GOST 18385.4-79
GOST 18385.4−79 Niobium. Methods for determination of tantalum (with Amendments No. 1, 2)
GOST 18385.4−79
Group B59
STATE STANDARD OF THE USSR
NIOBIUM
Method for the determination of tantalum
Niobium. Method for the determination of tantalum
AXTU 1709*
______________
* Introduced advanced Edit. N 1.
Valid from 01.07.1980
before 01.07.1985*
__________________________________
* Expiration removed
Protocol 5−94 N Interstate Council
for standardization, Metrology and certification
(IUS N 11/12, 1994). — Note the manufacturer’s database.
DEVELOPED by the Ministry of nonferrous metallurgy of the USSR
PERFORMERS
A. V. Elyutin, Yu. A. Karpov, A. G. Valkanov, L. N. Filimonov, V. V. Korolev, V. V. Nedler, V. G., Miscreants, T. M. Malyutina, V. M. Mikhailov, E. G. Nembrini
INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
Member Of The Board Of A. P. Snurnikov
APPROVED AND promulgated by the Decree of the State Committee USSR on standards on may 30, 1979 N 1968
INSTEAD 18385.7 GOST-73
The Change N 1, approved and put into effect by the Decree of the USSR State Committee for standards from
Change N 1, 2 made by the manufacturer of the database in the text IUS N 1, 1985, IUS N 3, 1990
This standard specifies the extraction-photometric method for the determination of tantalum (from 0.06 to 0.45%).
The method is based on extraction of fortuntate crystal violet in a mixture of toluene and acetone from sulfate-tartrate environment and fotomaterialy extract.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 18385.0−79*.
_______________
* On the territory of the Russian Federation GOST 18385.0−89, here and hereafter. — Note the manufacturer’s database.
2. APPARATUS, REAGENTS AND SOLUTIONS
Photoelectrocolorimeter FEK-60 or similar type.
Analytical scale.
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 with a capacity of 2−3 cm.
Volumetric flasks with a capacity of 100, 500, 1000 cm.
Measuring cylinders with a capacity of 50, 100 cm.
The quartz crucibles with a capacity of 50 cm.
Pipettes with volume capacity of 1, 2, 5 and 10 cm.
Plastic cans with a capacity of 500 cm.
Paper flat «Phan», pH 0.4 and 1.4 or «Rifai», pH about 0.3−2.2.
Oven muffle.
Tantalum pentoxide-containing basic substance is not less than 99.9%.
The sodium sulfate Piro on the other 6−09−5404−88.
Ammonium vinocity on the other 6−09−08−2007−89, an aqueous solution with a mass fraction of 1%. Solution: a sample of ammonium Vinokurova weight of 100 g was dissolved in 700 cmof hot water, cool and add water to 1 DM
.
Ammonium oxalate according to GOST 5712−78, an aqueous solution with a mass fraction of 10%. Solution: weighed 100 g ammonium oxalate are dissolved in 700 cmof hot water, cool and add water to 1 DM
.
Sulfuric acid GOST 4204−77 and a solution with a concentration of 5 mol/DM. Solution: the water volume 722 cm
carefully poured in small portions with constant stirring 278 cm
of concentrated sulfuric acid. If the mixture is strongly heated, it cooled, and then poured the next portion of acid.
Solution for dilution: sample peacemaking sodium with a mass of 20 g was placed in a crucible and fused in a muffle furnace to remove vapors of sulfuric acid, the melt is dissolved in 200 cmhot Vinokurova ammonium solution with a mass fraction of 10%, flow 100 cm
of water 45 cm
of sulfuric acid solution with molar concentration of 5 mol/DM
, cooled, transferred to a volumetric flask with a capacity of 500 cm
and add to the label values of the pH of the solution 1−1,3.
Ammonia water according to GOST 3760−79 diluted 1:1.
Toluene according to GOST 5789−78.
