where is the mass of zinc, taken for titration, g; — volume of solution Trilon B, spent on titration, sm
.
2.4. Analysis
Depending on the mass fraction of the zinc portion of the alloy (tab.1) is placed in a beaker with a capacity of 250 cmand dissolved by heating in 25 cm
of a solution of the mixture of acids. After complete dissolution of the sample solution was boiled to remove oxides of nitrogen. The solution was then cooled, transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Table 1
| Mass fraction of zinc, % |
The mass of charge, g |
The volume aliquote part of the solution, cm | ||||
| From | 3,0 | to | 10,0 | incl. | 1 |
50 |
| SV. | 10,0 | « | 20,0 | « | 2 |
25 |
| « | 20,0 | « | 30,0 | « | 0,5 |
25 |
| « | 30,0 | « | 45,0 | « | 0,5 |
20 |
Aliquot part of the solution (table.1) is placed in a separating funnel with a capacity of 250 cm, top up with water to 50 cm
and with stirring add dropwise ammonia until the appearance of unfading light haze. Then add 5 cm
of hydrochloric acid (1:1) and with careful stirring, 70 cm
(with a mass fraction of zinc from 3 to 10%) or 50 cm
(with a mass fraction of zinc more than 10%) solution of a masking compound. Then add 50 cm
of methyl isobutyl ketone and shake vigorously for 2 min. After phase separation, the aqueous phase is transferred to a second separatory funnel with a capacity of 250 cm
, add 20 cm
of methyl isobutyl ketone and the extraction repeated. After separation of the layers the aqueous phase is decanted and discarded and the organic phase is attached to the content in the first separating funnel. The second separating funnel rinse the combined extracts in the first separating funnel.
After separation of the phases and remove the aqueous phase, and washed organic phase was placed in a beaker with a capacity of 400 cm. Separating funnel rinse the 25 cm
hydrochloric acid (1:4), then with 100 cm
of water and both of wash solution are attached to the organic phase. Add 20 cm
of a solution of ammonium fluoride, 20 cm
of a solution of thiourea and the solution is thoroughly mixed.
Add a pinch of spatula of 0.1 g of a mixture xrenovo orange with sodium chloride and injected in small portions methenamine until you see a red-purple color of the aqueous phase and establishing a pH of 0.5 to 5.2 on indicator paper «Rfat» zinc and titrated with a solution of Trilon B with stirring of both phases to the transition of red-violet color of the aqueous phase in yellow. Before the end of the titration control the pH of the solution and, if necessary, add hexamine or hydrochloric acid (1:4) to establish a pH of 5.0 to 5.2 and titrated by adding a solution of Trilon B dropwise while thoroughly mixing the two
of their phases.
2.5. Processing of the results
2.5.1. Mass fraction of zinc () in percent is calculated by the formula
where — volume of solution Trilon B, used for titration, cm
;
— mass concentration of the solution Trilon B, expressed in grams of zinc, 1 cm
;
— the weight of the portion corresponding to aliquote part of the sample solution,
2.5.2. Discrepancies in the results of three parallel definitions should not exceed the values permitted by the divergence (
the rate of convergence) given in table.2.
Table 2
| Mass fraction of zinc, % |
|
| ||||
| From |
3 |
to |
5 |
incl. | 0,10 |
0,14 |
| SV. |
5 |
« |
15 |
« |
0,15 |
0,21 |
| « |
15 |
« |
30 |
« |
0,25 |
0,35 |
| « |
30 |
« |
45 |
« |
0,30 |
0,42 |
2.5.3. Discrepancies in the results analysis, obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (
a measure of reproducibility) shall not exceed the values given in table.2.
2.5.4. Control of accuracy of analysis results is carried out according to State standard samples copper zinc alloy approved by GOST 8.315*, or a comparison of the results obtained by atomic absorption method, in accordance with GOST 25086.
________________
* On the territory of the Russian Federation GOST 8.315−97. Here and further. — Note the manufacturer’s database.
3. ATOMIC ABSORPTION METHOD
3.1. The essence of the method
The method is based on dissolving the sample alloy in a mixture of hydrochloric and nitric acids and measuring the atomic absorption of zinc in the flame of acetylene-air at a wavelength of 213,8 nm.
