GOST 12363-79

• gost-12363-79.pdf (469.62 KiB)
  ГОСТ 12363-79

GOST 12363−79 Steel alloyed and high alloy. Methods for the determination of selenium (with Change No. 1)

GOST 12363−79

Group B39

STATE STANDARD СОЮ3А SSR

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of selenium

Alloy and high-alloy steels.
Methods of selenium determination

AXTU 0809

Date of introduction 1981−01−01

APPROVED AND put INTO EFFECT by decision of the USSR State Committee for standards 5 Jun 1979 N 2018

Proven in 1985 by the Resolution of Gosstandart from 20.06.85 N 1808 the validity extended to 01.01.96*
_________________
* Expiration removed by Protocol No. 5−94 of the Interstate Council for standardization, Metrology and certification (I & C N 11−12, 1994). — Note the CODE.

REPLACE GOST 12363−66, in addition to General guidance

The re-release (December 1986) with amendment No. 1, approved in June 1985 (IUS 9−85).


This standard establishes titrimetric and photometric methods for the determination of selenium (in mass fractions of from 0.03 to 0.50%), extraction-photometric method for the determination of selenium (at a mass fraction of from 0.06 to 0.5%) polarographic method for the determination of selenium (at a mass fraction of from 0.05 to 0.50%) in the alloy and high-alloy steels.

1. GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 20560−81.

2. TITRIMETRIC METHOD FOR THE DETERMINATION OF SELENIUM

2.1. The essence of the method

Selenium (IV) is reduced with sulfur acid to elemental selenium precipitate which is separated and then dissolved in acid. Selenium (IV) is reduced with potassium iodide and titrate the released iodine with sodium thiosulfate.

2.2. Reagents and solutions

Hydrochloric acid by the GOST 3118−77 and diluted 1:2, 1:3, 1:10.

Nitric acid GOST 4461−77.

Sulfuric acid GOST 4204−77, diluted 1:4.

Urea according to GOST 6691−77.

The soluble starch according to GOST 10163−76, a solution of 1 g starch is mixed in 5 cmof water, poured with stirring 100 cmof hot water, bring to the boil and cooled. Prepared on the day of use.

Potassium iodide according to GOST 4232−74, a solution of 30 g of potassium iodide dissolved in 100 cmof water. Prepared before use.

Sulfurous acid, 6% solution. Prepared by saturating water with gaseous sulphurous anhydride, which is obtained by the action of sulphuric acid on metallic copper when heated.

The enrichment of water gas with sulfur dioxide control permanentresidence the titration of a solution of sulphurous acid.

To 50−70 cmof water in the conical flask with a capacity of 250 cmpour 1 cmof a saturated solution of sulphurous acid, 15 cmof sulphuric acid (1:4) and titrated with a 0.1 mol/DMsolution of potassium permanganate (3.2 g/DM) until the appearance of pink color.

The saturation is stopped when titration is used not less than 15 cmof 0.1 mol/DMpotassium permanganate solution.

Use a freshly prepared solution of sulphurous acid.

Selenium metal according to GOST 5455−74.

Selenous acid, standard solution: 1 g of metallic selenium is dissolved in 50 cmof nitric acid by heating on a water bath. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DMwas diluted to the mark with water and mix. 1 cmof the resulting solution contains 0.001 g of selenium.

Sodium thiosulfate crystal according to GOST 244−76, 0.01 mol/DMtitrated a solution of 2.48 g of sodium thiosulfate dissolved in 1 DMsvejeprokipachenna and cooled water and add 0.1 g of sodium carbonate. The solution was stored in a flask made of dark glass. Mass concentration of the solution set in 2−3 days by standard solution of selenous acid.

