GOST 23862.24-79

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  ГОСТ 23862.24-79

GOST 23862.24−79 Rare-earth metals and their oxides. Methods for determination of iron and copper (with Amendments No. 1, 2)

GOST 23862.24−79

Group B59

INTERSTATE STANDARD

RARE EARTH METALS AND THEIR OXIDES

Methods for determination of iron and copper

Rare-earth metals and their oxides. Methods of determination of iron and copper

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 specifies the extraction-photometric method for the determination of iron and copper (at a mass fraction of 5·10% to 5·10%) in rare earth metals and their oxides; extraction-photometric method for the determination of copper (at a mass fraction of 5·10% to 5·10%) in the lanthanum and its oxides; the photometric method for the determination of iron (at mass fraction of 5·10% 1·10%) in Lantana, yttria and their oxides; the photometric method for the determination of iron (at mass proportion of from 1·10% 1·10%) in rare earth metals and their oxides (except cerium and its dioxide).

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 23862.0−79.

EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF IRON AND COPPER TO RARE EARTH METALS AND THEIR OXIDES

The method is based on extraction concentration and separation of impurities of iron and copper with subsequent photometric determination of iron in a thiocyanate, copper in the form of diethyldithiocarbamate.

The mass fraction of iron and copper find for the calibration schedule.

(Changed edition, Rev. N 1).

2. APPARATUS, REAGENTS AND SOLUTIONS

Photoelectrocolorimeter FEK-56 or similar device.

Tile electric.

Apparatus quartz distillation.

Measuring cylinders with a capacity of 5, 10 and 25 cm.

Volumetric flasks with a capacity of 100, 500 and 1000 cm.

Separating funnel with a capacity of 50 and 75 cm.

Conical flasks with a capacity of 50 cm.

Pipettes with a capacity of 1, 2, 5, 10 cm.

Glasses chemical glass with a capacity of 75 cm.

Watch-glasses with a diameter of 30 mm.

The quartz Cup with a capacity of 40 cm.

Amyl ether acetic acid (amylacetate), CH.

The chloroform series 490671, medical.

Acetone according to GOST 2603−79, OS.h.

Ammonia water according to GOST 3760−79, OS.h.

Hydrochloric acid according to GOST 14261−77, OS.h. 20−4, a density of 1.19 g/cmand diluted 4:1.

Nitric acid of high purity according to GOST 11125−84, density 1.4 g/cm, distilled in a quartz apparatus.

The iron powder according to GOST 9849−86.

Electrolytic copper powder according to GOST 4960−75.

Aluminium chloride according to GOST 3759−75, h.d. a.

Hydrogen peroxide according to GOST 10929−76, OS.CH., 30% solution.

Ammonium radamisty, H. h without iron or hç additionally, the purified solution with a concentration of 600 g/DM: 200g Rodenstock ammonium dissolved in 100 cmof water, add 50 mg of aluminum chloride and a few drops of ammonia (before the deposition of hydrates), stirred and allowed sediment to settle for 2−3 h. the Solution was filtered through a filter with a blue ribbon, discarding first portion of filtrate is then evaporated to such a state that a drop deposited on a watch glass, froze. The solution was then cooled, filtered and dried crystals at a temperature of 30−40 °C.

Lead diethyldithiocarbaminate, h, a solution with a concentration of 1.2 g/lin chloroform.

Water, or deionized double-distilled water.

Standard solution of iron (spare) containing 0.1 mg/cmiron: a suspension of iron powder with a mass of 0.1 g was placed in a beaker with a capacity of 100 cm, add 20 cmof concentrated hydrochloric acid and 1 cmof nitric acid and heated until complete dissolution of the sample. After cooling, the solution is transferred into a measuring flask with volume capacity of 1000 cmand dilute to the mark with water.

Solution of iron containing 0.01 mg/cmof iron, is prepared by dilution of a standard solution of iron by water 10 times.

