GOST 28353.3-89

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  ГОСТ 28353.3-89

GOST 28353.3−89 Silver. Method of atomic-absorption analysis

GOST 28353.3−89

Group B59

INTERSTATE STANDARD

SILVER

Method of atomic-absorption analysis

Silver. Method of atomic-absorption analysis

ISS 39.060
77.120.99
AXTU 1709

Date of introduction 1991−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED the Main Directorate of precious metals and diamonds at the Council of Ministers of the USSR

DEVELOPERS

V. D. Small, PhD. Fiz.-Mat. Sciences (chair); T. D. Gornostaeva, PhD. chem. Sciences; G. E. Jerkovic, PhD. Fiz.-Mat. Sciences; M. V. Usol’tseva, T. P. Gray, L. V. Potanina

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 29.11.89 N 3523

3. REPLACE GOST 13638.2−79

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 5−94 of the Interstate Council for standardization, Metrology and certification (ICS 11−12−94)

6. REPRINTING. December 2005


This standard establishes the atomic absorption method for determination of impurities: gold, copper, iron, platinum, palladium, rhodium, bismuth, lead, antimony, zinc, cobalt, Nickel, arsenic, tellurium and manganese in silver with a mass fraction of silver of at least 99.9%.

The standard does not apply to silver of high purity.

The method is based on the evaporation and atomization of the sample solution into the flame of a gas burner or heated graphite furnace and measurement of the atomic absorption resonance lines of the determined elements. The relationship of size of absorption of the mass concentration of the element in the solution set with the help of calibration curve.

The method allows to determine the mass fraction of impurities in the intervals given in table.1.

Table 1

The error analysis results for the defined values of mass fractions of impurities with confidence probability of 0.95 is given in table.2.

Table 2

1. GENERAL REQUIREMENTS

General requirements for method of analysis and safety requirements according to GOST 28353.0.

2. APPARATUS, MATERIALS AND REAGENTS

Spectrophotometer, atomic absorption, allowing to work with flames of propane-butane-air acetylene-air, and the heated graphite furnace.

Lamp with full spectral* cathode for the determination of gold, copper, iron, platinum, palladium, rhodium, bismuth, lead, antimony, zinc, cobalt, Nickel, arsenic, tellurium and manganese.
________________
* The text matches the original. — Note the manufacturer’s database.

Analytical scales of the 2nd class.

Electric stove with a closed spiral.

A muffle furnace with thermostatic control to the temperature of 900 °C.

Propane-butane in cylinders for technical GOST 20448.

Acetylene, dissolved and gaseous technical GOST 5457.

Argon gas according to GOST 10157.

Standard samples of composition silver.

The agate mortar.

Pipettes with a capacity of 1, 5, 10 cm,with divisions according to GOST 29169, 29227 GOST — GOST 29230.

The piston pipette with a capacity of 0.01, 0.02 and 0.05 cm.

Volumetric flasks with a capacity of 25, 50, 100, 1000 cmaccording to GOST 1770.

Glasses glass with a capacity of 100, 200, 250, 300 cmaccording to GOST 25336.

Cylinder measuring capacity 10 cmand beakers capacity 50, 100, 250, 1000 cmaccording to GOST 1770.

Glass conical flasks with a capacity of 50 cmaccording to GOST 25336.

The corundum crucibles.

Obestochennye the filter paper of «blue ribbon» «white ribbon» on the other 6−09−1678.

Hydrochloric acid of high purity according to GOST 14261 and diluted 1:1, 1:5, 1:20, 1:100.

Nitric acid of high purity according to GOST 11125 and diluted 1:1.

Sulfuric acid of high purity according to GOST 14262 and diluted 1:9.

Tartaric acid according to GOST 5817, a solution of 10 g/DM.

Cadmium sulfate according to GOST 4456.

Buffer solution of cadmium sulfate containing 5 mg/cmof cadmium; a portion of sulphate of cadmium with a mass of 11.4 g was placed in a volumetric flask with a capacity of 1000 cm, 500 cm, addwater, mix to dissolve the salt, bring to the mark with water and mix.

Of niobium pentoxide according to GOST 23620.

Aqueous slurry of niobium pentoxide mass ratio of 1:5: a sample of niobium pentoxide by mass of 4.0 g was placed in a conical flask with a capacity of 50 cm, add 20 cmof water and stirred to form a suspension.

Nickel nitrate according to GOST 4055.

