GOST 12351-2003

• gost-12351-2003.pdf (0.96 MiB)
  ГОСТ 12351-2003

GOST 12351−2003 (ISO 4942:1988, ISO 9647:1989) Steel alloyed and high alloy. Methods for determination of vanadium

GOST 12351−2003
(ISO 4942:1988,
ISO 9647:1989)

Group B39

INTERSTATE STANDARD

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of vanadium

Alloyed and highalloyed steels. Methods for determination of vanadium

ISS 77.080.20
AXTU 0709

Date of introduction 2005−01−01

Preface

1 DEVELOPED by the Russian Federation, the Interstate technical Committee for standardization MTK 145 «monitoring Methods of steel products"

2 INTRODUCED by Gosstandart of Russia

ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 14 dated December 30, 2003)

Was standards Bureau MGS N 4786

The adoption voted:

3 this standard is modified in relation to the international standards of ISO 4942:1988* «Steel and cast iron. The determination of vanadium. Spectrophotometric method with N-BPHA» (Annex A) and ISO 9647:1989 «Steel and cast iron. The determination of vanadium. The method of flame atomic absorption spectrometry» (Appendix B)
________________
* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link. — Note the manufacturer’s database.

4 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated March 9, 2004 N 148-St inter-state standard GOST 12351−2003 (ISO 4942:1988, ISO 9647:1989) introduced directly as a national standard of the Russian Federation from January 1, 2005

5 REPLACE GOST 12351−81

6 REISSUE. August 2006

1 Scope

This standard establishes titrimetric methods for the determination of vanadium in alloy and high-alloy steels (in mass fractions of vanadium from 0.005% to 10.0%).

Allowed the determination of vanadium by spectrophotometric (Appendix A) and by flame atomic absorption spectrometry (Appendix B).

2 Normative references

The present standard features references to the following standards:

GOST 83−79 Sodium carbonate. Specifications

GOST 199−78 Sodium acetate 3-water. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4148−78 Iron (II) sulphate 7-aqueous. Specifications

GOST 4197−74 Sodium atomistically. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4208−72 Salt oxide and ammonium double sulfate (salt Mora). Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5905−2004 metal Chrome. Specifications

GOST 6552−80 orthophosphoric Acid. Specifications

GOST 6691−77 Urea. Specifications

GOST 7172−76 Potassium preservatory

GOST 10484−78 Acid fluoride-hydrogen. Specifications

GOST 11125−84 nitric Acid of high purity. Specifications

GOST 14262−78 sulphuric Acid of high purity. Specifications

GOST 20478−75 Ammonium neccersarily. Specifications

GOST 20490−75 Potassium permanganate. Specifications

GOST 28473−90 Iron, steel, ferroalloys, chromium and manganese metal. General requirements for methods of analysis

3 General requirements

General requirements for methods of analysis GOST 28473.

4 Definition of vanadium by the method of amperometric titration (at a mass proportion of from 0.01% to 0.2%)

4.1 the essence of the method

The method is based on the oxidation of vanadium (IV) with potassium permanganate in sulfuric acid medium and the amperometric titration of vanadium (V) sulfate solution ammonium iron (II). The impact of chromium, preventing the determination of vanadium, eliminate binding of chromium (III) complex with sodium acetate with the deposition of vanadium on iron (III) hydroxide after oxidation of chromium (III) to chromate in ammoniacal medium, the Stripping of chromium chloride gromila.

4.2 Equipment, reagents and solutions

Any fitting suitable for amperometric titration of vanadium-defined metrological characteristics of accuracy.

Hydrochloric acid according to GOST 3118.

Nitric acid according to GOST and GOST 4461 11125.

Perchloric acid 57%.

Orthophosphoric acid according to GOST 6552.

Iron (II) sulfate 7-water according to GOST 4148, a freshly prepared solution of 2 g of iron sulfate (II) dissolved in water, add 5 cmof sulphuric acid and dilute the solution with water to a volume of 100 cm.

Potassium permanganate according to GOST 20490, solutions of the mass concentration of 25 g/DMand with a molar concentration equivalent to 0.05 mol/DM.

Sodium atomistically according to GOST 4197, freshly prepared solutions of the mass concentrations of 20 and 2 g/DM.

Sulfuric acid according to GOST 4204, GOST 14262 and diluted 1:4, 1:9 and 1:20.

Urea according to GOST 6691, a freshly prepared solution of the mass concentration of 100 g/DM.

Ammonium neccersarily according to GOST 20478, solution mass concentration of 200 g/DM.

Ammonia water according to GOST 3760.

Sodium acetate 3-water according to GOST 199, solution mass concentration of 500 g/DM.

Vanadium pentoxide, extra pure.

Standard solutions of vanadium.

Solution a: 1,7852 g of vanadium pentoxide dissolved in 60 cmof sulphuric acid (1:9), add 5 cmof nitric acid; the solution was boiled to remove oxides of nitrogen and evaporated to release vapors of sulfuric acid. Cool, wash the side of the Cup with water and again evaporated to release vapors of sulfuric acid. After cooling, add 100 cmof water and dissolved salts when heated. The solution was cooled and transferred to volumetric flask with a capacity of 1 DM, made up to the mark with sulphuric acid (1:9) and stirred.

1 cmstandard solution contains 0.001 g of vanadium.

Solution B: 100 cmstandard solution And placed in a volumetric flask with a capacity of 1 DM, made up to the mark with sulphuric acid (1:9) and stirred.

1 cmstandard solution B contains 0.0001 g of vanadium.

Ammonium-iron (II) sulfate (Mohr salt) according to GOST 4208, solution with molar concentration of equivalent of 0.01 mol/l: 4 g of salt Mora is dissolved in 400 cmof water, add 50 cmof sulphuric acid and cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Chrome according to GOST 5905, a solution of 1 g of chromium metal is placed in a beaker or flask with a capacity of 250−300 cm, dissolved by heating in 30 cmof hydrochloric acid and cooled. The solution was transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.01 g of chromium.

