GOST 15483.6-78

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  ГОСТ 15483.6-78

GOST 15483.6−78 (ST SEV 4808−84) Tin. Methods for determination of iron (with Amendments No. 1, 2, 3)

GOST 15483.6−78
(CT CMEA 4808−84)

Group B59

INTERSTATE STANDARD

TIN

Methods of iron determination

Tin. Methods for determination of iron

AXTU 1709

Date of introduction 1980−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

DEVELOPERS

B. C. Baev, T. P. Almanova, G. M. Vlasov, C. B. Meshkova, L. V. Mishchenko, L. D. Savilov, R. D. Kresnicka

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 13.12.78 N 3300

3. The standard complies ST SEV 4808−84 in part photometric and atomic absorption methods

4. REPLACE GOST 15483.6−70

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

7. REVISED (April 1999) with Amendments No. 1, 2, 3, approved in August 1984, October 1985, June 1989 (IUS 12−84, 1−86, 10−89)


This standard specifies the photometric, atomic absorption (at a mass fraction of iron from 0.002 to 0.05%) and visual colour (when the mass fraction of iron from 0,00002 to 0.0001%) methods for determination of iron.

Standard meets CT CMEA 4808 in part photometric and atomic absorption methods.

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis and security requirements — according to GOST 15483.0.

(Changed edition, Rev. N 1).

2. PHOTOMETRIC METHOD

2.1. The essence of the method

The method is based on dissolving the sample in a mixture of hydrochloric and bromatological acid and bromine, separation of tin Stripping in the form of bromide and subsequent measurement of the optical density of the complex compound of iron with 1,10-phenanthroline at a wavelength of 510 nm.

(Changed edition, Rev. N 2).

2.2. Apparatus, reagents and solutions

Photoelectrocolorimeter or spectrophotometer.

Hydrochloric acid of high purity according to GOST 14261.

Bromatologia acid according to GOST 2062.

Bromine according to GOST 4109.

The mixture for dissolution, cooked: 45 cmof hydrochloric acid, 45 cmbromatological acid and 10 cmof bromine.

Nitric acid according to GOST 4461 and diluted 1:1.

Hydrogen peroxide according to GOST 10929.

Acetic acid according to GOST 61.

Hydroxylamine hydrochloric acid according to GOST 5456.

Sodium acetate according to GOST 199.

Orthophenanthroline (or orthophenanthroline hydrochloric acid).

Solution I: 10 g of hydroxylamine hydrochloride dissolved in a small amount of water and bring to 1 DM.

Solution II: 1.5 g orthophenanthroline dissolved in water and adjusted to 1 DM.

Solution III: 270 g sodium acetate dissolved in 500 cmof water, pour the 240 cmof acetic acid, filtered (if necessary) and adjusted with water to 1 DM.

The reaction mixture for colorimetrically: the mixture of solutions I, II, III in the ratio 1:1:3.

Iron carbonyl.

Standard solutions of iron.

Solution a: 0,1000 g of iron is placed in a beaker with a capacity of 100 cm, is dissolved in 50 cmof a solution of nitric acid and boil to remove oxides of nitrogen. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

1 cmof the solution contains 1·10g of iron.

Solution B is prepared on the day of application: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix.

1 cmof a solution contains 1·10g of iron.

(Redrafted From

M. N 1, 2).

2.3. Analysis

2.3.1. A portion of sample weighing 0.5 g was placed in a wide glass with a capacity of 250 cm, 10 cm, pour themixture to dissolve, cover with a glass watch glass and leave you without heating to dissolve the sample. Rinse watch glass 3 cmof hydrochloric acid and the solution was evaporated to dryness at a moderate heat. Pour 5 cmof the mixture to dissolve and evaporated again to dryness. Evaporation with 5 cmof the mixture to dissolve is repeated 4−6 times until the complete removal of the tin. The dry residue moistened with 0.5 cmof hydrochloric acid, poured 3 cmof nitric acid and evaporated to a volume of not more than 0.5 cm. If the remainder is painted in a brown color, add 2 cmof hydrochloric acid, a few drops of hydrogen peroxide and evaporated to dryness. If necessary, repeat this operation. The dry residue moistened with 0.5 cmof hydrochloric acid 3 cm innitric acid and evaporated to a volume of not more than 0.5 cm. The solution is diluted with water to 20 cm, transferred to a volumetric flask with a capacity of 100 cm, dilute with water to 50 cm, 25 cm pour thereaction mixture, adjusted to the mark with water and mix. The pH of the solution should be 4−4,5.

After 30 min, measure the optical density of the solution on the spectrophotometer at a wavelength of 510 nm or photoelectrocolorimeter using the filter with a light transmission region 500−520 nm and cuvettes with an optimum thickness of the layer.

Solution comparison is the reaction mixture (25 cm), diluted to the mark with water in a volumetric flask with a capacity of 100 cm.

From the readings of the optical density of the analyzed solution subtract the readings of the optical density of the solution in the reference experiment, carried out through all stages of the analysis.

Weight of iron in the solution found by the calibration schedule.

(Changed edition, Rev.

N 1, 2, 3).