2−4 cmstandard solution of selenous acid was placed in a conical flask with a capacity of 250 cm, 100 cm pourheated to the boiling point of water and 25 cmof hydrochloric acid. Add 2 g of urea, the solution was stirred and after 20 minutes, cool. The solution was poured 80 cmwater, 10 cmpotassium iodide solution, mix and leave for 2−3 minutes Then pour 2 cm ofstarch solution and titrated with sodium thiosulfate with a concentration equivalent to 0.01 mol/luntil the disappearance of blue color.

The concentration of sodium thiosulfate on selenium g/cm, is calculated by the formula

where is the mass of selenium in a 1 cmstandard solution, g;

 — the volume of a standard solution of selenous acid taken for titration, cm;

 — the volume of sodium thiosulfate consumed for the titration, ml;

 — the volume of sodium thiosulfate consumed in the titration in a control experiment, cm.

(Changed edition, Rev. N 1)

.

2.3. Analysis

A sample of steel weighing 2 g were placed in a glass with a capacity of 300−400 cm, flow 15 cmof nitric and hydrochloric acid and 25 cmof water. Dissolve a portion with a moderate heat, and then evaporate the solution to dryness at low heat (120 °C).

To the dry residue poured 20 cmof hydrochloric acid (1:2) and the contents of the beaker heated in a water bath to dissolve salts. The solution is cooled, add a little filtrowanie mass, made from ash-free filter medium density («white ribbon»), pour the 140 cmof hydrochloric acid, 70 cmof a solution of sulphurous acid and thoroughly mix the solution with a glass rod. The glass is placed in a water bath with a temperature of 60−70 °C for 30−40 min and then left overnight. Elemental selenium precipitate together with the filter mass is filtered on a thick filter (the"blue ribbon") and washed 5−6 times with hydrochloric acid (1:3), 5−6 times a hot solution of hydrochloric acid (1:10) and 5−6 times with hot water. The filter with precipitate was placed in a beaker, in which was deposited elemental selenium, poured 25 cmhot hydrochloric acid and 7−10 drops of nitric acid. Heat the contents of the beaker until complete dissolution of the precipitate elemental selenium in a water bath (10−15 min), pour 100 cm, heated to the boiling point of water, add 2 g of urea, mix and leave for 20 min. Then cool the solution, pour 80 cmwater, 10 cmpotassium iodide solution, mix and leave for 2−3 min. Pour 2 cm ofstarch solution and titrated with sodium thiosulfate until the complete disappearance of the blue OCD

ASKI.

2.4. Processing of the results

2.4.1. Mass fraction of selenium in percent is calculated by the formula

where is the concentration of sodium thiosulfate on selenium, g/cm;

 — the volume of sodium thiosulfate consumed in the titration, cm;

 — the volume of sodium thiosulfate consumed in the titration in a control experiment, cm;

the weight of steel, g

.

2.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence level = 0.95 does not exceed the values specified in table. 1.

3. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF SELENIUM

3.1. The essence of the method

Selenium (IV) restore sulfate hydrazine in the presence of monochloride of iodine to form elemental selenium precipitate which is separated and then dissolved in acid. Selenium (IV) in the solution again reduced to elemental tin chloride in the presence of copper sulphate and gelatin and measure the absorption of a colloidal solution of elemental selenium.

3.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Nitric acid GOST 4461−77.

Hydrochloric acid by the GOST 3118−77.

A mixture of hydrochloric and nitric acids, freshly made: to 150 cmof hydrochloric acid pour 50 cmof nitric acid and stirred.

Iodine monochloride, solution: 0,1395 g of potassium Iodate and 0,0890 g of potassium iodide dissolved in 125 cmof water and immediately add 125 cmof hydrochloric acid.

Hydrazine sulfate according to GOST 5841−74, hot solution of 100 g/DM.

Copper sulfate according to GOST 4165−78, a solution of 20 g/DM.

Tin dichloride according to GOST 36−78, a solution of 100 g/DMin 20% hydrochloric acid.