3.2. Apparatus, reagents and solutions
Atomic absorption spectrometer with a radiation source for zinc.
Hydrochloric acid according to GOST 3118, diluted 1:1.
Nitric acid according to GOST 4461, diluted 1:1.
A mixture of hydrochloric and nitric acids in the ratio 1:1.
Zinc metal stamps C0 according to GOST 3640.
Standard solutions of zinc
Solution a: 0.1 g of zinc is dissolved in 30 cmof hydrochloric acid, transferred into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof solution A contains 0.1 mg of zinc.
Solution B: 25 cmsolution And placed in a volumetric flask with a capacity of 250 cm
, made up to the mark with water and mix.
1 cmof a solution contains 0.01 mg of zinc.
3.3. Analysis
3.3.1. A sample of alloy weighing 0.2 g were placed in a glass with a capacity of 250 cm, and dissolved in 30 cm
of a mixture of acids.
The solution was cooled, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.
In a volumetric flask with a capacity of 100 cmis placed aliquot part of the solution to 5 cm
, add 2 cm
of hydrochloric acid, made up to the mark with water and mix.
Measure the atomic absorption of zinc in the sample solution in parallel with the solution to construct the calibration curve and the solution in the reference experiment in the flame acetylene-air using radiation at a wavelength of 213,8 nm.
3.4. Construction of calibration curve
In seven of the eight volumetric flasks with a capacity of 100 cmis placed 2,0; 4,0; 6,0 and 8,0 cm
standard solution B zinc; 1,0; 1,5 and 2,0 cm
standard solution And zinc, which corresponds to 0,02; 0.04; 0,06; 0,08; 0,10; 0,15 and 0.20 mg of zinc.
All flasks is poured on 2 cmof hydrochloric acid, made up to the mark with water and mix. Measure the atomic absorption of zinc immediately before and after measuring the absorption of zinc in the analyzed solution.
3.5. Processing of the results
3.5.1. Mass fraction of zinc () in percent is calculated by the formula
where is the concentration of zinc in the sample solution, found by calibration schedule, g/cm
;
the concentration of zinc in solution in the reference experiment, was found in the calibration schedule, g/cm
;
— volume of the volumetric flask for preparation of the final solution of the sample, cm
;
— the weight of the portion corresponding to aliquote part of the solution, g
.
3.5.2. Discrepancies in the results of parallel definitions should not exceed the values permitted by the divergence (
the rate of convergence) given in table.2.
3.5.3. Discrepancies in the results analysis, obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (
a measure of reproducibility) shall not exceed the values given in table.2.
3.5.4. Control of accuracy of analysis results is carried out according to State standard samples copper zinc alloy approved by GOST 8.315, or by additives or by comparing the results obtained with titrimetric method, in accordance with GOST 25086.
4. TITRIMETRIC CHELATOMETRIC METHOD
4.1. The essence of the method
The method is based on complexometric titration of zinc in the presence of Chromogen black as indicator after the separation of copper with sodium thiosulphate and the binding of iron and Nickel in the complex of ammonium with a solution dimethylglyoxime.
4.2. Reagents and solutions
Nitric acid according to GOST 4461, diluted 1:1.
Hydrochloric acid according to GOST 3118, diluted 1:1.
The mixture of acids to dissolve fresh: one volume of nitric acid mixed with three volumes of hydrochloric acid.
Sulfuric acid according to GOST 4204.
Ammonia water according to GOST 3760.
Ammonium chloride according to GOST 3773, a solution of 250 g/DM.
Chernovetskiy sodium (thiosulfate), a solution of 200 g/DM.
Sodium chloride according to GOST 4233.
Potassium dichromate according to GOST 4220, a solution of 100 g/DM. Dimethylglyoxime according to GOST 5828, a solution of 10 g/DM
of ammonia.
Methyl red, solution 1 g/DM.
The Chromogen black.