A standard solution of copper (spare) containing 0.1 mg/cmcopper: a sample of copper powder with a mass of 0.05 g was placed in a beaker with a capacity of 50 cmand add 5 cmof concentrated nitric acid. After complete dissolution of the copper solution is transferred to a volumetric flask with a capacity of 500 cmand was adjusted to the mark with water.

A copper solution containing 0.01 mg/cmcopper, is prepared by diluting the original standard (spare) copper solution with water in 10 times.

Sec. 2. (Changed edition, Rev. N 1).

3. ANALYSIS

3.1. Dissolution samples

A portion of the sample with a mass of 0.05−2 g (depending on expected concentration of iron and copper) is placed in a conical flask, poured 0.1 cmof hydrogen peroxide, 10 cmof hydrochloric acid (4:1), cover with a watch glass and dissolved under heating.

A sample of cerium dioxide with a mass of 0.1−2 g (depending on the content of iron and copper) was placed in a quartz Cup, moistened with 0.5 cmof water, pour 5 cmof concentrated nitric acid, 7 cmof hydrogen peroxide, cover with a watch glass and dissolved under heating. The solution is evaporated to a syrupy condition; poured three times for 10 cmof hydrochloric acid (4:1) and evaporated to a syrupy condition.

Then to the resulting solution poured 2−3 drops of ammonia and boil the solutions for the destruction of hydrogen peroxide. The solutions were cooled to room temperature and added to 10 cmof concentrated hydrochloric acid

.

3.2. The determination of iron

The sample solution is transferred to a separatory funnel with a capacity of 50 cm, flow 10 cmof amylacetate funnel and shake for 0.5 min After delamination (lower) aqueous layer transferred into a clean beaker and left to the determination of copper (solution 1).

The organic layer (extract-iron) washed twice with hydrochloric acid, diluted 4:1, portion of 5 cm, the washing solutions are discarded. Then to extract iron added 9 cmof water and extragere iron, shaking the solution in separating funnel for 0.5 min, the Aqueous layer (bottom) was transferred to cuvettes for photometry (50 mm) was added 12 cmof acetone, 1.5 cmRodenstock solution of ammonia and stirred with a glass rod. Optical density of the solution is measured on a photoelectrocolorimeter (490 nm). A solution of comparison used water. Simultaneously conduct control experience through all stages of the analysis and impose on it the amendment. Mass fraction of iron in the sample is determined by calibration curve

.

3.3. Determination of copper

Solution 1 diluted with an equal volume of water, transferred to a separatory funnel with a capacity of 75 cm, add 13 cmof a solution of lead diethyldithiocarbamate in chloroform and shake the funnel for 1 min. After separation the organic layer (lower) was transferred in a dry cell for photometry (30 mm) and measure the optical density of a solution compared to the chloroform on the photoelectrocolorimeter (440 nm). Simultaneously conduct control experience through all stages of the analysis and introduce the amendment. Mass fraction of copper in the sample determined by the calibration schedule.

3.4. Construction of calibration curve

In a separating funnel with a capacity of 50 cmis administered at 20 cmof hydrochloric acid (4:1) and 0,1; 0,2; 0,5; 0,7; 1,0 cmsolutions of iron and copper, which corresponds to 1, 2, 5, 7, 10 µg of each of the elements. Further analysis is carried out on PP.3.2 and 3.3. Build calibration graphs of the dependence of optical density on the mass of iron and copper.

A single point calibration curve check along with the analysis of samples at least once per month.

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of iron or copper (a) percentage calculated by the formula

,

where is the mass of iron or copper, found in the calibration schedule, mcg;

 — the weight of the portion of the sample,

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

4.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed values of allowable differences specified in table.1.

Table 1

4A. EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF COPPER IN LANTHANUM AND ITS OXIDES

The method is based on the extraction concentration of copper in the form of diethyldithiocarbamate with subsequent spectrophotometric determination.

4A.1. Apparatus, reagents and solutions

Spectrophotometer firm «Pye Unicum model» SP 8−100 or similar device.

Apparatus quartz distillation.

Oven electric.

Measuring cylinders with a capacity of 10 and 25 cm.