The mass concentration of salt solution Mora with molar concentration of equivalent of 0.01 mol/DMinstalls on a standard solution of vanadium: 2−5 cmstandard solution of vanadium And placed in a beaker with a capacity of 250 cm, add 50 cmof sulphuric acid (1:4), 10 cmof iron sulfate solution, dilute with water to a volume of 150 cmand cooled to a temperature not above 15 °C. To the solution was added dropwise a solution of potassium permanganate (25 g/DM) until the pink color does not disappear within 1−2 minutes, the solution was then azotistykh sodium (20 g/DM) until the disappearance of the pink color and immediately 10 cmof the urea solution.

The resulting solution after 3 min. titrated with a solution of salt Mora, setting the endpoint of a titration amperometric or potentiometric method in the presence of 10 cmof phosphoric acid or visually with the addition of 5−6 drops phenylanthranilic acid, as described in section 6.

The mass concentration of salt solution Mora , g/cmvanadium, calculated by the formula

, (1)

where is the mass of vanadium, the corresponding aliquote part of a standard solution of vanadium, taken for titration, g;

 — the volume of salt solution Mora, used for titration, sm.

Allowed determination of the mass concentration of salt solution Mora for potassium dichromate.

Ammonium-iron (II) sulfate (Mohr salt) according to GOST 4208, solution with a molar concentration equivalent of 0.002 mol/DMof 200 cmof salt solution Mora with molar concentration of equivalent of 0.01 mol/DMare placed in a volumetric flask with a capacity of 1 DM, made up to the mark with sulphuric acid (1:20) and stirred.

The mass concentration of salt solution Mora molar concentration of 0.002 mol/DMinstalls on a standard solution of vanadium. For that 5−10 cmof a standard solution of vanadium B is placed in a beaker with a capacity of 250 cm, add 50 cmof sulphuric acid (1:4), 10 cmof iron sulfate solution (II) water up to 100 cmand cooled to a temperature not above 15 °C. To the solution with constant stirring, added dropwise a solution of potassium permanganate molar concentration of 0.05 mol/DMbefore the appearance of a pink color does not disappear within 1−2 min, a solution of azotistykh sodium (2 g/DM) until the disappearance of the pink color and immediately 10 cmof the urea solution. The resulting solution after 3 min. titrated with a solution of salt Mora molar concentration of 0.002 mol/DM, when setting the endpoint of a titration amperometric method. If steel with a mass fraction of chromium of more than 3% during the analysis requires the removal of chloride promila, mass concentrations of solutions of salt Mora molar concentrations of 0.01 and 0.002 mol/DMset in the following manner: in a beaker with a capacity of 250 cmis placed the required amount of standard solution of vanadium and added to a solution of trivalent chromium in amounts corresponding to the chromium content in the analyzed samples, add 20−30 cmof hydrochloric acid and 40−50 cmof perchloric acid and carried through the entire analysis, as specified in 4.3.1.

4.3 analysis

Steel weighed 1 g when the mass fraction of vanadium, up to 0.01% to 0.1% or 0.5 g when the mass fraction of vanadium in excess of 0.1% to 0.2% is placed in a beaker with a capacity of 400 cmand dissolved one of the following ways, depending on the chemical composition of the steel.
_______________
* The text of the document matches the original. — Note the manufacturer’s database.

When the mass fraction of chromium is less than 3% and the absence of tungsten in the sample of steel is dissolved in 20−30 cmof hydrochloric acid and 10−15 cmof nitric acid when heated. Then pour 50 cmof sulphuric acid (1:4), the solution is heated to release vapors of sulfuric acid and cooled. The side of the Cup washed with water and the solution again heated to release vapors of sulfuric acid, cool, add 40−50 cmof water and dissolved salts when heated.

The solution was transferred to a beaker with a capacity of 250 cm, dilute with water to volume of 100 cm, 2−5 cm, addthe iron sulfate solution (II) and cooled.

When the mass fraction of chromium of more than 3% and the absence of tungsten in the sample was dissolved in 20−30 cmof hydrochloric acid while heating, then pour 10−15 cmof nitric acid and heated until complete dissolution of the sample.

In the presence of tungsten steel sample is dissolved in the presence of 5 cmof phosphoric acid, as indicated above, depending on the mass fraction of chromium.

When the mass fraction of chromium of less than 7% analysis continue on to 4.3.3.

For the mass concentration of chromium more than 7% of chromium is separated on 4.3.1 or 4.3.2 and continue with the analysis in 4.3.3.

4.3.1 Department of transport of chromium chloride gromila

Poured in a solution of 40−50 cmof perchloric acid and heated to oxidation of chromium. Continuing to heat the solution, periodically adding to it hydrochloric acid 3−5 drops before the termination of allocation of brown fumes of chloride gromila.

After distilling off chromie chloride solution is heated to release dense fumes of perchloric acid and cooled. The side of the Cup washed with water and then the solution is heated to release dense fumes of perchloric acid, which allow to stand 2−3 min. the Solution was cooled, poured 50 cmof sulphuric acid (1:4), dissolve the salt by heating and the solution cooled. Then add 10−15 cmof a solution of iron sulfate (II) and transfer the contents into a glass with a capacity of 250 cmby diluting with water to a volume of 100 cm, cool.

4.3.2 co-deposition of vanadium on iron hydroxide after oxidation of chromium (III) to chromate in ammonia environment

To the solution obtained using one of the methods specified in 4.3, add 40−50 cmsolution naternicola ammonium, poured ammonia until the precipitation of hydroxides of iron and 15−20 cmin excess. Heat the solution to precipitate to the boil and leave in a warm place plate to the coagulation of the precipitate.

The hot solution is filtered through a medium density filter, the filtrate discarded. The precipitate is washed on the filter 5−6 times in hot water with the addition of 3−5 cmof ammonia solution per cubic decimeter of water until until the filtrate becomes colorless.