Acetone according to GOST 2603−79.
Crystal violet, an aqueous solution with a mass fraction of 0.2%, suitable for use in a day after preparation, stored in a flask made of dark glass; solution: a portion of the dye mass 0.2 g is dissolved in water, adding it in small portions, transfer the solution to precipitate in a volumetric flask with a capacity of 100 cm, the volume was adjusted to the mark with water and mix. The solution is kept in a dark place for a day, then filtered through filter «blue ribbon».
Sodium fluoride according to GOST 4463−76, an aqueous solution with a mass fraction of 5%; a sample of sodium fluoride with a mass of 25 g thoroughly mixed with 500 cmof hot water, the solution with the undissolved residue was transferred to a polyethylene jar and left overnight; the supernatant clear solution is decanted into another plastic jar.
Distilled water.
(Changed edition, Rev. N 2).
2.1. Prep
otavka analysis
2.1.1. Preparation of a standard solution and solution A
Standard solution: 0,0610 g of tantalum pentoxide was placed in a crucible and fused at 800 °C With 2 g of sodium peacemaking, going to add 40 cmhot mortar Vinokurova ammonium and boil while stirring until dissolved, adding 10 cm
of an aqueous solution of ammonia. The solution is poured into a measuring flask with a capacity of 100 cm
and then filled to the mark with water; 1 cm
standard solution contains 0.5 mg of tantalum.
Solution a: 2 cmstandard solution is placed in a volumetric flask with a capacity of 100 cm
, the volume was adjusted solution for diluting to the mark; 1 cm
of solution A contains 10 µg of tantalum. Solution And use within 2−3 days after preparation.
2.1.2. Construction of calibration curve
In quartz cylinders with ground stoppers is administered 0,20; 0,40; 0,60; 0,80; 1,0; 1,2; 1,4 and 1.8 cmof solution A. the solution Volume in each cylinder is adjusted with a solution for dilution up to 10 cm
; the pH of the resulting solution should be 1−1,3 (pH is adjusted in a separate aliquot on universal indicator paper; if the pH is not reached, poured dropwise a 10 n solution of sulfuric acid or aqueous ammonia). Then to the resulting solution poured in 9 cm
of toluene and 1 cm
of acetone, 1.8 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 take with a dry pipette with a piston or bag is exactly 7 cm
extract and transferred to a dry test tube with a glass stopper, which had previously added exactly 3 cm
of acetone. The contents of the tube mixed. Do with the contents of each quartz cylinder. The obtained solutions represent working solutions comparison. Before measurement of optical density of solutions can stand for a few hours.
The solutions comparison is sequentially transferred to the cuvette of a photoelectrocolorimeter with a thickness of the light absorbing layer 20 mm and measure the optical density of each solution as indicated in GOST 18385.0−79. The optical density measured at a wavelength of 590 nm filter N 5. As the zero solution is used in water.
At the same time through all the stages of building a calibration chart, hold two parallel reference experiment the purity of the reagents. The value of optical density in the reference experiment is subtracted from the optical density of the solutions comparison. The optical density of the reference experiment shall not exceed 0.0
3.