Volumetric flasks with a capacity of 50, 100, 500 and 1000 cm.

Separating funnel with a capacity of 50 and 75 cm.

Conical flasks with a capacity of 50 cm.

Pipettes with a capacity of 1, 2, 5, 10 cm.

Glasses chemical glass with a capacity of 75 cm.

Watch-glasses with a diameter of 30 mm.

Hydrochloric acid of high purity according to GOST 14261−77, OS.h. 20−4, a density of 1.19 g/cmand diluted 4:1 and 1:1.

Nitric acid of high purity according to GOST 11125−84, density 1.4 g/cm, distilled in a quartz apparatus.

Chloroform medical.

Lead diethyldithiocarbaminate, h, a solution with a concentration of 1.2 g/lin chloroform.

Electrolytic copper powder according to GOST 4960−75.

A solution of copper (spare) containing 0.1 mg/cmcopper: a sample of copper powder with a mass of 0.05 g was placed in a beaker with a capacity of 50 cmand pour 5 cmof concentrated nitric acid. After complete dissolution of the copper solution is transferred to a volumetric flask with a capacity of 500 cmand was adjusted to the mark with water.

A solution of copper work, containing 0.001 mg/cmcopper, is prepared by dilution of the source (reserve) copper solution with water to 100 times. The solution is prepared the day of use.

4A.2. Analysis

4A.2.1. A portion of the lanthanum oxide or 0.5 to 3 g (depending on the expected concentration of copper) is placed in a conical flask, poured 15 cmof hydrochloric acid (4:1), cover with a watch glass and dissolved under heating.

The solution was cooled to room temperature and add 20 cmof hydrochloric acid (1:1).

The solution was transferred to a separatory funnel, add 13 cmof lead diethyldithiocarbamate in chloroform and shake the funnel for 1 min. After separation the organic layer (lower) was transferred in a dry cell for photometry (40 mm) and measure the optical density of a solution compared to the chloroform on the spectrophotometer (435). Simultaneously conduct control experience through all stages of the analysis and introduce the amendment. Mass fraction of copper in the sample determined by the calibration schedule.

4A.2.2. To build a calibration curve in a separating funnel with a capacity of 50 cmis administered at 20 cmof hydrochloric acid (4:1) and 0,15; 0,3; 0,5; 0,7; 1,0 cmworking solution of copper, which corresponds to 0,15, 0,3, 0,5, 0,7 and 1 mcg of copper. Added to 13 cmof a solution of lead diethyldithiocarbamate in chloroform and shake the funnel for 1 min. After the separation of the organic layer (bottom) of the first funnel is transferred to a dry cell for photometry (40 mm) and measure the optical density of a solution compared to the chloroform on the spectrophotometer (435 nm). Then just measure the optical density of the organic layer from the second and all subsequent funnels and build a calibration graph of optical density by weight of copper.

A single point calibration curve check along with the analysis of samples at least once per month.

4A.3. Processing of the results

Mass fraction of copper () in percent is calculated by the formula

,

where is the mass of copper was found in the calibration schedule, mcg;

 — mass of test portion, g.

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed the values of permissible differences given in table.1A.

Table 1a

Sec. 4A. (Added, Rev. N 2).

5. PHOTOMETRIC METHOD FOR DETERMINATION OF IRON IN LANTANA, YTTRIA AND THEIR OXIDES

The method is based on formation of colored complex of iron with fenantrolina and the measurement of its optical density.

5.1. Apparatus, reagents and solutions

Analytical scales ADV-200 or similar.

Photoelectrocolorimeter FEK-56-M or similar device.

A hydrometer with a scale of 1.25 to 1.30 g/cm.

Oven electric.

Quartz distillation apparatus.

Glasses chemical glass with a capacity of 100, 150, 1000 cm.

Volumetric flasks with a capacity of 50 and 1000 cm.

Pipettes with a capacity of 1, 2, 5, 10 cm.

Paper display «of the Congo».

-fenantrolin, h, a solution with a concentration of 2 g/DM.

Water bidistilled.

