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GOST 25284.7-95

GOST 17261-2008 GOST 3778-98 GOST 3640-94 GOST 25284.8-95 GOST 25284.7-95 GOST 25284.6-95 GOST 25284.5-95 GOST 25284.4-95 GOST 25284.3-95 GOST 25284.2-95 GOST 25284.1-95 GOST 25284.0-95 GOST 25140-93 GOST 23957.2-2003 GOST 23957.1-2003 GOST 23328-95 GOST 22861-93 GOST 21438-95 GOST 21437-95 GOST 19424-97 GOST 15483.10-2004 GOST 1293.0-2006 GOST 1219.1-74 GOST 1219.3-74 GOST 21877.6-76 GOST 21877.0-76 GOST 9519.1-77 GOST 15483.1-78 GOST 15483.0-78 GOST 1293.0-83 GOST 1293.3-83 GOST 26880.1-86 GOST 1219.4-74 GOST 1219.8-74 GOST 1219.2-74 GOST 860-75 GOST 21877.3-76 GOST 21877.1-76 GOST 21877.9-76 GOST 21877.4-76 GOST 21877.7-76 GOST 21877.2-76 GOST 21877.10-76 GOST 21877.8-76 GOST 22518.2-77 GOST 22518.4-77 GOST 9519.2-77 GOST 22518.1-77 GOST 1293.6-78 GOST 15483.11-78 GOST 15483.8-78 GOST 15483.3-78 GOST 15483.6-78 GOST 19251.3-79 GOST 20580.8-80 GOST 20580.2-80 GOST 20580.3-80 GOST 1293.11-83 GOST 1293.1-83 GOST 27225-87 GOST 30608-98 GOST 19251.7-93 GOST P 51014-97 GOST 17261-77 GOST 22518.3-77 GOST 9519.3-77 GOST 8857-77 GOST 15483.4-78 GOST 19251.0-79 GOST 19251.5-79 GOST 19251.2-79 GOST 20580.1-80 GOST 20580.6-80 GOST 20580.7-80 GOST 20580.4-80 GOST 1292-81 GOST 9519.0-82 GOST 1293.10-83 GOST 1293.12-83 GOST 1293.5-83 GOST 1293.2-83 GOST 30082-93 GOST 1219.6-74 GOST 1219.0-74 GOST 1219.5-74 GOST 1219.7-74 GOST 21877.5-76 GOST 21877.11-76 GOST 15483.9-78 GOST 15483.7-78 GOST 15483.2-78 GOST 1293.9-78 GOST 15483.5-78 GOST 19251.1-79 GOST 19251.6-79 GOST 19251.4-79 GOST 20580.0-80 GOST 20580.5-80 GOST 1293.7-83 GOST 1293.13-83 GOST 1293.14-83 GOST 1293.4-83 GOST 26880.2-86 GOST 26958-86 GOST 1020-97 GOST 30609-98 GOST 1293.15-90 GOST 1209-90 GOST 1293.16-93 GOST 13348-74 GOST 1320-74 GOST P 52371-2005

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:

   
The name of the state
The name of the national authority for standardization
The Republic Of Belarus
Gosstandart Of Belarus
The Republic Of Moldova
Moldovastandart
Russian Federation
Gosstandart Of Russia
Ukraine
Gosstandart Of Ukraine

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/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова.

Ascorbic acid medical, solution 20 g/lГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, freshly prepared.

Citric acid according to GOST 3652, a solution of 200 g/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, freshly prepared.

Ammonia water according to GOST 3760.

Manganese sulfate according to GOST 435, a solution of 20 g/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова.

Hydrogen peroxide according to GOST 10929.

Potassium permanganate according to GOST 20490, a solution of 10 g/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова.

Gelatin GOST 11293, a solution of 10 g/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова.

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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаand dissolved in 50 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof ethanol with the addition of 1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof sulfuric acid solution (1:1). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof sulphuric acid, the solution was cooled, diluted solution (2.5 mol/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова) of sulfuric acid, transferred to a volumetric flask with a capacity of 1 DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, top up with solution (2.5 mol/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова) of sulfuric acid up to the mark and mix.

1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, covered with watch glass, add 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof water, carefully in small portions add 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof nitric acid. After dissolution, the sample solution was boiled to remove oxides of nitrogen, diluted with water to a volume of 150 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, add 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof a solution of manganese sulphate, heated to boiling, add 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof water, and again evaporated until the appearance of white vapors. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, using water instead of solution (2.5 mol/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова) of sulfuric acid, made up to the mark solution (2.5 mol/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова) 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаand evaporated to dryness, not proKLIMA.

