GOST 23862.30-79
GOST 23862.30−79 Rare-earth metals and their oxides. Method for the determination of tantalum (with Amendments No. 1, 2)
GOST 23862.30−79
Group B59
INTERSTATE STANDARD
RARE EARTH METALS AND THEIR OXIDES
Method for the determination of tantalum
Rare-earth metals and their oxides. Method of determination of tantalum
ISS 77.120.99
AXTU 1709
Date of introduction 1981−01−01
The decision of the State Committee USSR on standards on October 19, 1979 N 3989 date of introduction is established 01.01.81
Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)
EDITION with Amendments No. 1, 2 approved in April 1985, may 1990 (IUS 7−85, 8−90).
This standard sets the photometric method for the determination of tantalum (from 2·10% to 3·10
%) in rare earth metals and their oxides (except cerium and its dioxide).
The method is based on extraction of fortuntate crystal violet in a mixture of toluene and acetone from sulfacetamide environment and subsequent measurement of optical density of the extract. The content of tantalum is found by the calibration schedule.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 23862.0−79.
2. APPARATUS, REAGENTS AND SOLUTIONS
Photoelectrocolorimeter FEK-56, spectrophotometer or similar device.
Muffle furnace with thermostat providing temperatures up to 800 °C.
Tile electric.
The quartz cylinders with ground stoppers with a capacity of 80 cm.
Glass test tubes with ground stoppers with a capacity of 15 cm.
Pipettes made of polyethylene.
Volumetric flasks with a capacity of 100, 200 cm.
Funnels, conical.
Glasses with a capacity of 100, 250 cm.
The quartz crucibles with a capacity of 40−80 cm.
Glass pipettes with a capacity of 1, 5 and 10 cm.
Watch-glasses.
Hydrochloric acid by the GOST 3118−77, H. h., diluted 1:1 and a solution with a mass fraction of 1%.
Tannin (bright) solutions with concentrations of 100 and 5 g/lsolution of hydrochloric acid with a mass fraction of 1%.
Gelatin food according to GOST 11293−89.
Sulfuric acid GOST 4204−77, H. C., 5 mol/DMsolution.
Sodium preservatory for NTD, h. e. a., a solution with a concentration of 40 g/DM.
Ammonium vinocity for NTD, solutions with concentrations of 100 and 40 g/DM.
Ammonia water according to GOST 3760−79, H. h, concentrated and diluted 1:9.
Solution for dilution: 10 g peacemaking sodium, calcined to remove vapors of sulfuric acid, dissolved in 200 cmhot Vinokurova ammonium solution (100 g/DM
), pour 5 cm
of concentrated ammonia, 100 cm
of water 45 cm
5 mol/DM
sulfuric acid and dilute the solution in a volumetric flask with a capacity of 500 cm
to the mark with water (the pH of the solution is equal to 1−1,3).
Toluene according to GOST 5789−78.
Acetone according to GOST 2603−79.
Crystal violet, an aqueous solution with a concentration of 2 g/DM, usable the day after cooking. Can be stored for a long time in a dark place.
Sodium fluoride according to GOST 4463−76, h. e. a., a solution with a concentration of 50 g/DM(saturated); 25 g of sodium fluoride are thoroughly mixed with 500 cm
of hot water. The solution with the residue was transferred to a plastic jar and left overnight. The supernatant clear solution is decanted into another plastic jar.
Tantalum pentoxide with a mass fraction of main substance not less than 99.5%.
Standard solution tantalum (spare) containing 0.5 mg/cmof tantalum: a sample of tantalum pentoxide weight 0,061 g is fused with 2 g of sodium peacemaking. Going to add 40 cm
hot mortar Vinokurova ammonium (100 g/DM
) and boil while stirring until dissolved, gradually adding 10 cm
of ammonia, diluted 1:9. The solution was transferred to volumetric flask with a capacity of 100 cm
and the volume was adjusted solution to the mark with water.
A solution of tantalum (work) containing 10 µg/cmof tantalum, is prepared by diluting the standard fallback solution of tantalum with a solution for dilution of 50 times. Within 2−3 days after preparation.
Sec. 2. (Changed edition, Rev. N 2).
