GOST 17262.4-78
STATE STANDARD OF THE USSR
CADMIUM
METHOD OF SPECTRAL DETERMINATION
ZINC AND IRON
GOST 17262.4−78
USSR STATE COMMITTEE ON STANDARDS
MOSCOW
STATE STANDARD OF THE USSR
CADMIUM Method of spectral determination Cadmium. Method of spectral for the |
GOST |
Resolution of the USSR State Committee on standards dated 29 August 1978. No. 2364 the validity period is set
from
before
(Changed edition, Rev. No. 1, 2).
This standard sets the spectrographic method for the determination of iron and zinc in cadmium in the range of mass fraction of, %:
zinc — 0.0008 to 0.016;
iron — from 0,0002 to 0,006.
This method is used in case of a disagreement in quality assessment.
The basis of spectrographic determination of impurities on the method of «three standards» with the excitation spectrum in the arc mode. Analyzed cadmium metal is previously converted into oxide.
(Changed edition, Rev. No. 1, 2, 3).
1. GENERAL REQUIREMENTS
1.1. General requirements — according to GOST 25086−81.
1.2. Samples for analysis are taken in the form of chips or slices according to GOST 1467−93.
(Changed edition, Rev. No. 1, 3).
2. EQUIPMENT, MATERIALS, SOLUTIONS AND REAGENTS
The diffraction type spectrograph DFS-8 with a diffraction grating 600 lines per millimeter and being an illumination system of the slit.
The generator is activated the arc AC.
Microphotometer of any type, designed to measure pucherani spectral lines (complete set).
Spectromancer of PS-18.
The furnace muffle.
Tile electric.
Libra torsion bar type W with a weighing error of no more than 0.001 g.
Laboratory scales with a weighing error of no more than 0.0002 g:
Cup quartz GOST 19908−90.
Flasks with graduated neck GOST 1770−74.
Pipette, capacity 1.2 cm3.
Nitric acid of high purity according to GOST 11125−78.
Distilled water GOST 6709−72 distilled in a quartz apparatus.
Electrodes of graphite brand high purity 6 mm in diameter with a crater size of 4x4 mm and a through transverse hole with a diameter of 0.8 mm at the bottom of the crater. Contradicted — carbon rod, sharpened to a truncated cone.
Photographic plate for spectrographic types SFC-02, the SFC-03, NT-2SV at the current ND or other type, allowing to obtain the desired sensitivity of the determined elements.
Metalhydrogen developer of the following composition:
metol according to GOST 25664−83 (1,00 ± 0,01) g
hydroquinone according to GOST 19627−74 (5,00 ± 0,01) g
sodium sulfite according to GOST 195−77 or GOST 5644−75 (26,0 ± 0,1) g
sodium carbonate according to GOST 83−79 (20,0 ± 0,1) g
potassium bromide according to GOST 4160−74 (1,00 ± 0,01) g
distilled water GOST 6709−72 to 1000 cm3.
The time of development of photographic plates (7 ± 1) min at a temperature of 18 — 20 °C.
Note. May be used for the developers of a different composition;
The acidic fixer composition:
sodium Chernovetskiy according to GOST 244−76 — 500 g;
ammonium chloride according to GOST 3773−72 — 100 g;
distilled water GOST 6709−72 — 2 DM3.
Cadmium GOST 1467−77 with zinc content of less than 510-4, iron less than 1 10-4%.
Zinc GOST 3640−79.
Iron powder restored brand MLB-1 according to GOST 9849−86.
Graphite powder of high purity according to GOST 23463−79.
Sodium chloride of high purity mark-6−4.
A standard solution containing 10 mg of zinc in 1 cm3.
A standard solution containing 3 mg of iron in 1 cm3.