2.1.1,
2.2. Analysis
0.25 g of niobium was placed in a quartz crucible, fused in a muffle furnace at 800 °C with 5 g of sodium peacemaking and 1−2 cmof sulphuric acid until a clear melt and stop the allocation of sulphuric acid fumes. The fusion is dissolved by boiling in 50 cm
solution Vinokurova ammonium, add 50 cm
of water and 23 cm
5 mol/DM
solution of sulphuric acid. The solution was transferred to a volumetric flask with a capacity of 250 cm
, was adjusted to the mark with water (solution pH should be 1 to 1,3 to set on indicator paper). Pipette select 4 or 5 cm
of the resulting solution (with a mass fraction of tantalum 0,06−0,2% is taken 5 cm
, at a mass fraction of more than 0.2% of selected 4 cm
) and transferred to a quartz cylinder with a glass stopper, and then dilute it to 10 cm
with a solution to dilution; the pH of the resulting solution should be 1−1,3 (pH aliquotes installed in a separate part, if it is not reached — poured dropwise 5 mol/DM
solution of sulfuric acid or aqueous ammonia). Poured to the obtained solution of 9 cm
of toluene and 1 cm
of acetone, 1.8 cm
of a solution of sodium fluoride (plastic pipette) and 1 cm
of a solution of crystal violet and then perform the extraction and measurement of optical density as described under construction of calibration curve in step
At the same time through all stages of the analysis carried out two parallel reference experiment the purity of the reagents. Optical density of the solution in the reference experiment shall not exceed 0,04. From the values of absorbance of the analyzed solution is subtracted the average value of the optical density of the solution in the reference experiment.
A lot of tantalum in the sample solution found by the calibration
graphics.
2.3. Processing of the results
Mass fraction of tantalum () in percent is calculated by the formula
where — weight of tantalum was found in the calibration schedule, mcg;
— volume aliquote part, cm
;
— the weight of the portion,
The difference between the results of two parallel definitions and results of the two tests shall not exceed the allowable absolute values of the differences indicated in the table.
| The mass fraction of tantalum, % | Allowable absolute differences, % |
| 0,06 | 0,02 |
| 0,1 | 0,02 |
| 0,15 | 0,03 |
| 0,2 | 0,04 |
| 0,3 | 0,06 |
| 0,4 | 0,08 |
| 0,45 | 0,09 |
Allowable absolute differences of the intermediate mass fraction of tantalum calculated using linear interpolation.
2.2, 2.3. (Changed edition, Rev. N 1).
2.4. Validation results
The correctness of the results of analysis control method supplements. Aliquoted to three equal parts of one of the analyzed solutions, in each of which the weight of tantalum, mounted on PP.2.2; 2.3, is 6 mcg, add 0.6 cmof solution A. the resulting solutions analyzed for PP.2.2; 2.3. The result of the analysis alikvotnih parts with additives of tantalum taking the arithmetic average of the results of the three definitions (in these three alikvotnih parts). Tests correct when the result obtained differs from the content of tantalum in alikvotnih parts without addition of tantalum is not more than 7 and not less than 5 mg of tantalum. If the result is out of the specified range, the control of correctness of analysis results is repeated, increasing the number of the same alikvotnih parts of one of the analyzed solutions to six. The result should be different from the initial content of tantalum in alikvotnih parts of the solution is not more than 6.9 and less than 5.1 mcg of tantalum.
(Changed edition, Rev. N 1).
3. PREPARATION FOR ASSAY
3.1. Preparation of standard solutions of tantalum
A solution of tantalum (spare) containing 0.5 mg/cm; the weight of tantalum pentoxide weight 0,061 g is placed in a quartz crucible with lid and fused with 4 g of sodium peacemaking in a muffle furnace at a temperature of 850−900 °C until a clear melt, adding in the melting process 1−2 times for 1 cm
of sulfuric acid. The fusion is dissolved by boiling in 40 cm
hot solution of ammonium oxalate with a mass fraction of 10%. The solution was transferred to volumetric flask with a capacity of 100 cm
, adjusted to the mark with water and mix. The solution is ready for use within one month.
A solution of tantalum (work) containing 10 µg/cmof tantalum: 2 cm
fallback solution is placed in a volumetric flask with a capacity of 100 cm
and adjusted to the mark with solution for dilution. The solution is ready within 2−3 days
.