Gelatin GOST 23058−78; a solution of 10 g/DMfreshly prepared: 1 g of gelatin was placed in a conical flask, poured 100 cmof water and leave at room temperature for 25−30 min, stirring the solution 3−4 times, then the solution was heated to 60−70 °C and kept at this temperature until complete dissolution of gelatin.

Selenium metal according to GOST 5455−74.

Selenous acid, standard solution: 0.1 g of metallic selenium was dissolved in 10 cmof hydrochloric acid with the addition of 20−25 drops of nitric acid when heated in a water bath in the conical flask with a capacity of 50 cm, closed the watch glass. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix. 1 cmof the resulting solution contains 0.1 mg

selenium.

3.3. Analysis

A sample of steel weighing 0.5 g when the mass fraction of selenium from 0.03 to 0.05%, 0.25 g when the mass fraction of selenium over 0.05 to 0.20% and 0.1 g for the mass concentration of selenium in excess of 0.20 to 0.50% is placed in a conical flask with a capacity of 50−100 cm, flow 6−7 cm, a mixture of hydrochloric and nitric acids, close the flask watch glass and dissolve a portion of steel with moderate heating. The solution was cooled, transferred to a conical flask with a capacity of 250 cm, washing the walls of 70−80 cmof water. The solution is heated on a water bath to 40−50 °C, poured into a flask of 10 cmsolution of monochloride of iodine, add a little filtrowanie mass, 15 cmof a 10% hot solution of sulfate hydrazine and stirred. The flask with the solution is kept in a water bath for one hour. The solution was then cooled to room temperature, the precipitate elemental selenium is filtered off on a medium density filter (white ribbon) with a diameter of 7 cm. Washed the flask and the filter with the sediment 3−4 times with small portions of water. The filter cake was dissolved in 5−7 cmof hot hydrochloric acid, to which is added three drops of nitric acid, collecting the filtrate in a volumetric flask with a capacity of 25 cm. The filtrate was washed with small portions of hot water until until the filtrate volume reaches 15 cm. The filtrate was cooled to room temperature, the flask is administered 2 drops of solution of sulphate of copper, 2 cmgelatin solution gradually, with stirring, 2 cmof a solution of dichloride of tin. The solution was diluted to the mark with water, mix and leave on for 15−20 minutes, measure the optical density on the spectrophotometer at a wavelength of 453 nm or photoelectrocolorimeter with a filter having a transmission region of 450−480 nm in a cuvette with a layer thickness of 1 cm as a solution of comparison, use water. The mass of selenium in grams, as amended by the control of the experience is determined by the calibration schedule.

3.3.1. Construction of calibration curve

In six conical flasks with a capacity of 100 cmare placed depending on the assumed mass fraction of selenium in the sample 0.1; 0.25 or 0.5 g of steel, similar in composition to the analyzed, but not containing selenium (see p.3.3). Five flasks consistently go 1, 2, 3, 4, 5 cmof a standard solution of selenium that corresponds to 0,0001; 0,0002; 0,0003; 0,0004; 0.0005 g of selenium. To each flask add 6−7 cmof a mixture of hydrochloric and nitric acids and then carry out the analysis as described in section 3.3. From the values of optical density of analyzed solutions is subtracted the value of the optical density of the solution in the reference experiment. The found values of optical density and corresponding values of the masses of Selena build the calibration graph.

3.2.-3.3.1. (Changed edition, Rev. N 1).

3.4. Processing of the results

3.4.1. Mass fraction of selenium in percent is calculated by the formula

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

the weight of steel,

3.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence level = 0.95 does not exceed the values specified in table. 1.

4. EXTRACTION-PHOTOMETRIC METHOD

4.1. The essence of the method

The method is based on extraction with toluene complex compounds of selenium (IV) with ortofenantrolinom and measuring the light absorption of the extract at a wavelength of 330 nm. The influence of concomitant elements can be eliminated by addition of phosphoric acid and Trilon B.

4.2. Apparatus, reagents and solutions

Spectrophotometer with accessories, pH meter-millivoltmeter.