The precipitate from the filter washed with hot water into a glass, which conducted the deposition, the filter was washed 2−3 times in portions of 10−15 cmof hot hydrochloric acid (1:1) and 2−3 times with hot water. To the resulting solution was added to 50 cmof sulphuric acid (1:4), the solution is evaporated to fumes of sulfuric acid. Cool, add water to dissolve the salt and again evaporated to fumes of sulfuric acid. The obtained Sol was cooled and dissolved in 50−70 cmof water. Add 1−2 cmof iron sulfate solution (II).

4.3.3 When the mass fraction of chromium in the steel more than 3% of the solution obtained by any of the methods mentioned above, add 10 cmof a solution of sodium acetate. The solution was cooled to 10 °C — 15 °C and kept for 1 h.

To the solution, having a temperature not above 15 °C, add dropwise a solution potassium with molar concentration of equivalent of 0.05 mol/DMbefore the appearance of a pink color and after 1 min the solution azotistykh sodium (2 g/DM) until the disappearance of the pink color and immediately 10 cmof the urea solution.

After 3 min into the solution immerse a selected pair of electrodes establish the required voltage, turn on the ammeter, magnetic stirrer and titrated with the amperometric Mohr salt solution with molar concentration equivalent of 0.002 mol/DM, adding it in small portions from microburette and noting the reading after each addition of titrant. According to the data obtained build titration curve in the coordinates: the current is the volume of titrant and find the endpoint of a titration by the intersection of straight sections of the two branches of the curve.

Mass fraction of vanadium is calculated at 7.1.

5 the Determination of vanadium by the method of coulometric titration (in mass fraction from 0.005% to 0.25%)

5.1 the essence of the method

Method coulometric titration of vanadium based on the interaction of vanadium (V) with electrochemically generated iron ions (II). The endpoint of a titration amperometric set with two polarized platinum electrodes. Influence of tungsten and chromium can be eliminated by tying them in conjunction with phosphoric acid and acetic acid sodium respectively, or separation from vanadium.

5.2 Equipment, reagents and solutions

A potentiostat operating in the mode specified current.

Setup for amperometric titrations with two polarized indicating electrodes.

Working generator tungsten electrode area of the visible surface of 1.0−2.0 cm; auxiliary platinum electrode area of 0.5−1.0 cm.

Use as a working generating electrode stekloproduktsii electrode surface area of 1.0−2.0 cm.

Indicator system: two identical platinum electrodes with an area of 1 cmwith a voltage source supplying a voltage to the electrodes of at least 100 mV.

Stopwatch.

Tungsten metal electrode to the generator (purity not less than 99%).

Alum salesonline, solution of molar concentration 0.5 mol/DM: 240 gentoomaniac alum dissolved in 500 cmof water, gently poured 100 cmof sulphuric acid and heated until complete dissolution of salts. The solution was cooled, top up with water to 1 DM, thoroughly mixed and filtered through a filter of medium density.

Ammonium-iron (II) sulfate (Mohr salt) according to GOST 4208, the solution concentration of 12 g/DM: 12 g of salt Mora is dissolved in 400−500 cmof water, carefully pour 50 cmof sulphuric acid, cool, add water to 1 DM, stirred and filtered through a dry filter of medium density.

Sulfuric acid according to GOST 4204 or GOST 14262, solution with molar concentration of the equivalent 0,1 mol/DM.

The other reagents and solutions in 4.2 and 6.2.

5.3 analysis

The weight of steel, according to table 1 is dissolved in 4.3 depending on the chemical composition of the steel.


Table 1

When the mass fraction of chromium in the steel is over 5% it is on 4.3.1 or 4.3.2.

To the solution obtained by the methods specified in 4.3, pour 1−2 cmof salt solution Mora.

For steels alloyed with chromium, to the obtained solution poured 10 cmof a solution of sodium acetate and allowed to stand for 1 h.

The glass of the analyzed solution set on the mixer include stirring, add a 10 cmgentoomaniac alum, poured dropwise a solution of potassium permanganate (25 g/DM) to steady for 1 min the pink color of the solution. After 1−2 min added dropwise a solution of azotistykh sodium (20 g/DM) until complete disappearance of the pink coloration immediately, and 1−2 g of urea.

In the glass down the generator and indicator electrodes set on the display electrodes, the polarization voltage of 50−100 mV. In another glass filled with sulfuric acid with molar concentration of the equivalent 0,1 mol/DM, lower auxiliary platinum electrode and a short circuit salt bridge filled with sulfuric acid of the same concentration.

Note the initial position of the indicator of the measuring device included in the system of the indication of the titration end point. At the same time the generator current and the stopwatch. The electrolysis was carried out until until the indicator of the measuring device begins to deviate from the original position. Turn off the generator current, simultaneously stopping the stopwatch, record the indicator current time and include the current generator and a stopwatch for 3−10 4−5 times, each time recording the readings.

Build the graph of the indicator current time and find the time corresponding to the end point of the titration, at the intersection of the straight sections of the two branches of the curve.

Mass fraction of vanadium is calculated at 7.1.

6 Determination of vanadium methods amperometric, potentiometric or visual titration (at a mass fraction of from 0.05% to 10.0%)

6.1 the essence of the method

The method is based on the oxidation of vanadium (IV) with potassium permanganate in acidic medium and titration of vanadium (V) sulfate solution ammonium iron (II). The endpoint of a titration is determined amperometric, potentiometric or visual.

6.2 Apparatus, reagents and solutions

Any installation, suitable for potentiometric or amperometric titration of vanadium-defined metrological characteristics of the accuracy of the determination of vanadium.

Ammonium neccersarily according to GOST 20478.

Potassium preservatory according to GOST 7172.

Hydrofluoric acid according to GOST 10484.

The anhydrous sodium carbonate according to GOST 83, solution mass concentration of 2 g/DM.

Acid phenylantranilic, solution mass concentration of 2 g/DM: 0.2 g phenylanthranilic acid are dissolved in 100 cmof hot sodium carbonate solution.

The other reagents and solutions in 4.2.

6.3 analysis

The weight of steel, depending on the mass fraction of vanadium (table 2), were placed in a glass with a capacity of 400 cmand dissolved one of the following ways depending on the chemical composition of the steel.