3. ANALYSIS
3.1. A portion of the sample weight 1−2 g (depending on the tantalum content) was dissolved in 20 cmof hydrochloric acid diluted 1:1.
The solution was diluted to ~100 cmwater (small sediment is allowed) heat 3−5 min.
Then poured while stirring 10 cmof a solution of tannin with the concentration of 100 g/DM
, the beaker cover watch glass, heat to boiling and boil for 15−20 minutes while maintaining 110 cm
by the addition of heated water. After cooling, poured 10 cm
of the solution and gelatin solution and the precipitate was allowed to stand for not less than 2−3 hours
The precipitate was filtered off and washed several times with a solution of tannin concentration of 5 g/DM. The filter with precipitate was placed in a quartz crucible, dried, burned, calcined in a muffle furnace at 800 °C and fused with 2 g of sodium peacemaking to obtain a homogeneous melt.
After cooling, the melt is leached 20 cmhot Vinokurova ammonium solution with a concentration of 100 g/DM
with the addition of 10 cm
of ammonia, diluted 1:9.
Solution (volume 50−70 cm) are heated, while stirring, boil for a few minutes and after cooling transferred in a volumetric flask with a capacity of 200 cm
. Pour 20 cm
of Vinokurova ammonium solution with a concentration of 100 g/DM
, 50 cm
peacemaking solution of sodium and the volume was adjusted solution to the mark with water.
Take away 1 cmof the solution, transferred to a quartz cylinder with a ground stopper and diluted to 10 cm
with a solution for dilution, the pH of the solution should be equal to 1−1,3. If the pH of the solution has a different value, it is adjusted to the desired value by dropwise addition of 5 mol/DM
sulfuric acid or ammonia (1:9). To the obtained solution poured 9 cm
of toluene and 1 cm
of acetone, 2 cm
of a solution of sodium fluoride (plastic pipette) and 1 cm
of a solution of crystal violet. The cylinder is stoppered and the contents shaken out with 1 min. After standing for 1 min, pipetted with a piston or pear 7 cm
extract and transferred to a dry test tube with a glass stopper, which had previously entered exactly 3 cm
of acetone, stirred. The optical density measured at
At the same time through all stages of the analysis carried out control experience in chemicals. Optical density of the solution in the reference experiment shall not exceed 0,04, otherwise replace the reagents. The value of optical density in the reference experiment is subtracted from the value of optical density of test solution. A lot of tantalum find in the calibration schedule.
(Changed red
Ktsia, Rev. N 1, 2).
3.2. Construction of calibration curve
In a quartz cylinder with a glass stopper is introduced 0,10; 0,30; 0,50; 0,70; 0,90; 1,10; 1,30; 1,50 cmof a solution of tantalum (containing 10 µg/cm
tantalum) and dilute to 10 cm
solution for dilution with pH equal to 1−1,3. Poured 9 cm
of toluene and 1 cm
of acetone, 2 cm
of sodium fluoride and 1 cm
of a solution of crystal violet. The cylinder is stoppered and the contents shaken out with 1 min. After standing for 1 min take with a dry pipette with the piston or pear 7 cm
extract and transferred to a dry test tube with a glass stopper, which had previously introduced 3 cm
of acetone. The contents of the vial are mixed and transferred to a cuvette thickness of the light absorbing layer 20 mm. the Optical density measured at
In one of the cylinders introduce all reagents, with the exception of tantalum (zero solution). The optical density of the zero solution should not exceed 0,03, otherwise change the container or reagents. The value of optical density of the zero solution is subtracted from the optical densities of standard solutions. The measurement is performed five times of new portions of the solution.
According to the obtained results build a calibration curve, while the ordinate values of the optical density of the solution, and on the x — axis is the mass of tantalum. Individual points of the graph are checked at least once per month.
(Changed edition, Rev. N 2).
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of tantalum () in percent is calculated by the formula
where — weight of tantalum was found in the calibration schedule, mcg;
— the weight of the portion of the sample,
4.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed the values permitted discrepancies listed in the table.
| The mass fraction of tantalum, % |
Allowable difference, % |
2·10 |
5·10 |
4·10 |
1·10 |
8·10 |
2·10 |
1·10 |
2·10 |
2·10 |
4·10 |
3·10 |
6·10 |