Hydrochloric acid according to GOST 14261−77, OS.h. 20−4, a density of 1.19 g/cmand diluted 1:1.

The technical rectified ethyl alcohol GOST 18300−87, distilled.

Hydroxylamine hydrochloride according to GOST 5456−79, h. d. a. (recrystallized) solution with a concentration of 100 g/DM.

The recrystallization of hydroxylamine hydrochloride is carried out as follows: prepared by heating saturated water solution, to the solution is added a double volume of alcohol. Precipitated crystals filtered off by suction, the mother liquor on a vacuum filter, then dried between ashless filtrates the air and placed in a flask with a glass stopper.

Sodium acetate 3-water according to GOST 199−78, H. C., recrystallized, an aqueous solution with a concentration of 100 g/DM. The recrystallization is performed as follows: dissolve 500 g of the salt in 350 cmof hot water and the hot solution is filtered through a paper filter, previously washed with distilled ethyl alcohol. The filtrate is evaporated in a water bath at a temperature of 65−70 °C to a density of 1.27−1.28 g/cm(control a hydrometer), cooled to a temperature of 20 °C. the Precipitated crystals are sucked off on a Buchner funnel, washed with a small amount of water and dried at room temperature.

The iron powder according to GOST 9849−86.

Standard solution of iron (spare) containing 1 mg/cmiron: a suspension of iron powder weighing 0.2 g was placed in a beaker with a capacity of 100 cm, pour 2−3 cmof distilled water and 10 cmof hydrochloric acid diluted 1:1. The dissolution is carried out at slow heating. The solution was cooled, transferred to a volumetric flask with a capacity of 200 cmand adjusted to the mark with distilled water.

Solution of iron containing 0.01 mg/cmiron: 1 cmbackup solution is placed in a volumetric flask with a capacity of 100 cm, was diluted to the mark with distilled water and

mix.

5.2. Analysis

5.2.1. A portion of sample weighing 0.5−5 g depending on the content of iron is placed in a beaker with a capacity of 150 cm, flow 10−20 cmof hydrochloric acid (1:1) and heated to dissolve sample. The solution is evaporated to wet salts.

Salt dissolved in 10−15 cmof water and the solution quantitatively transferred to a volumetric flask with a capacity of 50 cm. Pour 2 cmof a solution of hydroxylamine, and after 10 min a solution of sodium acetate until the color transition idicating paper from blue to pink. Then pour 2 cmof sodium acetate, 5 cmsolution -fenantrolina, made up to the mark with water, mix thoroughly and after 45 min, measure the optical density of the solution at a wavelength of 440 nm in a cuvette with optical path length of 50 mm.

At the same time through all stages of the analysis carried out two parallel reference experiment the purity of the reagents. The average value of optical density in the reference experiment is subtracted from the optical density of the solutions comparison. A solution of comparison used water

.

5.2.2. To build a calibration curve in a volumetric flask with a capacity of 50 cmplaced on 0,2; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0 cmof a solution of iron, containing 0.01 mg/cmiron, 10−15 cmof distilled water, and then do as specified in clause 5.2.1, beginning with the words: «Pour 2 cmof a solution of hydroxylamine». After addition of each reagent the contents of the flask should be stirred. According to the obtained values of optical densities and their corresponding masses of iron to build the calibration graph.

5.3. Processing of the results

5.3.1. Mass fraction of iron () in percent is calculated by the formula

,

where  — the weight of the portion of the sample, g;

 — the mass of iron in the sample solution found by the calibration schedule, mg.

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

5.3.2. Discrepancies in the results of two parallel measurements or test results shall not exceed the values of permissible differences given in table.2.

Table 2

Sec. 5. (Added, Rev. N 1).

5A. PHOTOMETRIC METHOD FOR DETERMINATION OF IRON IN RARE-EARTH METALS AND THEIR OXIDES (EXCEPT CERIUM AND ITS DIOXIDE)

The method is based on formation of colored complex of iron and -fenantrolina and the measurement of its optical density.