A solution of Nickel nitrate (matrix modifier) containing 1 mg/cmof Nickel: a portion of nitrate of Nickel with a mass of 4.94 g is placed in a volumetric flask with a capacity of 100 cm, 50 cm pouredwater, stirring to dissolve the salt, bring to the mark with water and mix again.

Barium peroxide is a high purity on the other 7−09−03−462.

Silver of high purity on the other 48−1-10.

Gold GOST 6835.

Carbonyl iron, radio GOST 13610.

Copper according to the GOST 859.

Bismuth GOST 10928.

Lead of high purity according to GOST 22861.

Zinc GOST 3640*.
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* On the territory of the Russian Federation GOST 3640−94. — Note the manufacturer’s database.

Antimony GOST 1089.

Tellurium GOST 17614.

Nickel GOST 849.

Cobalt GOST 123.

Palladium powder according to GOST 14836*.
______________
* On the territory of the Russian Federation GOST 31291−2005. — Note the manufacturer’s database.

Platinum powder according to GOST 14837*.
______________
* On the territory of the Russian Federation GOST 31290−2005. — Note the manufacturer’s database.

Arsenic metal, high purity for NTD.

Manganese metal according to GOST 6008.

Rhodium powder according to GOST 12342 or rhodium trichloride cetarehwodie on the other 6−09−2024.

Solutions containing 2 mg/cmof bismuth, iron, copper and Nickel: a portion of each of these metals with a mass of 200 mg was dissolved in 10 cmof nitric acid (1:1) under heating. The solution is evaporated to a volume of 2−3 cm, add 20 cmof a hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with the same acid solution and stirred.

A solution containing 2 mg/cmlead: charge lead with a mass of 200 mg was dissolved in 10 cmof nitric acid (1:1) under heating. The solution was transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix.

Solutions containing 2 mg/cmof gold, platinum, antimony, arsenic and tellurium: a portion of each of these metals with a mass of 200 mg was dissolved in 20 cmof a mixture of hydrochloric and nitric acids (3:1) under heating. The solution is evaporated to a volume of 2−3 cm, add 20 cmof a hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with the same acid solution and stirred.

Solutions containing 2 mg/cmof cobalt, manganese and zinc: the weight of each of these metals with a mass of 200 mg was dissolved in 10 cmof hydrochloric acid (1:1) under heating. The solutions were transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:5) and stirred.

A solution containing 2 mg/cmof palladium: palladium sample mass of 200 mg dissolved in 20 cmof nitric acid by heating, the solution is evaporated to a volume of 3−5 cm, flow 20 cmof a hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with the same acid solution and stirred.

A solution containing 2 mg/cmof rhodium, prepare one of the shows

denna ways:

1) a portion of rhodium (in powder) mass of 200 mg was mixed thoroughly with 5-fold quantity of peroxide of barium, fray in an agate mortar, transferred to a corundum crucible and sintered in air for 2−3 hours at a temperature of 800−900 °C (the crucible is put in a cold muffle). Sintered is cooled, transferred to a beaker with a capacity of 200 cm, moistened with water and dissolved in a solution of hydrochloric acid (1:1) until complete dissolution. If, after the dissolution of SPECA in hydrochloric acid is a residue, sintering and dissolution repeat. The resulting solution is diluted with water to a volume of 50 cmand precipitated barium sulfate by adding sulfuric acid solution (1:9) portions with constant stirring. The solution is heated to a temperature of 60−70 °C. after 2−3 hours check the completeness of the precipitation of the barium sulfate and filter it through filter «blue ribbon», or double filter «white ribbon» in a volumetric flask with a capacity of 100 cm. The filter cake was washed 4−5 times with hot hydrochloric acid (1:5), and then 5−6 times with hot water. The solution was adjusted to the mark with hydrochloric acid (1:5) and stirred.

2) the Suspension of rhodium trichloride ground 546,7 mg dissolved in 20 cmof a hydrochloric acid solution (1:1) at weak heating, the solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:5) and stirred.

Solution a: in a volumetric flask with a capacity of 100 cmis placed 5 cm insolutions of gold, iron, copper, Nickel, lead, bismuth, antimony, cobalt, zinc, platinum, palladium, rhodium, arsenic, tellurium and manganese was adjusted to the mark with hydrochloric acid (1:5) and stirred.

1 cmof the solution contains 100 µg of each of the identified elements.