Table 2

For the mass concentration of chromium less than 3.0% and the absence of tungsten to the sample flow 50 cmof sulfuric acid solution (1:4) and heated until dissolved. To a solution temperature of 50 °C was added ammonium neccersarily approximately 3 g per 1 g of sample weight to obtain a transparent solution. The solution is slowly heated to boiling and boiled for at least 10 min to destroy the rest of naternicola ammonium flow of 5−10 cma solution of iron sulfate (II), then add water to volume of 100 cmand cooled. When the mass fraction of chromium is less than 3% and the absence of tungsten samples, insoluble in sulphuric acid, dissolved in 20 cmof hydrochloric acid and 20 cmof nitric acid. Then add 15 cmof sulphuric acid and the solution was evaporated to release vapors of sulfuric acid. If this leaves a residue of carbide, then to the hot solution add cautiously, drop by drop nitric acid and the solution evaporated to release vapors of sulfuric acid, cool, add water to dissolve the salts and the solution again evaporated to release vapors of sulfuric acid. Salts dissolve in water, add water to volume of 100 cm. In the analysis of steels containing a large amount of carbides, the insoluble residue is filtered on a filter of medium density, containing a small amount filtrowanie mass, collecting the filtrate in a beaker with a capacity of 400 cm. The filter cake was washed 5−6 times with hot water. The filter with precipitate was placed in a platinum crucible, dried and incinerated. The precipitate was calcined at 750 °C — 800 °C and cooled. The residue in the crucible is moistened with 2−3 drops of water, add 2−3 drops of sulfuric acid and 3−4 cmhydrofluoric acid. The contents of the crucible carefully evaporated to dryness and calcined at 550 °C — 600 °C. the Residue in the crucible is fused with 1−2 g of potassium peacemaking. The crucible is cooled and the alloy is leached when heated in 30−40 cmof water. The resulting solution was attached to the main filter. The cooled solution was added 5−10 cmof iron sulfate solution (II). In the analysis of steels containing more than 3% not containing chromium and tungsten, the linkage flow of 20−30 cmof hydrochloric acid solution is heated, add 10−15 cmof nitric acid and continue heating to dissolve the sample.

When the mass fraction of tungsten of more than 3% of the sample dissolve in an appropriate manner depending on the content of chromium with the addition of 10 cmof phosphoric acid in potentiometric and visual titration and 5 cmin amperometric titrations.

Allowed other ways of dissolution of batches, ensuring complete decomposition of the sample and does not require changes in the further stage of the analysis.

For the mass concentration of chromium more than 7% separate from chrome vanadium, as specified in 4.3.1 or 4.3.2.

Solution obtained by one of the above methods, transferred to a glass for titration, add water up to 150 cmand cooled to a temperature not above 15 °C.

When the mass fraction of chromium in the steel more than 3% after 2 min add 10 cmof a solution of sodium acetate and kept for 1 h.

To the solution under constant stirring added dropwise a solution of potassium permanganate (25 g/DM) until a light pink coloring, stable within 2−3 min 1−2 min added dropwise a solution of azotistykh sodium (20 g/DM) under intensive stirring the solution until complete disappearance of the pink color and immediately add 10 cmof urea. The solution was stirred and after 3 min titrated with Mora salt solution with molar concentration of equivalent of 0.01 mol/DM, setting the end point potentiometric titration (in the presence of 10 cmof phosphoric acid) or amperometric method at a particular installation.

By visual determination of the titration end point to the solution prepared for titration, add 5−6 drops of a solution phenylanthranilic acid and titrated it with a solution of salt Mora before moving cherry color of the solution yellow-green.

Mass fraction of vanadium is calculated at 7.1.

7 Processing of results

7.1 Mass fraction of vanadium , %, calculated by the formulas:

— when volume amperometric, potentiometric or visual titration

, (2)

where  — the volume of salt solution Mora, corresponding to the end point of the titration, cm;

mass concentration of salt Mora, g/cmvanadium;

the weight of steel, g;

— in coulometric titrations

, (3)

where 0,0005280;

 — Faraday number (96500 C);

 — the atomic weight of vanadium (50,95 g);

 — the number of electrons involved in the recovery of vanadium (1);

 — force generating current, A;

 — the time corresponding to the end point of titration, C;

 — the weight of the portion of the sample,

7.2 error Norms and standards for monitoring the accuracy of results of measuring the mass fraction of vanadium are given in table 3.


Table 3

Percentage

Standards of operational control of convergence, reproducibility, and accuracy have been calculated at a confidence level of 0.95.

Algorithms for real-time control of measurement uncertainty and periodicity — according to GOST 28473.

Annex a (mandatory). Steel and cast iron. The determination of vanadium. Spectrophotometric method with N-BPHA (ISO 4942:1988)

APPENDIX A
(required)

A. 1 Purpose and scope

This standard specifies the spectrophotometric method for the determination of vanadium with N-BPHA (N-benzilpenitsillinom [NSOP (HE)N]) in the steel and iron.

The method used to determine the content of vanadium in the range of mass fraction from 0.005% to 0.5%.

A. 2 Normative references

In the present application refers to the following standards:

GOST 1770−74 laboratory Glassware measuring glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 7565−81 (ISO 377−2-89) Iron, steel and alloys. Sampling method for determination of chemical composition

GOST 29169−91 (ISO 648−77) oils. Pipette with one mark

GOST 29251−91 (ISO 385−1-84) oils. Burette. Part 1. General requirements

A. 3 the essence of the method

The method is based on dissolving the sample in acids. The impact of iron eliminate the addition of phosphoric acid to aliquote part of the solution. The addition of potassium permanganate oxidize vanadium to the pentavalent state.

Selectively reduced the excess potassium permanganate with sodium nitrite in the presence of urea, is added N-BPHA and hydrochloric acid for the formation of the complex, then the complex is extracted in trichloromethane.

Spectrometric measurement of absorption is carried out at a wavelength of 535 nm.

A. 4 Reagents and solutions

During the analysis, unless otherwise specified, use reagents of the established analytical purity, distilled water or water of equivalent purity.