Indicator mixture: Chromogen black well triturated with the sodium chloride in the ratio of 1:100.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652, solutions of 0.025 and 0.01 mol/DM, prepare fiksanala or as follows: 9,305 g or 3,7224 g Trilon B dissolved in 500 cm
of water when heated, transferred to a volumetric flask with a capacity of 1 DM
and topped to the mark with water.
Zinc GOST 3640, brand or C0 Ц00.
Standard zinc solution: 0.1 g of zinc metal are dissolved in 15 cmof hydrochloric acid (1:1) solution was evaporated to dryness, the dry residue dissolved in 10 cm
of hydrochloric acid (1:1) and transferred to a volumetric flask with a capacity of 100 cm
and then filled to the mark with water.
1 cmof the solution contains 0.001 g of zinc.
Determination of the mass concentration of the solution Trilon B.
25 cmstandard solution of zinc is placed in a conical flask with a capacity of 500 cm
, adding 25 cm
of a solution of ammonium chloride, 2−3 drops methyl red and the solution is neutralized with ammonia solution dimethylglyoxime to the transition of color from red to yellow and even an excess of 5 cm
, then add 5−6 drops of a solution of potassium dichromate, the indicator mixture and the solution was titrated with Trilon B before the transition red-violet color in green.
The mass concentration of the solution Trilon B (), expressed in grams of zinc on 1 cm
of a solution, calculated by the formula
where is the mass of zinc, taken for titration, g;
— volume of solution Trilon B, spent on titration, sm
.
4.3. Analysis
A sample of alloy weighing 0.2 g were placed in a glass with a capacity of 250 cm, adding 10 cm
of the mixture of acids and dissolved by heating. The cooled solution was added 4 cm
of sulphuric acid and evaporate to release white smoke of sulfuric acid. The residue is cooled, rinse the walls of the glass with water and again evaporated to release white smoke of sulfuric acid. To the cooled residue add 80 cm
of water and heated to dissolve the salts. The cooled solution is transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix. In alloys containing lead, the flask is allowed to stand for settling of the precipitate of lead sulfate. You can filter the precipitate through dense dry filter into a dry flask. Then select aliquot part of the solution (see table.3), placed in a beaker with a capacity of 250 cm
and add water up to 100 cm
. The solution was added sodium thiosulfate until the appearance of white turbidity, boil the solution to coagulate the precipitate of copper sulfide and produce a clear solution above the sediment. The solution was filtered through the filter into the conical flask with a capacity of 500 cm
, the filter cake washed several times with hot water and discarded.
Table 3
| Mass fraction of zinc, % |
Aliquota part of the solution, see |
A charge corresponding to aliquote part of the solution, g |
The concentration of Trilon B solution, mol/DM | ||||
| From | 3 | to | 10 | incl. | 50 |
0,1 |
0,01 |
| SV. | 10 | « | 20 | « | 25 |
0,05 |
0,025 |
| « | 20 | « | 30 | « | 15 |
0,03 |
0,025 |
| « | 30 | « | 45 | « | 10 |
0,02 |
0,025 |
To the filtrate add 25 cmof a solution of ammonium chloride to keep the zinc in solution, 2−3 drops of methyl red and the solution is neutralized with ammonia solution dimethylglyoxime to the transition of color from red to yellow and even an excess of 5 cm
. To the solution add 5−6 drops of a solution of potassium dichromate, the indicator and the mixture titrated with Trilon B (see table.3), the transition red-violet color in green.
4.4. Processing of the results
4.4.1. Mass fraction of zinc () in percent is calculated by the formula
where — volume of solution Trilon B, used for titration, cm
;
— mass concentration of the solution Trilon B for zinc, g/cm
;
— the weight of the portion corresponding to aliquote part of the sample solution,
4.4.2. Discrepancies in the results of three parallel definitions should not exceed the values permitted by the divergence (
the rate of convergence) given in table.2.
4.4.3. Discrepancies in the results analysis, obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (
a measure of reproducibility) shall not exceed the values given in table.2.
4.4.4. Control of accuracy of analysis results is carried out according to State standard samples copper zinc alloy approved by GOST 8.315, or a comparison of the results obtained by atomic absorption method, in accordance with GOST 25086.
