GOST 8775.2-87

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  ГОСТ 8775.2-87

GOST 8775.2−87 Li. Method for the determination of sodium, potassium and calcium

GOST 8775.2−87

Group B59

STATE STANDARD OF THE USSR

LI

Method for the determination of sodium, potassium and calcium

Lithium.
Method for determination of sodium, potassium and calcium

AXTU 1709

Valid from 01.07.88
to 01.07.93*
__________________________
* Limit of validity
filmed on the Protocol, the Interstate Council
for standardization, Metrology and certification
(IUS N 2, 1993). — Note the manufacturer’s database.

INFORMATION DATA

1. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 28.09.87 N 3764

2. The term of the first test 1991

The frequency of inspection 5 years

3. REPLACE GOST 8775−75 (sect.3)

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard sets flame photometric method for the determination of impurities of sodium, potassium and calcium (when the mass fraction of sodium from 0.003 to 0.2%, potassium from 0.001 to 0.02%, calcium from 0.005 to 0.05%) to lithium.

The method is based on excitation in the air-acetylene flame emission spectrum of sodium, potassium and calcium and photoelectric registration of the intensities of analytical lines of sodium, potassium and calcium.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 8775.0−87.

2. APPARATUS, REAGENTS AND MATERIALS

The fiery spectrophotometer C-115 or other type with similar or better metrological characteristics.

Laboratory scales according to GOST 24104−80*, of the 2nd accuracy class with the largest weighing limit of 200 g.
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* On the territory of the Russian Federation GOST 24104−2001. — Note the manufacturer’s database.

Quartz glasses according to GOST 19908−80*.
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* On the territory of the Russian Federation GOST 19908−90. — Note the manufacturer’s database.

Acetylene according to GOST 5457−75.

Hydrochloric acid according to GOST 14261−77, OS.CH., or according to GOST 3118−77, distilled in a quartz apparatus.

Methyl red indicator in 0.1% alcoholic solution prepared according to GOST 4919.1−77.

Sodium chloride according to GOST 4233−77.

Potassium chloride according to GOST 4234−77.

Calcium carbonate according to GOST 4530−76.

Strontium nitrate according to GOST 5429−74.

Lithium carbonate, the OS.h.

Carbon tetrachloride according to GOST 20298−74.

Distilled water GOST 6709−72, double-distilled.

3. PREPARATION FOR ASSAY

3.1. Preparation of solutions for calibration and control

3.1.1. Preparation of a 10% solution of strontium

242,0 g of strontium nitrate is weighed with an accuracy of at least 0.1 g, dissolved in water, transferred to a volumetric flask with a capacity of 1 DM, the volume was adjusted solution with water to 1 DMand stirred.

3.1.2. Preparation of the solution of the base 1% strength solution of lithium

The 106.5 g of lithium carbonate are weighed with an error not more than 0.1 g was placed in a beaker with a capacity of 1 DM, pour 200−300 cmof water, add two or three drops of the indicator and poured hydrochloric acid to acid reaction. Cooled to room temperature, the solution was transferred to a volumetric flask with a capacity of 2 DM, the solution was adjusted to the mark with water and mix.

3.1.3. In solutions of bases and strontium to determine the concentration of sodium, potassium and calcium.

For this photometered at the same time solutions for the calibration and the basis of; according to the results of the photometry data to build calibration graphs.

The concentration of sodium, potassium and calcium in the basis determined by linear interpolation.

The concentration of each of the designated impurities in the solution framework shall not exceed 0.0002 g/DM, in the solution of strontium — 0.001 g/DM.

3.1.4. Preparation of the starting solution for calibration

0,0165 g of sodium chloride, 0,7627 g of potassium chloride 0,9987 g of calcium carbonate and 106.5 g of lithium carbonate was placed in a quartz beaker, moistened with water and gently, drop by drop, poured hydrochloric acid until complete dissolution of salts. The solution was transferred to a volumetric flask with a capacity of 2 DM, cooled, the volume was adjusted solution to the mark with water and mix. The starting solution contains 10 g of lithium and 0.2 g of sodium, potassium and calcium in a 1 DM.

3.1.5. Preparation of solutions for calibration

In a volumetric flask with a capacity of 1 DMplaced 1,5; 2,5; 5,0; 12,5; 25,0; 50,0; 100,0 cminitial solution and 8 cmof a solution of strontium, bring the volume of solution in the flasks with a solution of lithium (10 g/DM) up to the mark and mix.

The calibration solutions contain sodium, potassium and calcium (without regard to the content of these elements in the basis) 0,0003; 0,0005; 0,0010; 0,0025; 0,0050; 0,0100; 0,0200 g/DM. The contents of sodium, potassium and calcium in solutions to calibration adjust based on the content of these elements in the basis.

3.2. Preparation of the spectrophotometer

Preparation of the spectrophotometer to the work carried out by the device attached to the user.

3.3. Sample preparation

Pieces of lithium metal stored in accordance with GOST 8774−75, remove the tweezers from the banks, degreased with carbon tetrachloride, cleaned with a knife from the oxides and on the plate of organic glass cut from each piece of the required amount of metal to total mass was approximately 1 g.

4. ANALYSIS

4.1. Weighed samples of lithium with a mass of 1.00 g is dissolved in water, contained in a quartz glass with a capacity of 200 cm, with each piece lithium make glass after dissolution of the previous one, add 1−2 drops of indicator and dropwise poured hydrochloric acid to acid reaction. The sample solution is poured into a measuring flask with a capacity of 100 cm, add 0.8 cmof a solution of strontium, the volume was adjusted solution to the mark with water and mix. When the content in the samples of sodium, potassium and calcium more than 0.5% from the sample solution is diluted with a solution of the bases 10 times. If the aluminum content in the samples less than 0.01%, a solution of strontium in samples and calibration solutions can not be added.

4.2. Prepared to work the spectrophotometer photometric the analyzed sample solution and the corresponding concentrations of the calibration solutions.

Fotometrirovanie solutions is carried out at the analytical line wavelengths listed in table.1.

Table 1

The solutions of samples and standards for calibration photometric three times and the result should be the arithmetic mean value of three measurements.

4.3. The results of the photometry of the calibration solutions to build calibration graphs by laying the abscissa shows the concentration of the element in g/DM, y-axis affimations average value of three measurements of the analytical signal of the calibration solution. For the calibration chart to determine the concentration of sodium, potassium and calcium in the sample (), g/DM.

5. PROCESSING OF THE RESULTS

5.1. Mass fraction of sodium, potassium and calcium () in percent is calculated by the formula

.

5.2. The result of the analysis taking the arithmetic mean of two parallel definitions (some definitions) under the conditions of the PP.2.5, 2.6, and 2.10 GOST 8775.0−87.

5.3. Accuracy metrics

5.3.1. Indicators of convergence and reproducibility of the definitions and shown in table.2.

Table 2

5.3.2. Non-excluded systematic error () is insignificant compared to the random error.

5.3.3. The value of error analysis result () is determined according to GOST 8775.0−87.

5.4. The control accuracy of the analysis

The control accuracy of the analysis carried out by the method of additives in accordance with GOST 8775.0−87, using as additives aliquote part of the calibration mixtures of sodium, potassium and calcium, prepared according to claim 3.1.5. Calibration solution the determined element is added to the weighed sample until it is dissolved.