A. 4.1 hydrochloric Acid, 1,19 g/cm.

A. 4.2 hydrochloric Acid, 1,19 g/cm, diluted 4:1.

A. 4.3 nitric Acid, of 1.40 g/cm.

A. 4.4 the Acid chloride, of 1.67 g/cm.

A. 4.5 orthophosphoric Acid, 1.71 g/cm.

A. 4.6 orthophosphoric Acid, 1.71 g/cm, diluted 1:1.

A. 4.7 a Mixture of hydrochloric and nitric acids.

Mix three volumes of hydrochloric acid (A. 4.1) with one volume of nitric acid (A. 4.3). Prepare a fresh mixture as required.

A. 4.8 hydrogen Peroxide, a solution of 300 g/DM.

A. 4.9 Sodium nitrite solution of 3 g/DM.

A. 4.10 Urea, a solution of 250 g/DM.

A. 4.11 Sodium tripolyphosphate (NaPO), a solution of 100 g/DM.

A. 4.12 Potassium permanganate, a solution of 3 g/DM.

A. 4.13 trichlormethane (chloroform).

A. 4.14 N-BPHA, a solution of trichloromethane 2.5 g/DM.

Dissolve 0.25 g N-benzilpenitsillina [CHCON (OH)CH] in 100 cmtrichlormethane (A. 4.13). Use freshly prepared solution or the diluted solution stored in a container made of dark glass.

A. 4.15 Iron, a solution of 10 g/DM.

Weighed with an accuracy of 1 mg 5.0 g of pure iron, free from vanadium or known in the most a low content of vanadium. Placed in a beaker with capacity of 500 cm, cover it over the watch glass and add 100 cmof the mixture of acids (A. 4.7). After a stormy vapors escaping gently heated until complete dissolution of iron.

Add 100 cmof perchloric acid (A. 4.4) increase the heater temperature until, until the start of the fluctuation of the white fumes of perchloric acid in a glass. Continue the evaporation, about 3 min.

Then the contents of the beaker cool, add 100 cmof hot water and shake to dissolve the salts. Add a few drops of hydrogen peroxide (A. 4.8) heat gradually to boiling and continue to boil for about 2 min, transferred to a volumetric flask with a capacity of 500 cm, is diluted to the mark with water and mix.

A. 4.16 Standard solutions of vanadium.

A. 4.16.1 vanadium, stock solution was 1.0 g/DM: dry a few grams of ammonium metavanadate (NHVO) in a drying Cabinet at 100 °C — 105 °C (see note) not less than 1 h and cooled to room temperature in a desiccator. Weighed with an accuracy of 1 mg 2,296 g of dried product was placed in a beaker with a capacity of 600 cm, 400 cm, addhot water and gently boil until dissolved. Cool, transferred to volumetric flask with a capacity of 1000 cm, is diluted to the mark with water and mix. 1 cmof this solution contains 1 mg of vanadium.

Note — If drying temperature is over 110 °C, decomposition of ammonium metavanadate. In this regard, should maintain a specified temperature.

A. 4.16.2 vanadium, standard solution 50 mg/DM: take 5cmof the basic solution (A. 4.16.1) in a volumetric flask with a capacity of 100 cm, is diluted to the mark with water and mix. 1 cmof this solution contains 50 micrograms of vanadium.

A. 5 Instrument

Conventional laboratory equipment.

Spectrometer.

All volumetric glassware should meet GOST 29251, 29169 or GOST GOST 1770.

A. 6 Sampling

Sampling — according to GOST 7565.

A. 7 Methods of analysis

Attention. A pair of perchloric acid is explosive in the presence of ammonia, vapour of nitrous acid, or any organic materials.

A. 7.1 Linkage

Depending on the assumed mass fraction of vanadium sample is weighed with an accuracy of 1 mg.

If test portion weight is approx:

A. 7.2 Control experience

Conduct control experience in parallel with the definition for the same method, using the same quantities of all reagents as specified in A. 7.3.2 and A. 7.3.3, but replacing the test solution with a solution of iron (A. 4.15).

A. 7.3 analysis

A. 7.3.1 Preparation of test solution

Put the linkage (A. 7.1) in a beaker with a capacity of 250 cm, covered with a glass watch glass and added 20−30 cmof the mixture of acids (A. 4.7). After a tumultuous off-gassing gently heated until complete dissolution of the sample. Add 15−20 cmof perchloric acid (A. 4.4) increase the heater temperature up until white pair of perchloric acid will not fill a glass, and continued for 3 min. evaporation. Cool, add about 30 cmof hot water, shake to dissolve the salts. Add hydrogen peroxide (A. 4.8) drop by drop until the recovery of chromium, gradually heated to boiling and kept at boiling temperature for 1−2 min to decompose excess hydrogen peroxide. After cooling, the solution was filtered through a paper filter of medium density and collect the filtrate in a volumetric flask with a capacity of 100 cmby washing the filter several times with warm water. Dilute to the mark with water and mix.

A. 7.3.2 Oxidation of vanadium

Place 25,0 cmof test solution (A. 7.3.1) in a separating funnel with a capacity of 125 cm. Add 2.0 cmof phosphoric acid (A. 4.6) and 5.0 cmof water and shake the funnel to the rotational motion. Add 0.8 cmpotassium permanganate solution (A. 4.12), shake in the same way and leave for 4 minutes, Add 5.0 cmof urea solution (A. 4.10) and then added dropwise with stirring rotational movement of 1.0 cmof a solution of sodium nitrite (A. 4.9). Stand 1 min.

A. 7.3.3 Extraction

Add 25,0 cmof hydrochloric acid (A. 4.2) and 10 cmof a solution of N-BPHA in trichlormethane (A. 4.14) in separating funnel and shaken phase for 45 s. After the layers are separated, dried the organic phase, filtering it through filter paper placed in an ordinary funnel, or through adsorbent cotton (cotton), placed in the trunk of the separating funnel into the dry measuring flask with a capacity of 50 cm. The aqueous phase is saved. Add 10.0 cmtrichlormethane (A. 4.13) to the aqueous phase remaining in the separating funnel and again shaken for 30 s. allow the layers to separate and combine the organic phase with the primary extract was diluted to the mark with trichlormethane (A. 4.13), mix (see note).

