GOST 23862.34-79
GOST 23862.34−79 Rare-earth metals and their oxides. Method for the determination of phosphorus (Change No. 1)
GOST 23862.34−79
Group B59
INTERSTATE STANDARD
RARE EARTH METALS AND THEIR OXIDES
Method of determination of phosphorus
Rare-earth metals and their oxides. Method of determination of phosphorus
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 phosphorus (from 5·10% 1·10
%) in rare earth metals and their oxides (except cerium and its dioxide).
The method is based on the formation of reduced forms of the molybdophosphoric heterophilically with subsequent measurement of optical density of the solution on a photoelectrocolorimeter.
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 or similar.
Tile electric.
Glasses chemical.
Volumetric flasks.
Watch-glasses.
Hydrochloric acid of high purity according to GOST 14261−77 diluted 1:1.
Distilled water GOST 6709−72, is further distilled in a quartz apparatus.
Ascorbic acid, a solution with a concentration of 20 g/DM(freshly made).
Ammonium molybdate according to GOST 3765−78, a solution with a concentration of 40 g/DM.
Potassium armanavicius, a solution with a concentration of 3 g/DM.
Potassium phosphate according to GOST odnosemjannyj 4198−75.
A standard solution of phosphorus (spare) containing 0.1 mg/cmof phosphorus, is prepared by dissolving 0,0439 mg of single potassium phosphate in water and the volume was adjusted solution to the mark with water in a volumetric flask with a capacity of 100 cm
.
A solution of phosphorus (working) containing 5 µg/cmof phosphorus, prepared by dilution of a standard solution with water to 20 times.
Sec. 2. (Changed edition, Rev. N 1).
3. ANALYSIS
3.1. A portion of the sample oxide of rare earth weight of 2 g or the corresponding amount of metal transferred into the oxide according to GOST 23862.0−79, placed in a beaker with a capacity of 100 cmand dissolved under moderate heating in 25 cm
hydrochloric acid (1:1). The solution is evaporated to dryness, the residue is dissolved in 15 cm
of water with the addition of 3.5 cm
of hydrochloric acid (1:1). The solution was transferred to volumetric flask with a capacity of 25 cm
and the volume was adjusted to the mark with water. Pipetted 1−2. 5 cm in
solution and transferred to another volumetric flask with a capacity of 25 cm
. The solution is poured into 0.6 cm
of a solution of ammonium molybdate, wash the neck of the bulb 3 cm
of water and then pour the 1.2 cm
of the ascorbic acid solution and 0.2 cm
of a solution of potassium Armenonville. After each addition of the reagent contents of the flask stirred with a rotary motion. Further, the volume of the solution was adjusted to the mark with water, close the neck of the bulb with a piece of tracing paper and carefully mix. After 5 min measure the optical density of a solution on photoelectrocolorimeter at
Solution comparison, to the remaining in a volumetric flask of the solution REE (12.5 cm) flow 1.2 cm
of ascorbic acid solution and adjusted to the mark with water (for analysis of oxides unpainted REE as a solution comparison can be used water).
Simultaneously with the analysis of the sample carried through all stages of control experience on the reagents. The mass of phosphorus in a control experiment should not exceed 0.5 mg.
A lot of phosphorus is determined by the calibration
graphics.
3.2. Construction of calibration curve
In a volumetric flask with a capacity of 25 cmis administered at 0,10; 0,30; 0,50; 1,0; 2,0 cm
of a solution of phosphorus containing 5 µg/cm
of phosphorus, flow 15 cm
of water, 1.7 cm
of hydrochloric acid diluted 1:1, 0.6 cm
of a solution of ammonium molybdate, wash the neck of the bulb 3 cm
of water. Next, in a flask pour the 1.2 cm
of the ascorbic acid solution and 0.2 cm
of a solution of potassium Armenonville. After each addition of the reagent contents of the flask stirred with a rotary motion. Further, the volume of the solution was adjusted to the mark with water, close the neck of the bulb with a piece of tracing paper and carefully mix. After 5 min measure the optical density of solutions on the photoelectrocolorimeter at
According to the obtained values of optical density calibration curve building, causing the y-axis the value of the optical density of the solution, and on the x — axis is the mass of phosphorus.
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of phosphorus () in percent is calculated by the formula
where is the mass of phosphorus in aliquote part of the sample solution, µg;
— the mass of phosphorus in a control experiment, µg;
— the mass of the sample in aliquote part of the solution,
The result of the analysis take the average of results of two parallel measurements.
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 phosphorus, % |
Allowable difference, % |
5·10 |
5·10 |
1·10 |
8·10 |
3·10 |
2·10 |
5·10 |
3·10 |
1·10 |
5·10 |