5. TITRIMETRIC CHELATOMETRIC METHOD
5.1. The essence of the method
The method is based on complexometric titration of zinc in the presence kylinalove orange as indicator after prior separation of copper and lead by electrolysis, manganese — as manganese dioxide, iron — hydroxide, Nickel — in the form of dimethylglyoximate, precipitated from the electrolyte at the same time.
5.2. Apparatus, reagents and solutions
Installation of electrolysis with a platinum mesh electrode according to GOST 6563.
Nitric acid according to GOST 4461, diluted 1:1.
Hydrochloric acid according to GOST 3118, diluted 1:1.
Sulfuric acid according to GOST 4204, diluted 1:4.
Tartaric acid according to GOST 5814, a solution of 500 g/DM.
Acetic acid according to GOST 62, 0.1 mol/DMsolution.
Ammonia water according to GOST 3766, diluted 1:1.
Ammonium chloride according to GOST 3773, solution 20 g/DM.
Ammonium neccersarily according to GOST 20478, a solution of 200 g/DM.
Sodium fluoride according to GOST 4463, a solution of 200 g/DM.
Dimethylglyoxime according to GOST 5828, a solution of 5 g/DM.
Selenology orange, aqueous solution 0,5 g/DM.
Sodium carbonate according to GOST 83, a saturated solution.
Ammonium acetate according to GOST 3117.
Sodium acetate according to GOST 199.
Buffer solution pH=5.5 to 5.7:18 g sodium acetate, 46 g of ammonium acetate and 20 cmof acetic acid are dissolved in 1 DM
of water. Check and set the pH of the solution on the pH meter by adding acetic acid or ammonia.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652, solution 0,05 mol/DM(see preparation p.2.2).
Zinc GOST 3640, brand or C0 Ц00.
Standard solution of zinc (see preparation p.2.2).
Determination of the mass concentration of the solution Trilon B.
5 cmstandard solution of zinc is placed in a conical flask with a capacity of 500 cm
, add 1 cm
of a solution of tartaric acid, 5 cm
of a solution of sodium fluoride and the solution neutralized with ammonia to pH=5 by the paper «the Congo». Then add 40 cm
buffer solution, 1 cm
kylinalove orange solution and the solution was titrated with Trilon B before moving the lilac colouring in yellow.
The mass concentration of the solution Trilon B (), expressed in grams of zinc on 1 cm
of a solution, calculated by the formula
where is the mass of zinc, taken for titration, g;
— volume of solution Trilon B, spent on titration, sm
.
5.3. Analysis
A sample weighing 1 g is placed in a beaker with a capacity of 250 cm, add 15 cm
of a solution of nitric acid, cover with watch glass and dissolve first without heating and then with heating.
After dissolution of the sample and removal of nitrogen oxides by boiling the rinsed glass and walls of beaker with water, diluted the solution with water to 100−150 cm(if the alloy contains tin, it is filtered off), add 7 cm
of a solution of sulphuric acid and produce copper by electrolysis according to GOST 1652.1. If the alloy contains lead in excess of 0.5%, the sulfuric acid solution is added in 25 to 30 minutes after the start of electrolysis.
The electrolyte, after separation of copper, is transferred into a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.
Select aliquot part of the solution — 50 cmin a beaker with a capacity of 250 cm
, add water 50 cm
and if the alloy contains manganese, more than 0.5%, then neutralized with ammonia and sodium carbonate to pH=3−4 by universal indicator paper. The solution is heated nearly to boiling, add 10 cm
naternicola solution of ammonium to precipitate the manganese in the manganese dioxide, the solution is boiled under a lid until the destruction naternicola ammonium and then cool the solution.
The solution was neutralized to pH=5−6 with aqueous ammonia and give back in excess of 3 cm. The solution was then heated to 60 °C, add 20 cm
of solution dimethylglyoxime for the deposition of Nickel and the solution and the precipitate is kept for 20−30 minutes in a dark place. The precipitate was filtered off on a medium density filter, washed with a solution of ammonium chloride 8−10 times, collecting the filtrate in a beaker, which was carried out the deposition of Nickel.
The filtrate is transferred to a volumetric flask with a capacity of 100 cmup to the mark, top up with water and mix.