Hydrochloric acid by the GOST 3118−77.

Nitric acid GOST 4461−77.

A mixture of hydrochloric and nitric acids: the 150 cmof hydrochloric acid pour 50 cmof nitric acid with stirring.

Sulfuric acid of high purity according to GOST 14262−78 or GOST 4204−77, a solution of 1:1 and 0.5 mol/DM.

Formic acid according to GOST 5848−73.

Orthophosphoric acid according to GOST 6552−80.

Ammonia water according to GOST 3760−79.

Orthophenylphenol, recrystallized, a freshly prepared solution with a concentration of 10 g/DM.

Toluene according to GOST 5789−78.

The salt disodium--tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, a solution with a concentration of the equivalent 0,1 mol/DM.

Selenium of high purity.

The standard solutions of selenium (IV).

Solution a (the concentration of selenium 0.0001 g/cm): 0.1 g of selenium were placed in a glass, add 10 cmof nitric acid, and dissolve in low heat, add a 10 cmdiluted 1:1 solution of sulfuric acid and evaporated to start the selection of sulfuric acid vapor.

The resulting salt is dissolved by heating in 20−30 cmof water, the solution was transferred to volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

Solution B (the concentration of selenium 0,00002 g/cm), prepared before use by dilution of solution A:200 cmsolution And transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and AC

eshivot.

4.3. Analysis

4.3.1. The weight of the portion of the sample depending on the mass fraction of selenium are given in table. 2.

Table 2

The sample is placed in a steel beaker, add 30 cmof a mixture of nitric and hydrochloric acids is 1:3, and dissolve in low heat, add 20 cmof the diluted (1:1) solution of sulfuric acid and evaporate the solution at low heat to start the selection of sulfuric acid vapor. The resulting salt is dissolved by heating to 30−40 cmof water, the solution was transferred to volumetric flask with a capacity of 100 cm, adjusted to the mark with water, mixed and filtered through a dry filter into a dry conical flask, discarding first portion of filtrate. Aliquot part of the solution was 10 cmplaced in a beaker, add 20 cmof water, 2 cmof formic acid. 5 mmphosphoric acid, 1 cmTrilon B, stirred and aqueous ammonia added to pH 1 (monitoring by pH-meter). To the obtained solution add 3 cmof a solution of ortopeediline, mix and leave for 20 min. the Solution was transferred to a separating funnel, washing the side of the Cup a minimum amount of water, add 10 cmof toluene and shaken for 2 min.

After the separation of the lower layer is drained and discarded. Extract containing a complex compound of selenium with ortofenantrolinom, filtered through a glass funnel with a cotton swab, collecting the filtrate in a volumetric flask with a capacity of 25 cm, and washed swab a small amount of toluene. The filtrate in the flask was adjusted with toluene to the mark, mix and photometered on the spectrophotometer at = 330 nm in a quartz cuvette with a layer thickness of 10 mm, using as a comparison solution

toluene.

4.3.2. Construction of calibration curve

Six glasses with a capacity of 300−400 cmconsistently poured 5,0; 10,0; 15,0; 20,0; 25,0; 30,0 cmstandard solution of selenium B, which corresponds to 0,0001; 0,0002; 0,0003; 0,0004; 0,0005; 0,0006 g selenium, add 30 cmof a mixture of hydrochloric and nitric acids 3:1, and further receives, as described in Chapter 4.3.1.

On the found values of optical density and corresponding mass of selenium build the calibration graph.

4.4. Processing of the results

4.4.1. Mass fraction of selenium in percent is calculated by the formula

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

the weight of steel,

4.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence level = 0.95 does not exceed the values specified in table. 1.

5. POLAROGRAPHIC METHOD

5.1. The essence of the method

The method is based on the detection of the polarization curves for the recovery of selenium (IV) in sulfuric acid (0.5 mol/DM) on the surface of mercury dripping electrode. From accompanying elements the selenium separates in the form of elemental recovery of hydrazine sulfate.

