GOST 25284.7-95

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  ГОСТ 25284.7-95

GOST 25284.7−95 Alloy zinc. Methods for determination of tin

GOST 25284.7−95

Group B59

INTERSTATE STANDARD

ZINC ALLOYS

Methods for determination of tin

Zinc alloys. Methods for determination of tin

ISS 71.040.40*
AXTU 1709

____________________
* In the index «National standards», 2008
ISS 77.120.60. — Note the manufacturer’s database.

Date of introduction 1998−01−01

Preface

1 DEVELOPED by the Donetsk State Institute of non-ferrous metals (Danism); International technical Committee MTC 107

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (EASC Protocol No. 7 of April 26, 1995)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization, Metrology and certification dated June 2, 1997 N 204 inter-state standard GOST 25284.7−95 was put into effect directly as the state standard of the Russian Federation from January 1, 1998

4 REPLACE GOST 25284.7−82

1 SCOPE

This standard applies to zinc alloys, and sets the photometric methods for determination of tin with phenylfluorone (with mass fraction of tin from 0.001 to 0.02%) and quercetin (with mass fraction of tin from 0.0005 to 0.05%) in the samples of these alloys.

2 NORMATIVE REFERENCES

The present standard features references to the following standards:

GOST 435−77 Manganese (II) sulfate 5-water. Specifications

GOST 849−70* Nickel primary. Specifications
________________
* On the territory of the Russian Federation GOST 849−97. Here and further. — Note the manufacturer’s database.

GOST 860−75 Tin. Specifications

GOST 2603−79 Acetone. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3640−94 Zinc. Specifications

GOST 3652−69 citric Acid monohydrate and anhydrous. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4166−76 Sodium sulfate. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4233−77 Sodium chloride. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 6006−78 Butanol. Specifications

GOST 6344−73 Thiourea. Specifications

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11293−89 Gelatin food. Specifications

GOST 18300−87 ethyl rectified technical. Specifications

GOST 20490−75 Potassium permanganate. Specifications

GOST 25284.0−95 Alloy zinc. General requirements for methods of analysis

3 GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 25284.0.

4 PHOTOMETRIC METHOD WITH PHENYLFLUORONE (WITH MASS FRACTION OF TIN FROM 0.001 TO 0.02%)

4.1 the essence of the method

The method is based on dissolving the sample in nitric acid, the deposition of tin hydroxide of manganese (IV), the formation of colored complex compounds of tin with phenylfluorone and measuring the optical density of the solution at a wavelength of 510 nm.

4.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Nitric acid according to GOST 4461, diluted 1:200.

Sulfuric acid according to GOST 4204, diluted 1:1, 1:4, and the solution of 2.5 mol/DM.

Ascorbic acid medical, solution 20 g/l, freshly prepared.

Citric acid according to GOST 3652, a solution of 200 g/DM, freshly prepared.

Ammonia water according to GOST 3760.

Manganese sulfate according to GOST 435, a solution of 20 g/DM.

Hydrogen peroxide according to GOST 10929.

Potassium permanganate according to GOST 20490, a solution of 10 g/DM.

Gelatin GOST 11293, a solution of 10 g/DM.

Acetone according to GOST 2603.

Ethanol technical rectified according to GOST 18300.

Phenylfluorone in the normative documentation, solution: 0.1 g phenylfluorone placed in a beaker with a capacity of 100 cmand dissolved in 50 cmof ethanol with the addition of 1 cmof sulfuric acid solution (1:1). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with ethanol and mix. The solution was stored in a dark place.

Zinc metal according to GOST 3640 with a mass fraction of tin is less than 0.0001%.

Tin metal according to GOST 860.

A standard solution of tin: 0.1 g of tin are dissolved in 10 cmof sulphuric acid, the solution was cooled, diluted solution (2.5 mol/DM) of sulfuric acid, transferred to a volumetric flask with a capacity of 1 DM, top up with solution (2.5 mol/DM) of sulfuric acid up to the mark and mix.

1 cmof the solution contains 0,0001

g tin.

4.3 analysis

4.3.1 the sample of alloy weighing 5 g were placed in a glass with a capacity of 600 cm, covered with watch glass, add 20 cmof water, carefully in small portions add 20 cmof nitric acid. After dissolution, the sample solution was boiled to remove oxides of nitrogen, diluted with water to a volume of 150 cm, neutralized with ammonia before the advent of the stable precipitate, which is then dissolved by adding 1−2 drops of nitric acid. The solution is diluted with water to 200 cm, add 5 cmof a solution of manganese sulphate, heated to boiling, add 5 cmof potassium permanganate solution, boil for 3−5 min and leave for 1 h. the Solution and the precipitate was filtered through a filter medium density («white ribbon»), the filter with the sediment was washed 5−7 times with hot solution of nitric acid. The precipitate is washed with a deployed filter in the glass in which was conducted the deposition, and washed with 10 cmof hot sulfuric acid solution (1:4) with added 5−7 drops of hydrogen peroxide and then several times with hot water. The solution was evaporated until the appearance of white fumes of sulfur oxide (IV), cooled and the walls of the glass should be rinsed with 3−5 cmof water, and again evaporated until the appearance of white vapors. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, using water instead of solution (2.5 mol/DM) of sulfuric acid, made up to the mark solution (2.5 mol/DM) of sulfuric acid and stirred. Aliquot part of the solution in accordance with table 1 were placed in a glass with a capacity of 100 cmand evaporated to dryness, not proKLIMA.