5A.1. Apparatus, reagents and solutions

Firms spectrophotometer Pye Unicum model SP 8−100 or similar device.

Analytical scale.

A hydrometer with a scale of 1.25 to 1.30 g/cm.

Apparatus quartz distillation.

Oven electric.

Volumetric flasks with a capacity of 50 and 1000 cm.

Pipettes with a capacity of 1, 2, 5, 10 cm.

Glasses chemical glass with a capacity of 100, 150 and 1000 cm.

Paper display «of the Congo».

-fenantrolin, h, a solution with a concentration of 2 g/DM.

Water bidistilled.

Hydrochloric acid of high purity according to GOST 14261−77, OS.h. 20−4, a density of 1.19 g/cmand diluted 1:1.

The technical rectified ethyl alcohol GOST 18300−87, distilled.

Hydroxylamine hydrochloride according to GOST 5456−79, h. d. a. (recrystallized) solution with a concentration of 100 g/DM(preparation of the solution according to GOST 23862.24−79, sec. 5).

Sodium acetate according to GOST trekbody 199−78, H. h, solution with a concentration of 100 g/DMis prepared according to GOST 23862.24−79, sec. 5.

The iron powder according to GOST 9849−86 (preparation of standard iron solution — according to GOST 23862.24−79, sec. 5).

5A.2. Analysis

5A.2.1. A portion of sample weighing 0.5−5 g depending on the mass fraction of iron is placed in a beaker with a capacity of 150 cm, flow 10−20 cmof hydrochloric acid (1:1) and heated to dissolve sample. The solution is evaporated to wet salts.

Salt dissolved in 10−15 cmof water and the solution quantitatively transferred to a volumetric flask with a capacity of 50 cm.

Pour 2 cmof a solution of hydroxylamine and after 10 min a solution of sodium acetate until the color change of the indicator paper from blue to pink. Then pour 2 cmof a solution of sodium acetate, 5 cmsolution -fenantrolina, made up to the mark with water, mix thoroughly and after 45 min, measure the optical density of the solution at a wavelength of 510 nm in a cuvette with optical path length of 40 mm. the Measurement of the optical density of the solution is carried out compared to the colored solution obtained by dissolving the sample. At the same time through all stages of the analysis carried out two parallel reference experiment the purity of the reagents. As a solution comparison in this case, use distilled water.

5A.2.2. To build a calibration curve in a volumetric flask with a capacity of 50 cmplaced on 0,2; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0 cmof a solution of iron, containing 0.01 mg/cmiron, 10−15 cmof distilled water. Pour 2 cmof a solution of hydroxylamine and after 10 min a solution of sodium acetate until the color change of the indicator paper from blue to pink. Then pour 2 cmof a solution of sodium acetate, 5 cmsolution -fenantrolina, made up to the mark with water, mix thoroughly and after 45 min, measure the optical density of the solution at a wavelength of 510 nm in a cuvette with optical path length of 40 mm.

As a solution comparison in this case, use distilled water. According to the obtained values of optical density calibration curve building.

5A.3. Processing of the results

5A.3.1. Mass fraction of iron () in percent is calculated by the formula

,

where is the mass of iron in the sample solution found by the calibration schedule, mg;

 — the mass of iron in solution in the reference experiment, mg;

 — the weight of the portion of the sample,

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

5A.3.2. The discrepancy between the results of two parallel measurements or test results shall not exceed the values of permissible differences given in table.2A.

Table 2A

Sec. 5A. (Added, Rev. N 2).

6. PHOTOMETRIC METHOD FOR DETERMINATION OF IRON IN LANTHANUM, GADOLINIUM, TERUI, DYSPROSIUM, HOLMIUM, TULIYA, YTTERBIUM, OF LUTETIA, ITREE AND THEIR OXIDES

The method is based on formation of colored complex of iron with thiocyanate-ion in nitric acid medium and measurement of its optical density.

6.1. Apparatus, reagents and solutions

Photoelectrocolorimeter FEK-56 or similar.

Oven electric.

The chemical glasses with a capacity of 50, 250 cm.