In a conical flask with a capacity of 250 cmis placed aliquot part of the solution (see table.3) add 1 cm
of a solution of tartaric acid, 5 cm
of a solution of sodium fluoride and the solution is neutralized with ammonia solution on the paper «the Congo» until pH=5. Then add 40 cm
buffer solution, 1 cm
kylinalove orange and the solution was titrated with Trilon B to switch the color of the solution from purple
in yellow.
5.4. Processing of the results
5.4.1. Mass fraction of zinc () in percent is calculated by the formula
where — volume of solution Trilon B, used for titration, cm
;
— mass concentration of the solution Trilon B for zinc, g/DM
;
— the weight of the portion corresponding to aliquote part of the sample solution,
5.4.2. Discrepancies in the results of three parallel definitions should not exceed the values permitted by the divergence (
the rate of convergence) given in table.2.
5.4.3. Discrepancies in the results analysis, obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (
a measure of reproducibility) shall not exceed the values given in table.2.
5.4.4. Control of accuracy of analysis results is carried out according to State standard samples copper zinc alloy approved by GOST 8.315, or a comparison of the results obtained by atomic absorption method, in accordance with GOST 25086.
APPLICATION (recommended). ISO 4740. COPPER AND COPPER ALLOYS. THE DETERMINATION OF ZINC. Flame atomic absorption spectrometric method
APP
Recommended
ISO 4740−85 COPPER AND COPPER ALLOYS
DETERMINATION OF ZINC
Flame atomic absorption spectrometric method
1. Scope
This international standard specifies the flame atomic absorption spectrometric method for the determination of the mass fraction of zinc in copper and copper alloys of all types, except for alloys containing more than 10% lead.
The method is applicable when the mass fraction of zinc from 0.001 to 6%.
2. Link
ISO 1811. (GOST 24231). Copper and copper alloys. Selection and preparation of samples for chemical analysis.
Part 1. Sampling from cast products.
Part 2. Sampling from semi-finished products obtained by pressure treatment, and casting.
3. The essence of the method
The method is based on dissolving the sample in a mixture of hydrofluoric, boric and nitric acids, and spraying the solution in a flame air-acetylene torch spectrometer. The measurement of the absorption of the resonance lines of zinc (atomic absorption) is produced at a wavelength of 213,8 nm.
Measure the atomic absorption of zinc in the sample solution in parallel to the calibration solutions.
4. Reagents
The analysis used reagents qualifications h. d. a. and distilled or deionized water.
4.1. A mixture of hydrofluoric, boric and nitric acids
Mix 300 cmof boric acid solution (concentration of 40 g/DM
), 30 cm
hydrofluoric acid (GOST 10484), 500 cm
of nitric acid (GOST 4461) and 150 cm
of water.
4.2. Copper, background solution
Weigh 10 g of copper containing not more than 0,0002% of zinc, in a Teflon beaker with a capacity of 1000 cm. Add 400 cm
of the mixture of acids and heated until complete dissolution of copper. Boil the solution until the termination of allocation of steams of nitric oxide brown. Cool and pour the solution into volumetric flask with a capacity of 500 cm
. Topped up to the mark with water and mix.
50 cmof this solution contain 1 g of copper and 40 cm
of a mixture of acids.
4.3. Zinc, the primary standard solution containing 5 g/DMof zinc
Put (2,5±0,0001) g of zinc metal (purity 99.99%) in a tall glass with a capacity of 250 cm. Add 50 cm
of nitric acid (GOST 4461−77 diluted 1:1), covered with a glass cover and gently heated until dissolution of the metal. Boil the solution for several minutes to stop the allocation of steams of nitric oxide, then cooled. Pour the solution into volumetric flask with a capacity of 500 cm
, made up to the mark with water and mix.
1 cmof this standard solution contains 5 mg of zinc.
4.4. Zinc, standard solution containing 0.5 g/lof zinc
Put 100,0 cmprimary standard solution zinc volumetric flask with a capacity of 1000 cm
. Topped up to the mark with water and mix.
1 cmof this standard solution contains 0.5 mg of zinc.