5.2. Apparatus, reagents and solutions

Polarograph oscilloscope-5122 or AC-PPT-1. Allowed to use data handling other brands.

The polarographic cell, made of glass, with the anode (bottom mercury) and mercury-drip cathode attached to polarography.

Hydrochloric acid by the GOST 3118−77.

Nitric acid GOST 4461−77.

A mixture of hydrochloric and nitric acids: the 150 cmof hydrochloric acid pour 50 cmof nitric acid with stirring.

Sulfuric acid of high purity according to GOST 14262−78 or GOST 4204−77, a solution of 1:1 and 0.5 mol/DM.

Potassium iodide according to GOST 4232−74.

Potassium ignominously according to GOST 4202−75.

A solution containing potassium iodide and potassium ignominously: 0.14 g of potassium iodide and 0.09 g of potassium odnomodovogo placed in a glass, pour 125 cmof water and immediately 125 cmof hydrochloric acid and stirred.

Hydrazine sulfate according to GOST 5841−74, a solution of 100 g/DM.

Selenium of high purity.

A standard solution of selenium (IV).

The solution And the mass concentration of selenium 0.0001 g/cm: 0.1 g of selenium were placed in a glass, add 10 cmof nitric acid, and dissolve in low heat, add a 10 cmdiluted (1:1) sulfuric acid solution and evaporated prior to the allocation of sulphuric acid fumes.

The resulting salt is dissolved by heating in 20−30 cmof water, the solution was transferred to volumetric flask with a capacity of 1 DM, adjusted to the mark with water and peremeci

vayut.

5.3. Analysis

The weight of the portion and dilution of the solution, depending on the mass fraction of selenium are shown in table. 3.

Table 3

The weight of steel placed in a beaker, poured 20 cmof a mixture of nitric and hydrochloric acids is 1:3, 5 cmof sulphuric acid diluted 1:1, and dissolve in low heat. Add 80−90 cmof warm water, 20 cmof a solution containing iodine and potassium ignominously, 30 cmheated sulfuric acid hydrazine, a little filtrowanie mass and stand in a warm place for 1 h. the Precipitate was filtered off on a medium density filter, washed 5−6 times with warm water. Then dissolve the residue in 20 cmhot hydrochloric acid containing 6−8 drops of nitric acid, filter and washed 3−4 times with warm water. The solution is poured 20 cmof sulphuric acid diluted 1:1, and evaporated cautiously to start the selection of the vapor of sulphuric acid, add 2−3 drops of nitric acid, wash the side of the Cup with water and again evaporated to fumes of sulfuric acid.

The contents of the beaker cool, add 20−30 cmof water, heated to dissolve the salts. The solution was transferred to volumetric flask of suitable capacity (see table. 3), made up to the mark with water and mix.

Aliquot part of the solution is 5 cmis placed in a volumetric flask with a capacity of 50 cm, go to the mark solution sulfuric acid 0.5 mol/land stirred. The solution is placed in the electrolytic cell and remove polarogram from minus 0.5 to minus 1.2 In registering a peak recovery of selenium (IV) at minus 0,85 V.

For solution comparison in three glasses placed this amount of a standard solution of selenium And selenium mass which is close to the mass of selenium in the linkage sample, poured 20 cmof the mixture of acids, 5 cmof sulphuric acid diluted 1:1. Then do as stated in

p. 5.3.

5.4. Processing of the results

5.4.1. Mass fraction of selenium in percentage find a comparison according to the formula

where  — weight of selenium in solution comparison, g;

 — the height of the peak of selenium for solution of test sample, mm;

 — arithmetic mean value of the peak height of selenium for solutions comparison, mm;

 — arithmetic mean value of the peak height of control experiments, mm;

 — the weight of the portion of the sample,

5.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence level = 0.95 does not exceed the values specified in table. 1.

Sec. 4; 5. (Added, Rev. N 1).