Volumetric flasks with a capacity of 50, 100, 200 cm.

Hydrochloric acid by the GOST 3118−77, H. h., diluted 1:1.

Potassium rodanistye according to GOST 4139−75, H. h, solution with a concentration of 500 g/DM.

Sulfuric acid of high purity according to GOST 14262−78 diluted 1:5.

The iron powder according to GOST 9849−86.

Nitric acid of high purity according to GOST 11125−84 freed from oxides of nitrogen by boiling before bleaching and diluted 1:1.

Standard solution of iron (spare) containing 1 mg/cmiron: a suspension of iron powder weighing 0.2 g was placed in a beaker with a capacity of 100 cm, pour 2−3 cmof distilled water and 10 cmof hydrochloric acid diluted 1:1. The dissolution is carried out at slow heating. The solution was cooled, transferred to a volumetric flask with a capacity of 200 cmand adjusted to the mark with distilled water. Solution of iron containing 0.01 mg/cmiron: 1 cmbackup solution is placed in a volumetric flask with a capacity of 100 cm, add 10−15 drops of sulfuric acid, diluted 1:5, adjusted to the mark with distilled water, peremeci

vayut.

6.2. Analysis

6.2.1. A portion of the metal or oxide of rare earth elements by mass 0.2−1.0 g were placed in a glass with a capacity of 50 cm, moistened with water, poured 5cmof hydrochloric acid diluted 1:1, dissolved by heating to 70−80 °C, is evaporated to wet salts, cooled to room temperature, poured 4 cmof nitric acid, diluted 1:1, heated to dissolve the salts, transferred to a volumetric flask with a capacity of 50 cm, flow up to 40 cmof water, mix. Before measuring the optical density of the solutions poured 2cmof a solution of potassium Rodenstock, adjusted to the mark with water, mix. The optical density of solutions measured at a wavelength of 490 nm in a cuvette with optical path length of 50 mm as solution, comparison, use water.

At the same time through all stages of the analysis carried out control experience in chemicals, the value of optical density which is subtracted from the value of the optical density of the sample solution. The value of the optical density of the solution in the reference experiment should not be more than 0.05. Otherwise, replace the reagents and the analysis repeated. The mass of iron found by the calibration schedule.

6.2.2. To build a calibration curve in a volumetric flask with a capacity of 50 cmflow 0,0; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution of iron, containing 0.01 mg/cmiron, water up to 40 cm, with 4 cmof a solution of nitric acid, diluted 1:1, mix. Before measuring the optical density of the solutions poured 2cmof a solution of potassium Rodenstock, adjusted to the mark with water, mix. The optical density of solutions measured at a wavelength of 490 nm in a cuvette with optical path length of 50 mm. as a solution comparison, using a zero solution. According to the obtained average values of optical densities and corresponding masses of iron build a graduated schedule, postponing the abscissa shows the weight of iron, expressed in micrograms, and the y — axis the corresponding values of optical density.

6.3. Processing of the results

6.3.1. Mass fraction of iron () in percentage

,

where is the mass of iron was found in the calibration schedule, mcg;

 — the weight of the portion of the sample,

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

6.3.2. Discrepancies in the results of two parallel measurements or test results shall not exceed the values of permissible differences given in table.3.

Table 3

Sec. 6. (Added, Rev. N 1).

7. ATOMIC ABSORPTION METHOD FOR DETERMINATION OF IRON AND COPPER TO RARE EARTH METALS AND THEIR OXIDES

The method is based on measuring the atomic absorption of the element when the atomization of the sample solution into an air-acetylene flame.

(Added, Rev. N 1).

7.1. Apparatus, reagents and solutions

Atomic absorption spectrophotometer of company Perkin-Elmer M300 or similar instrument designed for operation with air / acetylene flame.

Lamp hollow cathode type of LSP for copper and iron.

Analytical scale type AV-200.

Volumetric flasks with a capacity of 25, 100, 1000 cm.

Pipettes with volume capacity of 1.5 cm.