4.5. Zinc, standard solution containing 0.05 g/lof zinc
Placed 10.0 cmprimary standard solution zinc volumetric flask with a capacity of 1000 cm
. Topped up to the mark with water and mix.
1 cmof this standard solution contains 0.05 mg of zinc.
4.6. Zinc, standard solution containing 0.01 g/lof zinc
Place 2.0 cmof the primary standard solution zinc volumetric flask with a capacity of 1000 cm
. Topped up to the mark with water and mix.
1 cmof this standard solution contains 0.01 mg of zinc.
5. Equipment
Common laboratory apparatus with the addition of:
5.1. The Teflon beakers with a capacity of 1000 and 250 cm.
5.2. Burette with divisions of 0.05 cm.
5.3. Flame atomic absorption spectrometer. A lamp with a zinc hollow-cathode or electrodeless discharge lamp.
5.4. Compressor for supplying compressed air.
5.5. The cylinder with acetylene.
6. Sampling
Sampling is made in accordance with the international standard ISO 1811. The metal should preferably be in the form of drilling shavings of a thickness not exceeding 0,3 mm.
7. Analysis
7.1. Preparation of the calibration solutions
7.1.1. Mass fraction of zinc from 0.001 to 0.01%
Four volumetric flasks with a capacity of 100 cmis placed a standard solution of zinc concentration of 0.01 g/DM
and a background solution of copper in the amount indicated in the table.1. Topped up to the mark with water and mix.
Table 1
The volume of a standard solution of zinc (for n.4.6), cm |
The volume of the background solution of copper (according to claim 4.2) cm |
The mass of zinc in 100 cm |
| 0* |
50 |
0 |
| 1 |
50 |
0,01 |
| 5 |
50 |
0,05 |
| 10 |
50 |
0,10 |
________________
* Blank sample for calibration.
7.1.2. Mass fraction of zinc from 0.005 to 0.06%
In six volumetric flasks with a capacity of 200 cmis placed a standard solution of zinc concentration of 0.05 g/DM
and a background solution of copper in the amount indicated in the table.2. Topped up to the mark with water and mix.
Table 2
The volume of a standard solution of zinc (for n.4.5) cm |
The volume of the background solution of copper (according to claim 4.2) cm |
The mass of zinc in 100 cm |
| 0* |
50 |
0 |
| 1 |
50 |
0,025 |
| 2 |
50 |
0,050 |
| 4 |
50 |
0,10 |
| 8 |
50 |
0,20 |
| 12 |
50 |
0,30 |
________________
* Blank sample for calibration.
7.1.3. Mass fraction of zinc from 0.05 to 0.60%
In six volumetric flasks with a capacity of 200 cmis placed a standard solution of zinc concentration of 0.5 g/DM
and a background solution of copper in the amount indicated in the table.3. Topped up to the mark with water and mix. 100 cm
of the resulting solutions was placed in six volumetric flasks with a capacity of 1000 cm
, top up each flask to the mark with water and mix.
Table 3
The volume of a standard solution of zinc, cm |
The volume of the background solution of copper, see |
The mass of zinc in 100 cm |
| 0* |
50 |
0 |
| 1 |
50 |
0,025 |
| 2 |
50 |
0,05 |
| 4 |
50 |
0,10 |
| 8 |
50 |
0,20 |
| 12 |
50 |
0,30 |
________________
* Blank sample for calibration.
7.1.4. Mass fraction of zinc of 0.5 to 6%
In six volumetric flasks with a capacity of 200 cmis placed a standard solution of zinc with a concentration of 5 g/DM
and a background solution of copper in the amount indicated in the table.4. Topped up to the mark with water and mix. 10 cm
of the resulting solutions was placed in six volumetric flasks with a capacity of 1000 cm
, top up each flask to the mark with water and mix.
Table 4
The volume of a standard solution of zinc, cm |
The volume of the background solution of copper, see |
The mass of zinc in 100 cm |
| 0* |
50 |
0 |
| 1 |
50 |
0,025 |
| 2 |
50 |
0,05 |
| 4 |
50 |
0,10 |
| 8 |
50 |
0,20 |
| 12 |
50 |
0,30 |
________________
* Blank sample for calibration.