Solution B: in a volumetric flask with a capacity of 100 cmis placed 10 cmsolution A, was adjusted to the mark with hydrochloric acid (1:5) and stirred.

1 cmof the solution contains 10 µg each of the identified elements.

3. PREPARATION FOR ASSAY

3.1. Preparation of the graphite tube atomizer

Processing of the graphite tubes of niobium pentoxide is carried out as follows: a graphite tube immersed in a water slurry of niobium pentoxide and allowed to stand for 2−3 hours, then the tube is dried in a graphite furnace for 60 s at 100 °C, anneal for 30 s at 1000 °C and for 10 s at a temperature of 2650 °C in stop mode, the flow of inert gas («gas-stop»). The temperature treatment was repeated at least two times.

3.2. Preparation of samples for analysis

3.2.1. To perform the analysis selected two hanging silver weight of 0.2−2.5 g (table.3), each of which is placed in a beaker with a capacity of 200−250 cmand clean the surface of silver GOST 28353.0.

Table 3

The sample was dissolved with mild heating in 10 cmof nitric acid (1:1). After complete dissolution of silver was added 5 cmof hydrochloric acid and dissolved gold and rhodium under low heat for 3−5 min the Solution is diluted with hot water to a volume of 150−200 cmand immediately filtered in a glass with a capacity of 300 cmthrough filter «blue ribbon», washed 4−5 times with hot hydrochloric acid solution (1:100) and 2−3 times with hot water, without transferring the precipitate of silver chloride on the filter. The precipitate is washed by decantation 5−6 times with hot hydrochloric acid solution (1:100). The resulting solution (filtrate 1) is evaporated to a volume of 2−3 cm.

3.2.2. A filter through which the filtration was carried out, placed in a glass of precipitate of silver chloride, add 10 cmsulphuric and nitric acids. The sample is incubated at room temperature until the cessation of the violent reaction is then heated to release dense fumes of sulphuric anhydride. The glass moved to the front of the plate, gently on the side of a glass and add 4−5 drops of nitric acid and again heat until dense fumes of sulphuric anhydride. The operation of addition of nitric acid is repeated until complete dissolution of silver chloride. The solution is evaporated to wet salts, cool, add 10 cmof nitric acid, 100−150 cmof hot water and heated to dissolve the salts. Then to the solution add 3 cmof hydrochloric acid and immediately filtered in a glass of evaporated filtrate 1 through filter «blue ribbon», previously prepared as specified in clause 3.2.1. The precipitate is washed by decantation 6−7 times with hot hydrochloric acid solution (1:100), and the filtrate is evaporated to a volume of 2−3 cm.

3.2.3. To the evaporated solution was added 3 cmof hydrochloric acid, the solution transferred to a volumetric flask with a capacity of 25−50 cm, adjusted to the mark with water and mix. If the mass fraction of detectable elements less than 0.004%, with their number not exceeding five, dilution of the solution may be performed to a volume of 10 cmin a graduated cylinder with a capacity of 10 cm.

The resulting solution was supplied for analysis.

At the same time through all stages of sample preparation to the analysis carried out two test experience on the purity of the reagents.

3.2.4. Determination of gold, platinum, tellurium, arsenic, zinc, copper, Nickel, cobalt and iron may be carried out without perioadele of silver chloride (p.3.2.1) from the filtrate 1 after dilution of the solution, as stated in claim 3.2.3.

3.3. Preparation of solutions comparison

3.3.1. For the determination of gold, copper, iron, platinum, palladium, rhodium, bismuth, lead, antimony, zinc, cobalt, Nickel, tellurium and manganese in the atomization of the sample in the flame use solutions comparison, prepared from solutions A and B.

Solutions comparison with the mass concentration of the determined elements 0,2; 0,5; 1,0; 2,0 and 5,0 mg/cmin volumetric flasks with a capacity of 50 cmis taken aliquote part of the solution A or B (tab.4), adjusted to the mark with hydrochloric acid (1:5) and stirred.

Table 4

3.3.2. For the determination of antimony, bismuth, arsenic, platinum and tellurium in the atomization of samples in a graphite furnace using the solutions of the comparison carried out through all stages of sample preparation to the analysis.