Note — it is Desirable to create the same conditions for the test and calibration solutions, spending each solution one by one through all stages of analysis from oxidation of vanadium (A. 7.3.2) before the extraction (A. 7.3.3) avoiding the development of color for the group of solutions and performing each procedure without delay if not otherwise agreed.

A. 7.3.4 Spectrophotometric measurement

Carry out the spectrophotometric measurement of the test solution at a wavelength of approximately 535 nm in a cuvette with a length of optical layer 1 cm (A. 5) after conversion of absorbance to zero relatively trichlormethane (A. 4.13).

A. 7.4 Calibration graph

A. 7.4.1 Preparation of the calibration solutions

Placed at 25.0 cmalikvotnih parts of a solution of iron (A. 4.15) in a separating funnel with a capacity of 125 cm. Add appropriate volumes of standard solution of vanadium (A. 4.16.2) and water in accordance with table A. 1, the funnel is shaken with a rotary motion according to A. 7.3.2 and A. 7.3.3, but without the addition of 5 cmof water, as in A. 7.3.2.


Table A. 1

A. 7.4.2 Spectrophotometric measurement

Carry out the spectrophotometric measurements for each solution at a wavelength of about 535 nm after setting the spectrophotometer to zero absorbance with respect to the zero solution of the calibration curve.

A. 7.4.3 Construction of calibration curve

Build a calibration graph, plotting the values of absorption relative to concentration of vanadium measured in the solutions, expressed in micrograms per cubic centimeter.

A. 8 Determination of results

A. 8.1 Processing results

Mass share of vanadium , %, is calculated by the formula

(A. 1)

where is the concentration of vanadium in the colored test solution, µg/cm;

 — the concentration of vanadium in the solution of the blank experience, µg/cm;

 — volume of test solution, cm;

 — volume aliquote part of the solution, cm;

 — painted volume of the test solution, cm;

 — the mass of sample, g;

 — mass fraction of vanadium in iron used for the reference experiment and calibration, %.

A. 9 test report

The test report must contain:

— all the information about the laboratory and data analysis;

— the method used with reference to this standard;

the results form samples;

— operations not specified by this standard or any optional operations that may affect the results of the analysis.

APPENDIX B (mandatory). Steel and cast iron. The determination of vanadium. The method of flame atomic absorption spectrometry (ISO 9647:1989)

APPENDIX B
(required)

B. 1 Purpose and scope

This standard specifies the flame atomic absorption spectrometric method for the determination of vanadium in steel and iron.

The method is applicable to determine the mass fractions of vanadium from 0.005% to 1.0%, provided that the mass of tungsten in the sample does not exceed 10 mg and/or mass of titanium is not more than 5 mg.

B. 2 Normative references

In the present application refers to the following standards:

GOST 1770−74 volumetric Glassware, laboratory glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 7565−81 (ISO 377−2-89) Iron, steel and alloys. Sampling method for determination of chemical composition

GOST 29169−91 (ISO 648−77) oils. Pipette with one mark

GOST 29251−91 (ISO 385−1-84) oils. Burette. Part 1. General requirements

B. 3 the essence of the method

The method is based on dissolving the sample the sample in hydrochloric, nitric and perchloric acid, adding a solution of aluminium as a spectrochemical buffer, spraying the solution into the flame denitrated-acetylene, spectrometric measurement of the absorption values of the radiation of the lamp with a hollow cathode free atoms to the vanadium at a wavelength of 318,4 nm.

B. 4 Reagents and solutions

Unless otherwise specified, use reagents of the established analytical purity, distilled water or water of equivalent purity.

B. 4.1 Pure iron containing less than 0.0005% of vanadium.

B. 4.2 hydrochloric Acid, 1,19 g/cm.

B. 4.3 nitric Acid, of 1.40 g/cm.

B. 4.4 the Acid chloride, of 1.67 g/cm.

B. 4.5 hydrochloric Acid, 1,19 g/cm, diluted 1:50.

B. 4.6 Aluminium, a solution of 20 g/l: dissolve 90 g of 6-water aluminium chloride (АlCl·6HO) in 300 cmof water and add 5 cmof hydrochloric acid (B. 4.2), dilute with water to 500 cmand mixed.

B. 4.7 vanadium, standard solutions.

B. 4.7.1 stock solution 2.0 g/lof vanadium

B. 4.7.1.1 preparation of a standard solution of the metal vanadium: the weight of a sample of 1,000 g, is taken to the nearest 0.001 g of high purity vanadium (purity >99,9%), dissolved in 30 cmAqua Regia [mix 3 volume of hydrochloric acid (B. 4.2) with 1 volume of nitric acid (B. 4.3)]. The solution was evaporated almost to dryness and add 20 cmof hydrochloric acid (B. 4.2). The solution was cooled and transferred quantitatively into a measuring flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmof the solution contains 2.0 mg of vanadium.

B. 4.7.1.2 Preparation of a solution of ammonium metavanadate:

A few grams of ammonium metavanadate (NHVО) (purity >99,9%) is dried in a drying Cabinet at 100 °C — 105 °C (see note) not less than 1 h and cooled to room temperature in a desiccator. Weighed 2,296 g of dried product was placed in a beaker with a capacity of 600 cm, 400 cm, addhot water and dissolve over low heat. Cooled and transferred to a volumetric flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmof the solution contains 2.0 mg of vanadium.

Note — If drying temperature is over 110 °C can occur in the decomposition of ammonium metavanadate. Must withstand the specified temperature drying.

B. 4.7.2 Standard solution 0.08 g/DM

Is placed 10 cm inbasic solution (B. 4.7.1) in a volumetric flask with a capacity of 250 cm. Dilute to the mark with water and mix. Prepare standard solution immediately before use.