3.2. Construction of calibration curve
In quartz cylinders with ground stoppers is administered 0,20; 0,40; 0,60; 0,80; 1,0; 1,2; 1,4 1.8 cm andthe working solution. The solution volume in each cylinder is adjusted with a solution for dilution up to 10 cm
, the pH value of the resulting solution should be 1−1,3, the pH value of the solution set by adding dropwise a sulfuric acid solution with molar concentration of 5 mol/DM
or ammonia solution, diluted 1:1 (pH of test solution on the indicator paper). Then pour the 9 cm
of toluene and 1 cm
of acetone, 2 cm
of a solution of sodium fluoride and 1 cm
of a solution of crystal violet. The cylinder is stoppered, shaken for 1 min, then leave for 1 min Take with a dry pipette with the piston or pear 7 cm
extract and transferred to a dry glass vial with a ground stopper, to which is previously added with a pipette 3 cm
of acetone, and stirred. Measure the optical density of the solution on the photoelectrocolorimeter using a filter with maximum transmittance at a wavelength of ~590 nm and cuvette thickness of the light absorbing layer of 20 mm in relation to the water.
Through all stages of the analysis carried out control experience in chemicals. The value of optical density in the reference experiment is subtracted from the value of the optical density of the analyzed solution. The optical density of control experience should not exceed a value of 0.03, otherwise changing dishes and reagents.
According to the obtained values of optical density and corresponding mass of tantalum to build the calibration graph.
Section 3. (Added, Rev. N 2).
4. ANALYSIS
A portion of the niobium mass of 0.1 g was placed in a quartz crucible, fused in a muffle furnace at a temperature of 800−850 °C With 4 g of sodium peacemaking and 1−2 cmof sulphuric acid until a clear melt and stop the allocation of sulphuric acid fumes. The fusion is dissolved by boiling in 40 cm
hot Vinokurova ammonium solution with a mass fraction of 10%, add 20 cm
of water and 9 cm
of sulfuric acid solution with molar concentration of 5 mol/DM
. The solution was transferred to a volumetric flask with a capacity of 100 cm
and adjusted to the mark with water.
Aliquot part of the solution, equal to 4 or 5 cm(with a mass fraction of tantalum 0,06−0,2% is taken 5 cm
, at a mass fraction of more than 0.2% of selected 4 cm
), transferred to a quartz cylinder with a glass tube and adjusted to 10 cm
with a solution for dilution. The pH of the resulting solution should be 1−1,3. (The pH of the solution sets, adding drop by drop a solution of sulfuric acid with molar concentration of 5 mol/DM
or ammonia solution, diluted 1:1; pH value of the solution is checked by indicator paper). Then pour the 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 then perform the extraction and measurement of optical density as described in section 3.2.
At the same time through all stages of the analysis carried out two parallel reference experiment the purity of the reagents. Optical density of the solution in the reference experiment must not exceed a value of 0.04. From the values of absorbance of the analyzed solution is subtracted the average value of the optical density of the solution in the reference experiment.
Section 4. (Added, Rev. N 2).
5. PROCESSING OF THE RESULTS
Mass fraction of tantalum () in percent is calculated by the formula
where — weight of tantalum was found in the calibration schedule, mcg;
— the mass of sample, g;
— volume aliquote part, see
.
The difference between the two results of parallel measurements and two test results shall not exceed the allowable absolute values of the differences indicated in the table.2.
Table 2
| The mass fraction of tantalum, % | The absolute allowable difference, % |
| 0,06 | 0,02 |
| 0,10 | 0,02 |
| 0,15 | 0,03 |
| 0,20 | 0,04 |
| 0,30 | 0,06 |
| 0,40 | 0,08 |
| 0,45 | 0,09 |
Section 5. (Added, Rev. N 2).
6. VALIDATION RESULTS
The accuracy of the results of analysis control method supplements.
The Supplement should be 2−3 times greater than the mass fraction of the designated impurities in the sample , while
the lower limit is determined by the mass fraction, the additive should be 2−3 times the value
. Further — GOST 18385.0−79*, p.1.19.
_______________
* On the territory of the Russian Federation GOST 18385.0−89. — Note the manufacturer’s database.
Section 6. (Added, Rev. N 2).
