GOST 23862.27-79
GOST 23862.27−79 Rare-earth metals and their oxides. Method of determination of niobium (Change No. 1)
GOST 23862.27−79
Group B59
INTERSTATE STANDARD
RARE EARTH METALS AND THEIR OXIDES
Method for the determination of niobium
Rare-earth metals and their oxides. Method of determination of niobium
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 Change No. 1, approved in April 1985 (IUS 7−85).
This standard sets the photometric method for the determination of niobium (from 1·10
% 1·10
%) in rare earth metals and their oxides except cerium and its dioxide.
The method is based on reaction of niobium with predilatation (PAR) in tetrasociological the environment after preliminary hydrolytic allocation of niobium with tannin in the presence of gelatin.
The contents of niobium find 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-60 or similar device.
Muffle furnace with thermostat providing temperatures up to 800 °C.
Tile electric.
Glasses with a capacity of 250 cm
.
The quartz crucibles.
Burette capacity 5 cm.
The sodium sulfate Piro at the NTD, a solution with a concentration of 60 g/DM.
Ammonium vinocity average NTD, solutions with a concentration of 100 and 20 g/DM.
Ammonia water according to GOST 3760−79 diluted 1:9.
Hydrochloric acid by the GOST 3118−77, diluted 1:1.
Boric acid according to GOST 9656−75.
Tannin (light), solutions with concentrations of 100 and 5 g/DMin 1% hydrochloric acid.
Gelatin solution with a concentration of 10 g/DM.
4-(2-pyridylazo)-resorcinol (PAR) aqueous solution with a concentration of 1.5 g/DM. 0.15 g of the drug is triturated with a glass rod in a glass with 2 cmof water, dilute with water to 50 cm, the solution was transferred to volumetric flask with a capacity of 100 cmand adjusted to the mark with water, are usable within 1 month.
Of niobium pentoxide with a purity not less than 99.5%.
A standard solution of niobium (spare) containing 1 mg/cmNB: the 0,143 g of niobium pentoxide is fused with 4 grams of sodium pyrosulfite. The smelt is dissolved by heating at 40 cmsolution Vinokurova ammonium (100 g/DM) with added 10 cmammonia (1:9). The solution was transferred to volumetric flask with a capacity of 100 cm, the volume was adjusted to the mark with water and mix.
The solution of niobium (working) containing 10 µg/cmniobium, prepared on the day of use by dilution of a backup solution with a solution of ammonium Vinokurova (20 g/DM) 100 times.
Sec. 2. (Changed edition, Rev. N 1).
3. ANALYSIS
3.1. A portion of the analyzed metal with a mass of 0.5−2 g (depending on the content of niobium) placed in a beaker with a capacity of 250 cm, pour 2−3 cmof water, 20 cmof hydrochloric acid diluted 1:1, and dissolved first in cold, and after violent reaction is moderately heated until complete dissolution of the metal. A portion of the analyzed oxides of REE that corresponds to 0.5−2 g of metal was placed in a beaker and dissolved by heating in 20 cmof hydrochloric acid diluted 1:1.
The resulting solution was diluted to 100 cmwith water, add 0.1 g of boric acid, heated to 50 °C and while stirring pour 10 cmof a solution of tannin (100 g/DM); a glass cover watch glass and boil the solution for 20 minutes while maintaining a volume of 110 cmby adding water. After cooling, poured 10 cmof the solution and gelatin solution and the precipitate was allowed to stand for not less than 4−5 h. the Precipitate was filtered through a filter (white ribbon) and washed with cold solution of tannin (5 g/DM). The filter with precipitate was placed in a quartz crucible, dried, incinerated, and calcined in a muffle furnace at 800 °C, the resulting precipitate was fused with 2 g of sodium peacemaking to obtain a homogeneous melt.
After cooling, the melt is leached 20 cmhot Vinokurova ammonium solution (100 g/DM) with added 10 cmammonia diluted 1:9. The cooled solution was transferred to volumetric flask with a capacity of 100 cm, the volume was adjusted to the mark with water and mix.
Select aliquot part of the solution is 15 cm, placed in a volumetric flask with a capacity of 25 cm; add 4 cmof hydrochloric acid diluted 1:1, 2 cmof solution PAIRS, adjusted to the mark with water and mix. After 1 hour measure optical density of solutions on the photoelectrocolorimeter at 
540 nm in a cuvette with the thickness of the light absorbing layer 50 mm, relative to the zero solution. Mass of niobium find gruberova
nome schedule.
3.2. Construction of calibration curve
In a volumetric flask with a capacity of 25 cmis introduced from microburette 0,20; 0,30; 0,50; 1,0; 2,0; 3,0; 4,0 cmworking solution of niobium (containing 10 µg/cmof niobium) is added to 15 cmof Vinokurova ammonium solution (20 g/DM), 4 cmof dilute hydrochloric acid, 2cmof solution PAIRS, adjusted to the mark with a solution of sodium peacemaking and stirred. In one of the flasks poured all reagents with the exception of niobium (zero solution). The measurements were carried out after 1 h, as indicated in paragraph 3.1
.
3.1−3.2. (Changed edition, Rev. N 1).
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of niobium (
) in percent is calculated by the formula
,
where 
is the mass of niobium, 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.
| |
|
Mass fraction of niobium, %
|
Allowable difference, %
|
1·10 |
5·10 |
1·10 |
5·10 |