1 cmof this solution contains 0.08 mg of vanadium.

B. 5 Equipment

All volumetric glassware should be class A in accordance with GOST 29251, 29169 GOST, GOST 1770.

Usual laboratory apparatus and equipment specified in B. 5.1.

B. 5.1 Atomic absorption spectrometer.

Lamp with hollow cathode is vanadium; for the formation of persistent clear red flame used good denitrated and acetylene, free from water, oil, and vanadium.

Used atomic absorption spectrometer after optimization of operational mode B. 7.3.4 have a detection limit and characteristic concentration (B. 5.1.4) corresponding to the values specified by the instrument manufacturer, and the criteria of accuracy B. 5.1-B. 5.1.3.

B. 5.1.1 Minimum accuracy (B. 1, Annex C)

Calculate the standard deviation of the 10 values of absorbance of the most concentrated calibration solution. The standard deviation should not exceed 1.0% of the average absorption.

Calculate the standard deviation of the 10 values of absorption of the least concentrated calibration solution (except a zero solution). The standard deviation shall not exceed 0.5% of the average value of absorbance of the most concentrated calibration solution.

B. 5.1.2 Limit of detection (V. 2, Appendix C)

Detection limits calculated as twice the standard deviation of the 10 values of the absorption solution containing the corresponding element with the selected level of concentration giving absorbance slightly higher than the zero solution. The detection limit of vanadium in the matrix, such a finite subject solution sample the sample should be less than 0.3 mg/lof vanadium.

B. 5.1.3 linearity of calibration curve (V. 3, Appendix C)

The slope of the calibration curve for the top 20% of the concentration region (expressed as change in absorbance) should not be less than 0.7 the values of slope for the bottom 20% of the concentration region defined in the same way.

For instruments with automatic calibration using two or more standard samples is necessary before analysis to confirm through the testimony of immigrant absorption that the above requirements for the linearity of the calibration was performed.

B. 5.1.4 Characteristic concentration (B. 4, Annex b)

The characteristic concentration of vanadium in the matrix, similar to the subject of the final solution of sample samples should be less than 1.0 mg/lof vanadium.

B. 5.2 accessories

For evaluation criteria B. 5.1.1-B. 5.1.3 and for all subsequent measurements, use a tape recorder and/or digital reader.

The extension of the scale can be used as long as the observed noise does not exceed the error of the reader, and it is always recommended to use for the values of absorbance below 0.1.

If you want to use the extension scale, and the instrument has no device for determining the expansion factor of the scale, this value can be calculated by simple division of the values of absorption corresponding solution obtained with extension and without extension of the scale.

B. 6 Sampling

The sampling carried out in accordance with GOST 7565.

B. 7 analysis

Attention. A pair of perchloric acid is explosive in the presence of ammonia, vapour of nitrous acid, or any organic materials.

B. 7.1 Mounting of samples

Depending on the assumed mass fraction of vanadium of the sample weighed:

1.00 g — if mass fraction of vanadium from 0.005% to 0.2% with a precision of 0.001 g;

0.2 g — at a mass fraction of vanadium from 0.2% to 1.0% with accuracy of 0.0002 g.

B. 7.2 Control experience

In parallel with the definition for the same procedure is carried out controlling experience using the same quantities of all reagents, including pure iron (B. 4.1).

B. 7.3 Definition

B. 7.3.1 Preparation of test solution

Put the linkage (B. 7.1) in a beaker with a capacity of 250 cm. Add 10 cmof hydrochloric acid (B. 4.2) and 4 cmof nitric acid (B. 4.3), covered with a glass watch glass. After termination of foaming, add 10 cmof perchloric acid (B. 4.4) and evaporate the solution until fumes of perchloric acid. Remove watch glass and evaporate to complete the distillation vapors of perchloric acid.

Cool, add 10 cmof hydrochloric acid (B. 4.2) and 20 cmof water and gently heated to dissolve the salts. Filter the solution through a filter of medium density in a volumetric flask with a capacity of 100 cm. Washed the filter with the precipitate with warm dilute hydrochloric acid (B. 4.5), collecting the washings in the same flask. The solution was cooled, added to 10 cmof a solution of aluminium (B. 4.6), diluted to the mark with water and mix.

B. 7.3.2 Preparation of the calibration solutions

B. 7.3.2.1 At a mass concentration of vanadium less than 0.2%

Take in 7 glasses with a capacity of 250 cm(1,00±0,01) g of pure iron (B. 4.1) add 10 cmof hydrochloric acid (B. 4.2) and 4 cmof nitric acid (B. 4.3), cover the beakers watch glass. After termination of foaming is cooled solutions, then add from burette a solution of vanadium (B. 4.7.2) in accordance with table B. 1.


Table B. 1

The definition continues, as specified in B. 7.3.1, beginning with «add 10 cmof perchloric acid (B. 4.4)».

B. 7.3.2.2, With the mass fraction of vanadium from 0.2% to 1.0%

Take in 7 glasses with a capacity of 250 cmsample of pure iron (0,20±0,01) g and respectively added to 10 cmof hydrochloric acid (B. 4.2) and 4 cmof nitric acid (B. 4.3) and cover glasses watch glass. After termination of foaming is cooled, then add from burette a standard solution of vanadium (B. 4.7.2) in accordance with table B. 1. Continue the determination as described in B. 7.3.1, beginning with «add 10 cmof perchloric acid (B. 4.4)».

B. 7.3.3 setting up the atomic absorption spectrometer is given in table B. 2.


Table B. 2

Note — manufacturer’s recommendations must comply with the following security measures:

— to take into account the explosive nature of acetylene under the regulations associated with its consumption;

to protect operator’s eyes from UV radiation through the filter;

— to clear the head of the burner of soot, because poorly cleaned burner can give flash;

— ensure that the siphon was filled with water.

B. 7.3.4 optimization of the mode of operation of atomic absorption spectrometer

It is necessary to observe the manufacturer’s instructions when preparing the appliance for use. Once the lamp current, wavelength and the gas flow is adjusted and the burner is ignited, spray water until stable readings.

