GOST 28353.2-89

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  ГОСТ 28353.2-89

GOST 28353.2−89 Silver. Method of atomic-emission analysis with inductive plasma

GOST 28353.2−89

Group B59

INTERSTATE STANDARD

SILVER

Method of atomic-emission analysis with inductive plasma

Silver. Method of atomic-emission analysis with inductive plasma

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 and the USSR Ministry of nonferrous metallurgy of the USSR

DEVELOPERS

Yu. a. Karpov, Dr. chem. Sciences (head of subject); O. A. Shiryaeva, PhD. chem. Sciences; L. N. Ryazanova, PhD. chem. Sciences; I. N. Vladimir; Sergey V. Sokolov; T. D. Gornostaeva, PhD. chem. Sciences; L. V. Potanin

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. INTRODUCED FOR THE FIRST TIME

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 specifies atomic emission (with an induction high-frequency plasma) 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 excitation of atoms of the sample in RF induction plasma and measuring the intensity of the analytical spectral line of the element during the spraying of the solution of the sample into the plasma. The relationship of the intensity of the line with 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, REAGENTS AND MATERIALS

Spectral-analytical complex, consisting of HF generator with a capacity of 0,8−1,5 kW plasma torch spray system, quantometer (polychromator) or monochromator with inverse linear dispersion is not worse than 0.5 nm/mm and photoelectric registration of radiation intensity, a control computer, display and printer.

Argon gas according to GOST 10157.

Analytical scales of the 2nd class.

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

Electric stove with a closed spiral.

The agate mortar.

Glasses glass with a capacity of 50, 100, 200, 250 and 300 cmaccording to GOST 25336.

Glass flasks with a capacity of 25, 50, 100 cmaccording to GOST 25336.

The corundum crucibles.

Pipettes with a capacity of 1, 2, 5 and 10 cmwith divisions according to GOST 29169, 29227 GOST — GOST 29230.

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

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, 1:10 and 1:100.

Nitric acid of high purity according to GOST 11125 and diluted 1:1, 1:10.

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

Barium peroxide is a high purity on the other 6−09−03−462.

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.

Antimony GOST 1089.

Cobalt GOST 123.

Nickel GOST 849.

Tellurium GOST 17614.

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

Manganese metal according to GOST 6008.

Arsenic metal, high purity for NTD.

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

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

Standard samples of composition silver.

Solutions containing 1 mg/cmof bismuth, copper, Nickel, lead, iron, cobalt, and arsenic: a portion of each of these metals with a weight of 100 mg dissolved in 10 cmof nitric acid (1:1) under heating. The solution was boiled to remove oxides of nitrogen, transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with water and mix.

Solutions containing 1 mg/cmgold, platinum, antimony and tellurium: a portion of each of these metals with a weight of 100 mg are dissolved in 20 cmof a mixture of hydrochloric and nitric acids (3:1) under 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.

Solutions containing 1 mg/cmzinc, and manganese: a portion of each of these metals with a weight of 100 mg 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 1 mg/CCof palladium: a sample of palladium weighing 100 mg was dissolved in 10 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 1 mg/cmrhodium, prepare one of the carried away

of the following ways:

1) a portion of rhodium (in powder form) weighing 100 mg was thoroughly stirred with a fivefold 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 273,4 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 cmplaced 1 cmsolutions of gold, platinum, palladium, rhodium, iron, copper, bismuth, tellurium, cobalt, Nickel, arsenic, antimony, lead, zinc and manganese, add 20 cmof hydrochloric acid, adjusted to the mark with water and mix. 1 cmof the solution contains 10 µg each of the identified elements; stable for months.

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 1 µg of each of the identified elements; is prepared on the day of application.

3. PREPARATION FOR ASSAY

3.1. Preparation of samples for analysis without separation of the silver

To perform the analysis selected for two silver sample weight 0.5−1.0 g each were placed in a glass with a capacity of 50−100 cmand clean the surface of silver GOST 28353.0.