2.3.2. To build a calibration curve in eight of the nine volumetric flasks with a capacity of 100 cmmeasured 1,0; 2,0; 4,0; 6,0; 8,0; 10,0; 20,0 and 30.0 cmstandard solution B, which corresponds to 0,01; 0,02; 0,04; 0,06; 0,08; 0,10; 0,20 and 0.30 mg of iron. All the bottles topped up with water to a volume of 50 cm, 25 cm pour thereaction mixture and further receives, as described in Chapter 2.3.1. Solution comparison is the solution not containing a standard solution of iron. According to the obtained values of optical density and corresponding grades of iron to build the calibration graph.

(Changed edition, Rev. N 2).

2.4. Processing of the results

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

,

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

 — the weight of the portion of the sample corresponding to the taken aliquote part of the solution,

2.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 should not exceed the values given in table.1.

Table 1

(Changed edition, Rev. N 2).

3. VISUAL COLORIMETRIC METHOD

3.1. The essence of the method

The method is based on the formation of complex compounds of iron with 2,2-dipyridil. Tin is pre-separated by Stripping from the solution in the form of tetrabromide.

3.2. Apparatus, reagents and solutions

Quartz distillation apparatus.

Cylinders for colorimetrically pritertymi with glass stoppers.

Hydrochloric acid of high purity according to GOST 14261, additionally purified by distillation.

Bromatologia acid according to GOST 2062, purified from traces of metals by distillation in a quartz distillation apparatus.

Hydrogen peroxide, OS.h. 15−3.

Bromine according to GOST 4109, further purified by distillation.

The mixture of acids to dissolve: 25cmof hydrochloric acid is mixed with 25 cmbromatological acid and poured 15 cmof bromine.

Tartaric acid, OS.h. 9−3.

Sodium chloride, OS.h. 6−4.

2,2-dipyridyl, a solution with a mass fraction of 2% in 0.01 mol/DMhydrochloric acid solution.

The calcium chloride.

Benzene according to GOST 5955, purified by distillation.

Previously benzene was allowed to stand for days with granular calcium chloride to remove moisture.

-Cresol, purified twice by distillation (until the disappearance of yellow color) in the apparatus with an air refrigerator.

Sodium sanitarily.

Benzene-kreselnaja a mixture prepared in a ratio of 1:1 (stored in a dark glass jar).

Sodium hydroxide, OS.h. 18−3 or OS.h. 23−3.

Carbonyl iron OS.h. 13−2.

Complex healing of a buffer mixture with a pH of 4−6, purified from traces of iron: to 150 cmof water was added 7.5 g of sodium chloride, 30 g of tartaric acid, 10−11 g of sodium hydroxide and 15 g of sodium semitecolo. Stirred and heated the resulting solution until complete dissolution of salts. For removal of iron is added 40 cmof solution with a mass fraction of 2% 2,2-dipyridyl and allowed to stand for 18−20 h veridicity the Extracted complex of iron 20 cmof a mixture of benzene with cresol for 2−3 min. the Extraction is repeated. The bottom layer is poured in a quartz flask with a glass stopper, add 20 cm,2,2-dipyridyl and the next day repeat the extraction, using each time in 5−7 cmof benzene-cresoline mixture until then, until the extract becomes colorless. The cleaned mixture was filtered, diluted with water to 500 cmand stored in polyethylene or quartz bulb.

The test reagent for purity is performed as follows: take away 5 cmof the mixture, add 1 cmof solution with a mass fraction of 2% 2,2-dipyridyl and allowed to stand for 1 h. Add 1 cmof benzene-cresoline mixture, shaken for 3−4 min, leave for a few minutes and check the color of the extract. In the absence of traces of iron extract turns colorless. the pH of the obtained complex restorative buffer mixture ranges from 4 to 6. Adding it to the wet residue, obtained after evaporation of the dissolved sample tin in a mixture of acids, the pH of the solution was adjusted to 3.5 (universal indicator paper). When using a complex reducing buffer mixture for the preparation of the calibration solutions pH of the mixture is previously adjusted to 3.5 by adding purified hydrochloric acid.

Standard solutions of iron.

Solution a (spare): of 0.0500 g of iron dissolved in the quartz glass of 5 cmof hydrochloric acid diluted 1:1. After complete dissolution of the sample (in low heat) carry out the oxidation of iron with hydrogen peroxide. The solution was heated for 5 min to remove excess oxidant. After cooling, transfer the contents of the Cup into a measuring flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmof the solution contains 1·10g of iron.

Solution B: 1 cmbackup solution is transferred to a volumetric flask with a capacity of 100 cm, 3−5 cm acidified byconcentrated hydrochloric acid, diluted to the mark with water and mix.

1 cmof a solution contains 1·10g of iron.

(Modified redakts

ia, Rev. N 1, 3).

3.3. Analysis

3.3.1. A portion of tin weighing 1 g is placed in a low-quartz glass with a capacity of 50 cm, covered with a watch glass, and dissolve in 7−10 cmof the mixture of acids without heating. After dissolution of the glass sample is washed with 3−5 cmof hydrochloric acid and evaporated on a moderately heated stove to obtain a wet residue (2−3 drops). Treatment 5 cmof the mixture of acids to dissolve is repeated, evaporating the solution to dryness. Evaporation with 5 cmof the mixture of acids is carried out until complete removal of the tin.