The samples for constructing the calibration curve. The basis for the preparation of the sample is the oxide of cadmium obtained by dissolving cadmium metal with a zinc content of less than 510-4 iron less than 110-4 % in concentrated nitric acid and calcining the precipitate in a muffle furnace at a temperature of ~ 500 °C. the parent sample containing 0.16% zinc and 0.06% of iron based on the cadmium metal, is prepared as follows. In a quartz Cup with a capacity of 50 ml is placed 5.7 g of cadmium oxide and injected dropwise 0.8 ml of solution A and 1 ml solution B. the Mixture was evaporated, dried on the hotplate and calcined in a muffle furnace at t = 500 °C. Dilution of a primary sample basis 10 times receive the first calibration sample, a serial dilution which is the basis to receive twice the number of working samples with a mass fraction, %
zinc — 0,016; 0,008; 0,004; 0,002; 0,0008;
iron- 0,006; 0,002; 0,001; 0,0005; 0,0002.
Determination of the mass fraction of zinc in cadmium brand Кд2С and iron in cadmium brands Кд2С and Kd2 is carried out according to GOST 12072.2−79 and GOST 12072.3−79.
(Changed edition, Rev. No. 1, 2, 3).
3. ANALYSIS
3.1. A portion of the sample weighing 5 — 6 g washed in ammonia solution, then rinsed with water and transferred to a quartz Cup with a capacity of 50 ml to dissolve in nitric acid. The solution was evaporated and dried under an infrared lamp or hot plate and then calcined in a muffle furnace at 500 °C for 20 — 30 min. From each sample taken at the two sample and conduct chemical preparation method described above.
(Changed edition, Rev. No. 2).
3.2. Prepared analyzed sample and calibration samples are mixed in a ratio of 10:1 with a buffer consisting of graphite powder and 2% sodium chloride, and 100 mg was placed in the craters of graphite electrodes. Graphite electrode pre-calcined in an arc of constant or alternating current power of 10 A for 15 s.
(Changed edition, Rev. No. 3).
3.3. The spectrum of each of the three calibration samples and the spectra of six samples (three from each sample) photographed on diffraction spectrograph of the DFS-8 in the first order in the arc of a DC power of 15 a, with A slit width of 0.015 mm spectrograph using photographic plates. The exposure time of 40 s.
(Changed edition, Rev. No. 1, 2).
4. PROCESSING OF THE RESULTS
4.1. In the spectrogram, using microphotometry measure of the blackening of the following pairs of lines, nm:
334,5 zinc — cadmium 308,27;
iron 302,0 — cadmium 308,27.
According to the measured pochernenija build calibration graphs in the coordinate
ΔS — lgC,
where ΔS = Sl — SCP;
Sl — the blackening line of the designated element;
Sof SR — blackening line item comparison (CD 308,27 nm);
C — mass fraction of the element in the calibration samples.
When constructing the calibration graphs use semi-log paper.
For the calibration chart find the content of zinc or iron. For the results analysis be the arithmetic mean of results of two parallel measurements obtained on the same photographic plate by the three spectrograms each.
Note. When disagreement in assessing the quality of the final result of the analysis be the arithmetic mean of test results obtained on two photographic plates.
(Changed edition, Rev. No. 1, 2, 3).
4.2. The discrepancy between the results of two parallel measurements with a confidence probability P = 0.95 does not exceed the value of permissible differences dn, calculated by the formula:
where is the arithmetic mean of the results of two parallel measurements.
The discrepancy between the results of two tests with confidence probability P = 0.95 does not exceed the value of permissible differences, is calculated according to the formula
where — the average of the two matched analyses.
(Changed edition, Rev. No. 1, 2).
4.3. Control of the correctness of the results of the analysis carried out by playing a mass fraction of iron and zinc in certified mixtures or by comparison with the result of the analysis, obtained according to GOST 12072.2−79 and GOST 12072.3−79.
Certified blend is prepared by introduction of the calculated amount of solution of zinc and iron in the calculated net charge at the designated impurities of oxide of cadmium.
Calcined, carefully ground and averaged mixture after certification by calculation and approval in accordance with established procedure used in the analysis.
The results of the analysis you think is right, if you played mass fraction of a component in a certified blend is different from its certified characteristics in the certificate is not more than half the value of dn.
When checking independent method, the results of the analysis you think is right when the ratio of
where and — mass fraction of the element in the control and controlled methods of analysis, %;
D1 and D2 — permissible divergence of the two results of the analysis in the control and controlled methods of analysis, %.
Control of the correctness of the results of the analysis should be carried out after prolonged breaks in operation, after equipment repair, as well as the replacement of reagents and solutions.