The sample was dissolved with mild heating in 10 cmof nitric acid (1:1). After dissolution of silver was added 10 cmof water, filter the solution into a flask with a capacity of 50−100 cmthrough a double filter of «blue ribbon» with the addition of maseribane paper and washed precipitate containing gold and rhodium with a solution of nitric acid (1:10). The solution was transferred to a volumetric flask with a capacity of 50−100 cm, adjusted to the mark with water and mix (solution 1).

Solution 1 analyze for arsenic, bismuth, copper, cobalt, iron, manganese, Nickel, lead, palladium, platinum, tellurium, and zinc.

The filter with precipitate was placed in a beaker with a capacity of 50 cm, add 5 cmof a mixture of hydrochloric and nitric acids (3:1), incubated on the plate for 5−10 min at low heat, add 5 cmof hydrochloric acid solution (1:5) and filtered the solution into a flask with a capacity of 50 cm. The filter was washed with hydrochloric acid solution (1:10). The solution was transferred to a volumetric flask with a capacity of 25 cm, adjusted to the mark with water and mix (solution 2).

A solution of 2 assayed for gold content.

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

the second world war.

3.2. Preparation of samples for analysis with the separation of the silver

3.2.1. To perform the analysis selected two hanging silver weighing 0.5−2.0 g, each of which is placed in a beaker with a capacity of 250 cmand clean the surface of silver GOST 28353.0.

In a glass pour 10 cmof nitric acid (1:1) and dissolve the sample under low heat. 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 into 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 solution (filtrate 1) is evaporated at a moderate heating 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 and 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 CCof hot water and heated to dissolve the salts. 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). The filtrate is evaporated with moderate heat to a volume of 2−3 cm.

To the residue after evaporation was added 3 cmof hydrochloric acid, the solution transferred to a volumetric flask with a capacity of 25−50 cm, rinse the glass with water. The solution was adjusted to the mark with hydrochloric acid (1:5) and stirred. 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

.

3.3. Preparation of solutions comparison

3.3.1. For the determination of impurities in silver without separation of the silver solutions are used comparison, obtained by dissolving standard samples of composition silver.

To do this, select two sample standard samples of the composition by weight 0.5−1.0 g, mass fraction of impurities which are less than and greater than the expected mass fraction of impurities in the analyzed sample. The dissolution of batches and preparation of solutions is carried out according to claim 3.1 contemporaneously with the preparation of samples for analysis.

3.3.2. For the determination of impurities in silver with the separation of the silver solutions are used comparison, prepared from solutions A and B.

Solutions comparison with the mass concentration of determined elements 0,01; 0,03; 0,05; 0,10; 0,20; 0,40 and 1.00 µg/cmin volumetric flasks with a capacity of 50 cmimpose aliquote part of the solution A or B (tab.3), adjusted to the mark with hydrochloric acid (1:5) and stirred.

Table 3

4. ANALYSIS

Spectral-analytical complex is prepared to work include and take measurements of the analytical signal in accordance with the working manual of the device.

The wavelength of analytical spectral lines are given in table.4.

Table 4

Successively introduced into the plasma solutions and comparison with the help of a special program using the least squares method to get the numerical values of the coefficients of the polynomials approximating the calibration characteristics for each of the identified elements that enter into long-term memory of the computer.

The calibration characteristics is obtained in the coordinates: the intensity of the analytical line of the element minus the intensity of the emission spectrum for the solution in the reference experiment at the wavelength of the analytical line of the element mass concentration of the element in solutions comparison.

Solutions of the analyzed sample injected into the plasma and measure the intensity of the analytical lines of the determined elements. In accordance with the program for each solution, perform 3 measurements of the intensity and calculate the average value, which using the calibration characteristics find the concentration of element in ág/cmin the sample solution.

Note. During the transition from the analysis of nitrate of silver solutions by hydrochloric acid, and Vice versa, thoroughly rinse the spray system with a solution of nitric acid (1:10) and water to a negative reaction to silver ions or chloride ions, respectively.

5. PROCESSING OF THE RESULTS

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

,

where is the mass concentration of the analyzed element in the sample solution, µg/cm;

 — the volume of the sample solution, cm;

 — the weight of the portion of the sample,

The result of the analysis take the average of the two results of parallel measurements, each of which is made of a separate hinge.

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.5.

Table 5

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 GOST 28353.0.