GOST 20997.5-81
GOST 20997.5−81
INTERSTATE STANDARD
THALLIUM
METHOD OF CHEMICAL-SPECTRAL DETERMINATION OF TIN
The official Islande
BL 6−99
IPK PUBLISHING house of STANDARDS, Moscow
UDC 669.873:546.811.06:006.354 Group B59
INTERSTATE S T, A N D, A R T
THALLIUM
GOST
20997.5−81*
Method of chemical-spectral determination of tin
Thallium.
Method of chemical-spectral determination of tin AXTU 1709
GOST 20997.5−81 C. 2
The acid chloride.
Sodium iodide according to GOST 8422−76 and solutions I and 0.05 M.
Benzene according to GOST 5955−75.
The aqueous ammonia of high purity according to GOST 24147−80.
Oxalic acid according to GOST 22180−76.
Photographic plates «spectrographic» type II.
Developer a metol-hydrochinone.
Fixer is acidic.
Solution India 10%: a portion of India with a mass of 5.0 g is dissolved in 12 cm1 nitric acid, cooled and transferred to volumetric flask with a capacity of 50 cm3.
A solution of tin 0.1%: suspension of fine Olopa a mass of 0.100 g was dissolved in 2 cm3 of nitric acid. After moving the entire tin in metalogeny acid to the beaker was added 20 cm3 of water and 4.0 g of oxalic acid. The solution was transferred to a volumetric flask with a capacity of 100 cm3. The glass is washed several times with water until complete dissolution of oxalic acid. Slipout the washings in the same volumetric flask and bring to mark with water.
Solution a: 10 cm3 of a 0.1% strength solution of tin is transferred to a volumetric flask with a capacity of 100 cm3 and diluted to the mark with water.
1 cm3 of solution contains 0.1 mg of tin.
Solution B: 10 cm3 solution, And transferred to a volumetric flask with a capacity of 100 cm3 and diluted to the mark with water.
1 cm3 of a solution containing 0.01 mg of tin.
Solution In 10 cm3 of a solution transferred to a volumetric flask with a capacity of 100 cm3 and diluted to the mark with water.
1 cm3 of solution contains 0.001 mg of tin.
Standard solutions of S and prepared on the day of use.
Samples of comparison, with a mass fraction of tin MO-4; 2 I0-4; 3 10~2; MO-3; 3 10 3 %\ is prepared simultaneously with the analyzed samples.
Note. Allowed the use of devices with photoelectric registration of spectrum and other spectrographic equipment and facilities other materials and reagents subject to receipt of the accuracy characteristics as specified in this standard.
Section 2. (Changed the wording. Izm. No. 1, 2).
1
ANALYSIS
3.1. A portion of the metal thallium in a mass of 3.0 g was placed in a beaker with a capacity of 100 cm3 and dissolved by heating p 15 cm3 of a solution of sulfuric acid (1:2). Beaker cover watch glass. At the last moment dissolved add one drop of nitric acid. The solution is cooled to a temperature of 50−60 ° C. add 30 cm3 of water and 25 cm3 of 1 M solution of sodium iodide with stirring. The solution continued to stir for another 2.5 and 3.0 min. the precipitate of iodide of thallium in orange yellow color was filtered through a paper filter. The beaker and the filter washed with 10 cm3 of 0.05 M solution of sodium iodide. The filtrate and washings combined in a separating funnel with a capacity of 200 cm3, heated to a temperature of 35−40 *C, add 10 cm3 of perchloric acid, 30 g of sodium iodide and mix thoroughly. Add 10 cm3 of benzene and shaken for 1 min. After separation the aqueous layer is discarded and the upper organic through the throat of the funnel is transferred into a Cup, to which add 2 cm1 benzene after washing the separating funnel.
In a Cup make I cm3 of solution India. The benzene is evaporated at a temperature of 40 *C (30−40 min) and the concentrate of tin Coosada with the hydroxide India, what to India labatut nitrate solution dropwise with stirring a glass Pato? ka 20 drops of ammonia to a strong smell. The resulting hydroxide dried under a lamp, on a hotplate, and then pumped in a muffle furnace at a temperature of 350 to 400 *C for 30 min. After prokashani obtained oxide India crushed quartz with the pestle to a fine grist, and transmitted to a spectrographic analysis.
Enrichment of lead from the four batches. At the same time to check the purity of reagents used spend control experience.
2
In parallel with the analyzed sample. mi to spectrographically prepare samples comparison. For this five glasses with a capacity of 100 cm3 hurt weighing 0.2−0.5 g sample of thallium containing tin of 1 at least 10~s %. In glasses nakatyvaet respectively 0.1: 0,2; 0.3; 1.0 and 3.0 cm3 solution Q. what per 100 mg India meets MO-4; 2)-4; 310"4; 1 10_3 3 and 10~3%
C. 3 GOST 20997.5−81
tin in concentrate. In each glass add 1 cm3 solution of sulphuric acid (1:2) and under the watch glass, the contents of the beaker are transferred into the solution. At the last moment dissolved add one drop of nitric acid and further analysis are as under sample preparation.
3.2. The obtained concentrates of samples comparison reference experiment and samples of 45 mg will prevent the craters of graphite electrodes (anodes) with a diameter and a depth of 4 mm and burn in the arc of a DC power of 15 L for 3 min (to burnout). The spectra photographed with a diffraction spectrograph of the DFS-8 on photos of type II: width of the slit of a spectrograph 0.020 mm, distance between electrodes of 2.5 to 3.0 mm should be maintained throughout the exposure. Each photographic plate is photographed koncertov spectra of samples comparison at two times, and the spectra of the concentrates of the samples and control experiments for four times.
Section 3. (Changed edition, Rev. No. 1, 2).
4. PROCESSING OF THE RESULTS
4.1. On the spectrogram with the aid of microphotometer measure the blackening of the lines of the tin with a wavelength 283.99 them and the surrounding background. Grigorovichi build graphics in the coordinates D — IgC, where AS = 5, d, f —
For the calibration chart to find the mass fraction of tin in concentrate samples (and the reference experiment (S).
Mass fraction of tin in the sample (L) in percent is determined by the formula
S — P. 100
X=-1-,
t
where 100 is the mass of the obtained concentrate, mg;
t — the weight of the portion of the sample of thallium, taken for analysis, mg.
For constructing a calibration curve allowed to use semilog paper.
The relative standard deviation of repeatability of the results of parallel measurements does not exceed 0.15.
4.2. Discrepancies in the results of four parallel samples (d). as well as the discrepancies of the results of the two analyses (D) shall not exceed the values given in the table (R= 0,95).
| M associe proportion of tin. | The divergence of the four results of the parallel definitions «v | The discrepancy between the results of two tests. % |
| 3−10 11 | 1.5 10 „ | 2−10“ 6 |
| <И0-S | 3−10"6 | 410"6 |
| M0-* | 5 10-6 | 6 10-s |
| 2 10* 5 | 7 u-6 | 9 10-6 |
| 410"4 | 2−10-5 | 210» 5 |
| 8−10"4 | 3−10"* | 4−10 3 |
| Ы0"4 | 4 10-5 | 510-5 |
Permitted discrepancies for the intermediate mass fraction calculated using linear interpolation.
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