7.2. Preparation of solution for analysis
7.2.1. Place the sample for analysis (shavings) with a mass of (1±0,0002) g in a Teflon beaker. If heating is carried out in a water bath, you can use the cups made of polypropylene or low density polyethylene.
7.2.2. Add 40 cmof a mixture of acid, cover with a lid and gently heated to dissolve the sample, then heated to a temperature of approximately 90 °C and held until the termination of allocation of steams of nitric oxide. Washed by the water cover and the side of the Cup and cooled.
7.2.3. When the mass fraction of zinc 0,001−0,01% pour the entire solution (p.7.2.2) in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.
7.2.4. When the mass fraction of the zinc of 0.005−0.06% poured all the solution (p.7.2.2) in a volumetric flask with a capacity of 200 cm, made up to the mark with water and mix.
7.2.5. When the mass fraction of zinc is 0.05−0.6% of the entire solution is poured (p.7.2.2) in a volumetric flask with a capacity of 200 cm, made up to the mark with water and mix. Placed 100 cm
of the resulting solution into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
7.2.6. When the mass fraction of zinc of 0.5−6% poured all the solution (p.7.2.2) in a volumetric flask with a capacity of 200 cm, made up to the mark with water and mix. Put 10 cm
of the resulting solution into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
7.3. Spectrometer measurements.
7.3.1. Preparation of the device (see manufacturer’s instructions on features used the optimal settings of the instrument).
Include the electrical system and allow it to warm up. Set a lamp with a zinc hollow cathode and derive analytical line of 213,8 nm. You should adjust the flame air-acetylene torch.
7.3.2. The measurement of the calibration solutions
Put the portions of the calibration solutions in small beakers, and then spray the solutions into the flame. Measures should be taken to ensure that spraying all calibration solutions were constant speed. Record the absorbance of each calibration solution. After spraying of each solution is sprayed a small amount of water in order to clean the burner.
May need amplification if the standard solutions have a minimum zinc content (p.7.1.1).
7.3.3. Construction of calibration curve
Using the measurement results of the calibration solutions to build calibration curve, plotting the abscissa shows the concentration of zinc (mg per 100 cm), and the y — axis the corresponding value of absorbance by subtracting the values of absorbance for each calibration solution, the absorption value of the blank experience.
Note. The calibration curve can be excessive curvature. This curvature can occur when the absorbance at the midpoint is outside 0,55 absorbance of the calibration solution with a maximum content of zinc. If this situation occurs, the calibration solutions should be diluted to a minimum zinc content required for optimal curvature. Solutions for the analysis also need to be diluted in the same proportion.
7.3.4. Measurement solution for analysis
Measure the absorbance of the analyzed solution and the blank sample in the same way as the calibration solutions. Conduct a comparison of the test solutions with the two respective calibration solutions. All measurements are performed in exact sequence and without interruption to minimize fluctuations of the instrumental error.
7.4. Blank sample
The blank sample produced simultaneously with the determination of the sample by the same method using the same quantities of reagents and copper, and in the analysis, but without the sample the sample analyzed.
7.5. A control measurement
Preliminary equipment check is carried out by preparing the standard solution or synthetic solution containing a known amount of zinc and has a composition similar to the analyzed material, and performing the operations given in PP.7.2 and 7.3.
8. Processing of the results
Using the appropriate calibration curve (p.7.3.3) determine the concentration of zinc in solution on the measured absorption.
Mass fraction of zinc in percent is calculated by the formula
where is the mass of sample for analysis, g;
— weight of zinc determined in the blank sample, mg;
— weight of zinc determined in the sample solution, mg;
— the ratio of the volume of the solution in the first flask to volume handled in the second flask;
=1 if in the first flask contains the final solution for testing, i.e. dilution of the solution is performed;
— the volume of the flask containing the final solution for testing, see
.
9. Analysis report
Report on the analysis shall contain:
a) the method of sampling;
b) applied the method of analysis;
C) the results obtained and the method of their calculation;
d) all of the characteristic features observed in the analysis;
d) all of the done operations not covered by this international standard, or considered adverse.