Set absorption to zero, zero spraying the solution (B. 7.3.2).

Choose the integration time or the setting of damping in order to obtain a strong enough signal to meet the criteria of accuracy B. 5.1.1-B. 5.1.3.

Adjust the flame to a red flame with a height of about 20 mm. Alternately atomize the calibration solutions, the most concentrated and zero by adjusting the gas flow and the burner position (horizontal, vertical, and angled) as long as the difference in absorption values between these calibration solutions will not be maximum. Check that the spectrometer have been accurately placed on the desired wavelength. Evaluate the criteria in B. 5.1.1-B. 5.1.3 and additionally fulfill the requirement of B. 5.1.4 to ensure that the device is prepared for measurement.

B. 7.3.5 Spectrometric measurements

Set the extension of the scale so that the most concentrated calibration solution was allowed deviation, which is close to full scale. Atomize the calibration solutions in ascending order, respectively, repeating the measurement as long as each of them will have an installed accuracy, thus showing that the device has reached a predetermined stability. Choose two of the calibration solution. Solution 1, having absorption, slightly lower than the test solution, and the solution 2 having the absorbance slightly higher than that of test solution.

Spray solutions first in ascending, then in descending order with controlled solution as a secondary solution, in each case measuring the absorbance relative to water.

Again spray a complete set of calibration solutions (see note). These operations cannot be run on automatic devices, which take only two of the calibration solution. In this case, the solutions 1 and 2 should not be used for primary calibration, but it is possible to perform alternately with the controlled solution. Atomize the calibration solutions in small time intervals during the measurement of test solutions.

If the results are inaccurate, you must clear the burner from contamination.

Get the absorbance of each calibration solution.

Get the value of the absorbance of the test solution and the average value of the absorption solution in the reference experiment.

According to the calibration schedule (B. 7.4) translate the value of absorbance of test solution and control solution experience in the concentration of vanadium.

Note — When using perchloric acid to observe the following precautions:

— spray all solutions for the shortest period of time;

— always spray distilled water in between spraying test solutions, solutions for control experience and/or calibration solutions. Bring to a minimum the suction of air;

— frequently clean the burner, preventing its contamination and fully clean it inside and outside;

— provide operator ear protectors and safety glasses.

B. 7.4 Construction of calibration curve

You need to build a separate calibration curve for each measurement series and each expected range of the content of vanadium.

When using pure metals and reagents to zero the solution should give the insignificant small removals. In this case, build a calibration curve, plotting the average absorbance of the calibration solutions on the coordinate axes relative to the content of vanadium in micrograms per milliliter. Compare the value of absorbance of the analyzed solution and the absorbance value of the two nearest calibration solutions on schedule.

If the zero solution has a significant absorption, it requires more technique. In this case, the concentration of vanadium in the zero solution , µg/cm, calculated by the formula

, (B. 1)

where  — concentration of vanadium, added to the first calibration solution, µg/cm;

 — the value of zero absorption of the solution;

the value of absorption of the first calibration solution.

The resulting value is added to each nominal concentration to obtain calibration curve passing through the origin. Compare the value of absorbance of the zero solution, the test solution and the two nearest calibration solutions with this schedule. Subtract the concentration of the zero solution of the concentrations of other solutions.

Build a calibration curve, plotting the values of absorbance of the calibration solutions depending on the content of vanadium, expressed in micrograms per cubic centimeter. Compare the absorption for the two closest calibration mixtures with the schedule. If the two calibration readings do not differ from the schedule more than is allowed by the criterion of accuracy, the value of the analyzed solution is also acceptable.

B. 8 Processing of results

B. 8.1 Mass share of vanadium , %, is calculated by the formula

, (B. 2)

where is the concentration of vanadium in the sample solution determined from the calibration curve (B. 7.4), µg/cm;

the concentration of vanadium in solution in the reference experiment (B. 7.2) µg/cm;

 — mass fraction of vanadium in iron used for the reference experiment, %;

 — the weight of the portion of the sample,

B. 9 test report

The test report must contain:

— all the information about the laboratory and data analysis;

— the method used with reference to this standard;

the results form samples;

— features observed during the analysis.

— operations not specified by this standard or any optional operations that may affect the results of the analysis.

ANNEX b (mandatory). Methods for the determination of instrumental criteria of the device

THE APP
(required)

B. 1 determination of the minimum precision

Spray the most concentrated calibration solution 10 times and get 10 separate readings of absorbance and calculated the average value .

Spray the least concentrated calibration solution (excluding the zero calibration solution) 10 times, get the values of absorption and calculated the average value .

Standard deviation and most and least concentrated solutions respectively obtained from the equations

; (V. 1)

. (V. 2)

The minimum precision the most and least concentrated calibration solutions are obtained from and respectively.

V. 2 Definition of the detection limit

Prepare two solutions with the same chemical composition as the sample solution, but the mass fraction of the element in one of them must be such that the known concentration gave an absorbance approximately equal to 0.01, the second solution serves as a reference experiment the absorption .

Spray solutions each in 10 times, recording each reading for 10 s and using a sufficient extension of the scale in order to make the deviation in the signal is clearly visible.

Calculate the average absorbance from the testimony and . The standard deviation is calculated by the formula

, (B. 3)

where individually measured indication of absorption;

 — the average value of .

The limit of sensitivity is determined by the formula

(V. 4)

(usually taken equal to 2).

B. 3 Criterion of linearity of the calibration curve

After building a calibration curve (figure B. 1) before you apply, you need to check its linearity. To determine the absorbance corresponding to 20% of the range of concentrations in the upper part of the graph and the absorbance corresponding to the lower 20% range of concentrations. Expect attitude . It should not be less than 0.7.

Figure B. 1

B. 4 Determination of characteristic concentration

Prepare a solution with the same chemical composition as the sample solution, but with the known contents of the element to obtain absorption , approximately equal to 0.1.

Spray the solution concentration and the solution of the blank experience and measure the absorption and without expanding the scale.

The characteristic concentration , µg/cm, calculated by the formula

. (V. 5)