Pipettes with no graduations 2, 5, 10, 20 cm.

Quartz chemical glasses with a capacity of 50, 100, 250 cm.

Acetylene in cylinders for technical GOST 5457−75.

Hydrochloric acid by the GOST 3118−77, H. h., diluted 1:1 and a solution with a mass fraction of 0.5%.

Nitric acid GOST 4461−77, H. h., diluted 1:1 and a solution with a mass fraction of 0.5%.

Distilled water GOST 6709−72.

Electrolytic copper powder according to GOST 4960−75.

The iron powder according to GOST 9849−86.

Standard solution of iron (spare) containing 1 mg/cmiron: a suspension of iron powder weighing 0.2 g was placed in a beaker with a capacity of 100 cm, pour 2−3 cmof distilled water and 10 cmof hydrochloric acid diluted 1:1. The dissolution is carried out at slow heating. The solution was cooled, transferred to a volumetric flask with a capacity of 200 cmand adjusted to the mark with distilled water.

Standard iron solution containing 0,0005; 0,0010; 0,0020; 0,0030 mg/cmiron: prepare a serial dilution of a backup solution of iron by hydrochloric acid solution with a mass fraction of 5%.

A standard solution of copper (spare) containing 1 mg/cmcopper: a sample of copper powder weighing 0.2 g was placed in a beaker with a capacity of 100 cm, moistened with 2−3 cmof distilled water and add 10 cmof nitric acid, diluted 1:1. The dissolution is carried out at slow heating. The solution was cooled, transferred to a volumetric flask with a capacity of 200 cmand adjusted to the mark with distilled water. Standard solutions of copper containing 0,0005; 0,0010; 0,0020; 0,0030 mg/cmof copper is prepared by successive dilution of a backup solution with a nitric acid solution with mass d

Olga is 0.5%.

7.2. Preparation of samples for analysis

Two sample of sample weight of 1 g was placed in two quartz glass with a capacity of 50 cm, pour 2−3 cmof distilled water in each of them. For the determination of iron sample dissolved in 5 cmof hydrochloric acid diluted 1:1. For the determination of copper the sample is dissolved in 5 cm.of nitric acid diluted 1:1. The dissolution is carried out under heating. The sample is evaporated to a volume of 1.5−2 cm, cooled, poured 5−7 cmof distilled water, transferred to volumetric flasks with a capacity of 25 cmand bring to mark with acid solutions with a mass fraction of 0.5% during detection of the iron — hydrochloric acid, in the determination of copper with nitric acid.

In parallel with the preparation of sample solution prepare a solution in the reference experiment

.

7.1, 7.2. (Changed edition, Rev. N 1, 2).

7.3. Analysis

The device is ready to work according to the instructions to the device. Used odnoschelevye burner with a length of 100 mm.

Wavelength: of 248.3 nm for iron, for copper 324,7 nm.

The air flow rate scale of the rotameter: «Oxydant» — 21; the flow rate of acetylene on the scale of the rotameter «Fuel» — 3 cases.

The prepared solutions of samples sprayed in air-acetylene flame and measure the atomic absorption for iron and copper. Are parallel to measurement control experience. Then measure the atomic absorption of two standard solutions larger or smaller in comparison with the atomic absorption of the sample.

To eliminate the influence of slow changes of gas pressure on the magnitude of the atomic absorption repeat the whole series of measurements in reverse order (working solutions, control and experience samples). The mass fraction of iron and copper, as the average value of the results of two parallel measurements of the same sample. If necessary, introduce an amendment in the reference experiment.

7.4. Processing of the results

7.4.1. Mass fraction of the element () in percent is calculated by the formula

,

where ,  — mass fraction of the element in the working solutions (less and more, respectively), mg/cm;

, ,  — the value of atomic absorption, respectively, for samples larger and smaller working solutions.

For each analysis item is carried out in two batches. The result of the analysis take the average of the results of two parallel measurements.

7.4.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed the values of permissible differences given in table.4.

Table 4

7.3−7.4.2. (Added, Rev. N 1).