Table 1

     
Mass fraction of tin, %

The volume aliquote part of the solution, cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова

The weight of the portion in aliquote part of the solution, g
From 0.001 to 0.005 incl.
20
1
SV. Of 0.005 «to 0.02 «
5
0,25



The residue in the beaker cool, add 2.5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof the solution (2.5 mol/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова) of sulfuric acid, 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof water, heated to boiling and cooled. Add 2cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof a solution of ascorbic acid 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof the citric acid solution, 1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof solution of gelatin, 3 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof acetone, 1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаphenylfluorone, stirring after each addition of the reagent. The solution was transferred to a volumetric flask with a capacity of 25 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаeach are placed 5 g of zinc is added to 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof water, cover with watch glass and cautiously add small portions of 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof nitric acid. The solutions were boiled to remove oxides of nitrogen, dilute with water to 150 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова. In five of the six cups, add 0,5; 1,0; 1,5; 2,0 and 2,5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаfrom 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 ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, %, is calculated by the formula

ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, (1)


where ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова — weight of tin, was found in the calibration schedule g;


ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова — 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

     
Mass fraction of tin The absolute maximum discrepancy
  results of parallel measurements of tin
analysis results of tin
From 0.0005 to 0.001 incl.
0,0002
0,0004
SV. 0,001 «0,003 «
0,0004
0,0008
«0,003» to 0,006 «
0,0007
0,0014
«Of 0.006» to 0.01 «
0,0015
0,0036
«0,01» 0,02 «
0,0025
0,005
«0,02» 0,05 «
0,006
0,012

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/lГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаin 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, are added 1 g of sodium chloride, 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, made up to the mark with hydrochloric acid (1:10) and stirred.

1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof the solution contains 0.0001 g of tin.

Solution B: 25 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаsolution And placed in a volumetric flask with a capacity of 250 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, made up to the mark with hydrochloric acid (1:10) and stirred.

1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, add 5 g of sodium chloride, 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof a hydrochloric acid solution (1:1) and heated. In the heating process is introduced in small portions 7−10 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrogen peroxide to dissolve the sample, transfer the solution into a volumetric flask with a capacity of 50 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова.

Table 3

     
Mass fraction of tin, %

Aliquota part of the solution, seeГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова

Linkage of alloy in aliquote part of the solution, g
Starts from 0.004 to 0.02 incl.
25
0,5
SV. 0,02 «0,05 «
10
0,2



The solution in the separating funnel is neutralized dropwise with a solution of ammonia (1:1) to slightly alkaline reaction paper «Congo», add 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid solution (1:4), 25 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаcontaining 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, each is placed 2,0; 4,0; 6,0; 8,0 and 10,0 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаstandard solution B. the Solutions are neutralized with aqueous ammonia (1:1) to slightly alkaline reaction paper «Congo», pour 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, %, is calculated by the formula

ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, (2)


where ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова — weight of tin, was found in the calibration schedule g;


ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова — 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hot water, diluted to 200 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова. Cooled and the volume was adjusted to 250 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова.

Ascorbic acid medical, solution 20 g/DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова(prepared immediately before use).

Quercetin according to the normative documentation, acidified alcoholic solution: 0.05 g of quercetin was dissolved in 300 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof ethanol under moderate heating. Cool, add 25 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid. Transferred to a volumetric flask with a capacity of 1 DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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/lГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаand 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid in a beaker with a capacity of 250 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, covered with watch glass. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, made up to the mark with water and mix.

1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof the solution contains 0.0005 g of tin.

Solution B: 10 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаsolution And placed in a volumetric flask with a capacity of 1 DMГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, added 100 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid, adjusted to the mark with water and mix.

1 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаand dissolved in 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid without heating. If the dissolution process is slow, add 2 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, made up to the mark with water and mix.

6.3.2 In a separating funnel with a capacity of 125 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаis placed 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаsolution of thiourea, 5 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof ascorbic acid solution, 20 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаsolution of quercetin and mixed. Add 25 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof the sample solution and mix again.

After 10−15 minutes add 15 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof methyl isobutyl ketone and shaken for 1 min, allow to settle. After clear phase separation, the aqueous layer is drained. Add 25 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаand dissolved in 15 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid. Add a few drops of hydrogen peroxide and evaporated to a syrupy condition, to remove any traces of tin. Add 15 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid and cooled. Transfer the solution into a measuring flask with a capacity of 50 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаeach placed 2 g of zinc, and 18 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid in which zinc is dissolved without heating. In each glass add 0; 2,0; 8,0; 12,0; 16,0; 20,0 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаstandard solution B and 20.0; 18,0; 12,0; 8,0; 4,0 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения оловаof hydrochloric acid. Add a few drops of hydrogen peroxide, cooled, transferred to a volumetric flask with a capacity of 50 cmГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, 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 ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, %, is calculated by the formula

ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова, (3)


where ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова — weight of tin, was found in the calibration schedule g;


ГОСТ 25284.7-95 Сплавы цинковые. Методы определения олова — 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.