Table 1

The residue in the beaker cool, add 2.5 cmof the solution (2.5 mol/DM) of sulfuric acid, 5 cmof water, heated to boiling and cooled. Add 2cmof a solution of ascorbic acid 5 cmof the citric acid solution, 1 cmof solution of gelatin, 3 cmof acetone, 1 cmphenylfluorone, stirring after each addition of the reagent. The solution was transferred to a volumetric flask with a capacity of 25 cm, top up to the mark with water and paramashiva

yut.

4.3.2 For the construction of calibration curve of six tumblers with a capacity of 600 cmeach are placed 5 g of zinc is added to 20 cmof water, cover with watch glass and cautiously add small portions of 20 cmof nitric acid. The solutions were boiled to remove oxides of nitrogen, dilute with water to 150 cm. In five of the six cups, add 0,5; 1,0; 1,5; 2,0 and 2,5 cmof a standard solution of tin. The solutions in all beakers neutralized with ammonia before the advent of the stable precipitate, which is dissolved by adding 1−2 drops of nitric acid. Then act in accordance with 4.3.1, selecting aliquot part at 20 cmfrom each solution.

After 30 min measure the optical density of the sample solution and solutions for constructing the calibration curve. Solution comparison is the solution not containing the tin (solution in the reference experiment).

According to the obtained values of optical densities and their corresponding masses tin build a calibration curve.

4.4 Processing of results

4.4.1 Mass fraction of tin , %, is calculated by the formula

, (1)

where  — weight of tin, was found in the calibration schedule g;

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

4.4.2 discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 2.

Table 2

Percentage

5 PHOTOMETRIC METHOD WITH QUERCETIN (AT A MASS FRACTION OF TIN FROM OF 0.004 TO 0.05%)

5.1 the essence of the method

The method is based on measuring the optical density of the solution complex compounds of tin with quercetin, extracted with butanol from hydrochloric acid solution.

5.2 the Instrument, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Hydrochloric acid according to GOST 3118, diluted 1:1, 1:4 and 1:10.

Hydrogen peroxide according to GOST 10929.

Ammonia water according to GOST 3760, diluted 1:1.

Sodium chloride according to GOST 4233.

Sodium sulphate anhydrous according to GOST 4166.

Butanol according to GOST 6006.

Quercetin to the standard documentation, a solution of 0.4 g/lin butanol.

Tin metal stamps O1 according to GOST 860.

Standard solutions of tin

Solution a: 0.1 g of tin are placed in a conical flask with a capacity of 100 cm, are added 1 g of sodium chloride, 20 cmof hydrochloric acid and heated. During heating, added dropwise hydrogen peroxide to completely dissolve the tin. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with hydrochloric acid (1:10) and stirred.

1 cmof the solution contains 0.0001 g of tin.

Solution B: 25 cmsolution And placed in a volumetric flask with a capacity of 250 cm, made up to the mark with hydrochloric acid (1:10) and stirred.

1 cmof solution B contains 0,00001 g tin.

Solution B is prepared on the day of application

I.

5.3 analysis

5.3.1 a sample of alloy weighing 1 g is placed in a beaker with a capacity of 250 cm, add 5 g of sodium chloride, 20 cmof a hydrochloric acid solution (1:1) and heated. In the heating process is introduced in small portions 7−10 cmof hydrogen peroxide to dissolve the sample, transfer the solution into a volumetric flask with a capacity of 50 cm, adjusted to the mark with water and mix.

Aliquot part of the solution in accordance with table 3 was placed in a separating funnel with a capacity of 150 cm.

Table 3

The solution in the separating funnel is neutralized dropwise with a solution of ammonia (1:1) to slightly alkaline reaction paper «Congo», add 5 cmof hydrochloric acid solution (1:4), 25 cmof a solution of quercetin and vigorously shaken for 5 min.

After phase separation, the lower aqueous layer discarded, avoiding the remainder of the aqueous phase, and the organic layer is poured into a dry beaker with a capacity of 50 cmcontaining 0.2−0.5 g of anhydrous sodium sulfate.

5.3.2 To construct the calibration curve five separatory funnels with a capacity of 150 cm, each is placed 2,0; 4,0; 6,0; 8,0 and 10,0 cmstandard solution B. the Solutions are neutralized with aqueous ammonia (1:1) to slightly alkaline reaction paper «Congo», pour 5 cmof hydrochloric acid solution (1:4) and further receives, as described in 5.3.1.

After 5 min measure the optical density of the sample solution and solutions for constructing the calibration curve at a wavelength of 440 nm.

Solution comparison is the solution of quercetin in butanol.