To the residue add 0.5 cmof hydrochloric acid and evaporated to dryness. Operation of evaporation repeated. The dry residue moistened with 0.2 cmof hydrochloric acid diluted 1:1 and dissolved in 4 cmbuffer mixture. The solution is heated and boiled for 3−4 min.

The hot solution was added 2 cmof a solution of 2,2-dipyridil and leave for 1 h. the resulting solution was cooled, transferred to a cylinder for colorimetrically, dilute with water to 10 cmand compare the color of the analyzed solutions with the scale of the calibration solutions.

If the solution has a weak color, add to it 1 cmbenzene-cresoline mixture and shaken for 3 min. After separation of the layers compare color extract color extract scale the calibration solutions.

(Changed edition, Rev. N 1

3).the

3.3.2. The scale of the calibration solutions were prepared concurrently with the implementation of the definition is as follows: eight quartz glasses with a capacity of 50 cmpour 4 cmbuffer mixture with a pH of 3.5 and measure 0; 0,1; 0,2; 0,3; 0,4; 0,5; 0,7 and 1.0 cmof standard solution B, which corresponds to 0; 0,0001; 0,0002; 0,0003; 0,0004; 0,0005; 0,0007 and 0.001 mg of iron.

Add 2cmof a solution of 2,2-dipyridyl, heated nearly to boiling and allowed to stand for 1 h. Further analysis are as indicated in claim 3.3.1.

(Changed edition, Rev. N 3).

3.4. Processing of the results

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

,

where is the mass of iron in the sample solution, was found when compared with the calibration solutions, g;

 — the mass of iron in solution in the reference experiment, was found when compared with the calibration solutions, mg;*
__________________
* Dimension corresponds to the original. — Note the manufacturer’s database.

 — weight of tin,

(Changed edition, Rev. N 1).

3.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 should not exceed the values given in table.2.

Table 2

4. ATOMIC ABSORPTION METHOD

4.1. The essence of the method

The method is based on dissolving the sample in a mixture of hydrofluoric and nitric acids with water and measuring the nuclear absorption of iron in the flame of acetylene-air at a wavelength of 248.3 nm.

4.2. Apparatus, reagents and solutions

Atomic absorption spectrometer with all accessories.

A radiation source for iron.

The PTFE beakers with a capacity of 50 cmor Cup platinum with a capacity of not less than 50 cm.

The polyethylene flask with a capacity of 50 cm.

Nitric acid according to GOST 4461 and a solution of 1:2.

Hydrofluoric acid according to GOST 10484.

Mix to dissolve: hydrofluoric acid, nitric acid and water are mixed in the ratio 2:3:5 respectively. The mixture was stored in a plastic container.

Tin of high purity according to GOST 860.

Iron metal, reduced hydrogen.

Standard iron solution: 0,1000 g of iron is placed in a beaker with a capacity of 100 cm, is dissolved in 25 cmof a solution of nitric acid and boil to remove oxides of nitrogen. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

1 cmof the solution contains 0.1 mg of iron

.

4.3. Analysis

4.3.1. A portion of tin weighing 1 g were placed in a glass made of PTFE, is dissolved in 10 cmof the mixture to dissolve, adding it in small portions in order to avoid violent reaction. After dissolving the contents of the beaker heated for 1−2 minutes, without boiling, and cooled. The solution was transferred to a volumetric flask with a capacity of 50 cm, adjusted to the mark with water and mix.

Measure the atomic absorption of iron in the flame of acetylene-air at a wavelength of 248.3 nm, in parallel with solutions for constructing the calibration curve and the reference experiment.

The iron concentration in the solution found by the calibration schedule.

4.3.2. To build a calibration curve of seven glasses of PTFE was placed 1.0 g of tin of high purity, dissolved in 10 cmof the mixture to dissolve, adding it in small portions in order to avoid violent reaction. After dissolving the contents of the beaker heated for 1−2 minutes, without boiling, and cooled.

The solutions were transferred to volumetric flasks with a capacity of 50 cmand six of them measured to 0,2; 0,4; 1,0; 2,0; 4,0 and 6,0 cmstandard solution of iron, which corresponds to 0,02; 0,04; 0,1; 0,2; 0,4 and 0,6 mg of iron. Solutions was adjusted to the mark with water and mix.

Measure the atomic absorption of iron, as stated in claim 4.3.1.

According to the obtained values of atomic absorption and corresponding iron concentrations to build calibration curve.

4.4. Processing of the results

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

,

where is the iron concentration in the solution was found in the calibration schedule, g/cm;

 — the concentration of iron in solution in the reference experiment, was found in the calibration schedule, g/cm;

 — the volume of the sample solution, cm;

 — weight of tin, g

.

4.4.2. Discrepancies in the results of parallel definitions should not exceed the values given in table.1.

Method is used when the differences in quality assessment.

Sec. 4. (Added, Rev. N 2).