Solutions with the mass concentration of the determined elements 0,2; 0,4; 0,6 and 1,0 mkg/cm: select four sample of silver of high purity with a mass of 0.5 g, each of which is placed in a beaker with a capacity of 250 cm, clean the surface of silver GOST 28353.0 and silver dissolve in low heat and 10 cmof nitric acid (1:1). In glasses introduce respectively 1,0; 2,0; 3,0 and 5,0 cmof solution B. the Solutions were diluted with hot water to a volume of 150 cm, add 2 cmof hydrochloric acid and then the solution preparation is carried out according to PP.3.2.1, 3.2.2 and 3.2.3. When diluted solutions according to claim 3.2.3 use volumetric flasks with a capacity of 50 cm.

Solutions comparison with the mass concentration of the determined elements 0,1; 0,2; 0,3 and 0,5 µg/cmin volumetric flasks with a capacity of 25 cmis placed 5 cmabove-obtained solutions was added 5 cmof a solution of tartaric acid in the determination of antimony, or 5 cmof hydrochloric acid solution (1:20) in the determination of bismuth, arsenic, platinum, tellurium, and mix.

4. ANALYSIS

4.1. Analysis with atomization of the sample in the flame

Atomic absorption spectrophotometer are ready and include according to the instruction manual of the device. Measure the atomic absorption of the elements is carried out by analytical spectral lines with wavelengths given in table.5.

Table 5

Methods of preparation of samples for analysis and the flame that is used to define the various elements are given in table.6.

Table 6

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* In a flask with a capacity of 25 cmtaken 5 cmof the analyzed solution samples, or solution comparison, add a 5 cmbuffer solution of cadmium sulfate and stirred.


Solutions and comparison solutions of samples analysed successively sprayed into the flame of a gas burner and measure the magnitude of the atomic absorption of the element. For each element perform at least two measurements and calculate the average value of absorption. The average value of absorption for solutions of the reference experiment is subtracted from the magnitude of the absorption of the element.

Calibration curve constructed in the coordinates: the magnitude of the absorption (average of measured values) — mass concentration of the element in the solution comparison.

The average value of absorption using a calibration chart, find the mass concentration of the element in the solution of the sample.

4.2. Analysis with atomization of the sample in the graphite furnace (HCA)

Determination of mass fraction of bismuth, tellurium, antimony, and platinum less than 0.005%, and arsenic is carried out by atomization of samples in the graphite furnace. The conditions of atomization in a furnace HCA-74 are given in table.7.

Table 7

At the stage of atomization using the mode «gas-stop» or «minimal flow of inert gas», as recommended in the operating instructions of the device.

Note. When using the graphite furnace other type of conditions the atomization of samples chosen experimentally.


Solutions and comparison solutions of samples analysed successively introduced into the graphite furnace, include a programming device and a heated oven for a given program (table.7). Account nonselective absorption carried out using a deuterium background corrector.

In the determination of arsenic using a graphite tube, treated with niobium oxide. After the introduction of the solution of comparison or solution of the sample in the graphite furnace is additionally injected 10·10cmof a solution of Nickel nitrate (matrix modifier).

In the determination of antimony in all analyzed solutions was added to a solution of tartaric acid. To this end, in a flask with a capacity of 25 cm,take 2 cmof the sample solution, add 2cmof a solution of tartaric acid and stir. For the dilution of solutions in the determination of antimony using a solution of tartaric acid, and in the determination of bismuth, arsenic, tellurium, and platinum — hydrochloric acid solution (1:20).

The measurement of the absorption and construction of calibration curve carried out in accordance with clause 4.1.

5. PROCESSING OF THE RESULTS

5.1. Mass fraction of the element-impurities () in percent is calculated by the formula

,

where is the mass concentration of the element was found in the calibration schedule, µg/cm;

 — the volume of the main solution of the sample, cm;

 — the coefficient corresponding to the degree of dilution of the basic solution;

 — the weight of the portion,

The result of the analysis taking the arithmetic average of the two results of parallel measurements.

5.2. The discrepancy between the results of parallel measurements (the difference between the smaller and larger of the two results of parallel measurements) and the variance analysis results (difference between smaller and larger of the two results of the analysis) must not exceed the allowable absolute values of the differences established with confidence probability of 0.95 and is shown in table.8.

Table 8

For intermediate values of the mass fraction of detectable elements permitted discrepancies are calculated by using linear interpolation.

6. THE CONTROL ACCURACY OF THE ANALYSIS

The control accuracy of the analysis carried out according to standard samples of composition of silver in accordance with claim 15 GOST 28353.0.