According to the obtained results build a calibration curve in the coordinates: the optical density is the mass of tin,

5.4 processing of the results

5.4.1 Mass fraction of tin , %, is calculated by the formula

, (2)

where  — weight of tin, was found in the calibration schedule g;

 — the weight of the portion of tin in aliquote part of the solution,

5.4.2 Discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 2.

6 PHOTOMETRIC METHOD WITH QUERCETIN (AT A MASS FRACTION OF TIN FROM 0.0005 TO 0.005%)

6.1 the essence of the method

The method is based on measuring the optical density of the solution complex compounds of tin with quercetin, extracted with methyl isobutyl ketone.

6.2 Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Zinc metal according to GOST 3640.

Hydrochloric acid according to GOST 3118, diluted 1:9.

Hydrogen peroxide according to GOST 10929, free from stabilizers containing tin.

Thiourea according to GOST 6344, solution: 12.5 g of thiourea are dissolved in 100 cmof hot water, diluted to 200 cm. Cooled and the volume was adjusted to 250 cm.

Ascorbic acid medical, solution 20 g/DM(prepared immediately before use).

Quercetin according to the normative documentation, acidified alcoholic solution: 0.05 g of quercetin was dissolved in 300 cmof ethanol under moderate heating. Cool, add 25 cmof hydrochloric acid. Transferred to a volumetric flask with a capacity of 1 DM, using water instead of ethanol, made up to the mark with ethanol and mix. If a precipitate, it is filtered off. Quercetin considered suitable for use if the optical density of the solution in the reference experiment is less than 0.1.

Methyl isobutyl ketone in the normative documentation.

Sulfuric acid according to GOST 4204, diluted 1:19.

Metal Nickel GOST 849.

A solution of Nickel, 0.5 g/l, hydrochloric acid: 0.5 g of Nickel dissolved in the minimum quantity of hydrochloric acid, transferred to a volumetric flask with a capacity of 1 DMand dilute to the mark with water.

Tin GOST 860.

Standard solutions of tin

Solution a: 0.5 g of tin are dissolved with moderate heating in 100 cmof hydrochloric acid in a beaker with a capacity of 250 cm, covered with 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 solution contains 0.0005 g of tin.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 1 DM, added 100 cmof hydrochloric acid, adjusted to the mark with water and mix.

1 cmof solution B contains 0,000005 g tin.

Ethanol technical rectified by

GOST 18300.

6.3 analysis

6.3.1 a sample of alloy weighing 2 g were placed in a glass with a capacity of 100 cmand dissolved in 20 cmof hydrochloric acid without heating. If the dissolution process is slow, add 2 cmof hydrochloric acid solution of Nickel, which activates the process of dissolution.

Add a few drops of hydrogen peroxide and cooling the solution. The solution was transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

6.3.2 In a separating funnel with a capacity of 125 cmis placed 20 cmsolution of thiourea, 5 cmof ascorbic acid solution, 20 cmsolution of quercetin and mixed. Add 25 cmof the sample solution and mix again.

After 10−15 minutes add 15 cmof methyl isobutyl ketone and shaken for 1 min, allow to settle. After clear phase separation, the aqueous layer is drained. Add 25 cmof sulfuric acid solution and shaken for 30 s. allow to settle for 5 min. After a clear phase separation, the aqueous layer is drained. In a cuvette with a working length of 1 cm pour of the organic layer, filtering it through a dry filter «red ribbon» to remove the drops that fall from the aqueous layer, and the first portions of the filtrate discarded.

It is recommended to avoid direct sunlight on the organic layer

.

6.3.3 To prepare the solution in the reference experiment the weight of zinc weight of 2 g were placed in a glass with a capacity of 100 cmand dissolved in 15 cmof hydrochloric acid. Add a few drops of hydrogen peroxide and evaporated to a syrupy condition, to remove any traces of tin. Add 15 cmof hydrochloric acid and cooled. Transfer the solution into a measuring flask with a capacity of 50 cm, adjusted to the mark with water and mix.

Then do as stated in 6.3.2.

6.3.4 To construct the calibration curve of six tumblers with a capacity of 100 cmeach placed 2 g of zinc, and 18 cmof hydrochloric acid in which zinc is dissolved without heating. In each glass add 0; 2,0; 8,0; 12,0; 16,0; 20,0 cmstandard solution B and 20.0; 18,0; 12,0; 8,0; 4,0 cmof hydrochloric acid. Add a few drops of hydrogen peroxide, cooled, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix. Then do as stated in 6.3.2.

6.3.5 Measure the optical density of the sample solution and solutions for constructing the calibration curve at a wavelength of 440 nm. Solution comparison for the sample solution is a solution of the reference experiment, for solutions in the construction of calibration curve — a solution according to 6.3.4, which does not contain tin.

According to the obtained values of optical density and corresponding contents of the tin to build the calibration graph.

The tin content in the sample determined by the calibration schedule.

6.4 Processing of results

6.4.1 Mass fraction of tin , %, is calculated by the formula

, (3)

where  — weight of tin, was found in the calibration schedule g;

 — the weight of the portion of the sample in aliquote part of the solution,

6.4.2 the discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 2.