GOST 28353.1-89

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  ГОСТ 28353.1-89

GOST 28353.1−89 Silver. Method of atomic-emission analysis

GOST 28353.1−89

Group B59

INTERSTATE STANDARD

SILVER

Method of atomic-emission analysis

Silver. Method of atomic-emission 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. P. Tomaszewski (chair), V. M. Andreev, G. G. Pirozhnikova; T. A. Kislitsina

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 13638.1−79

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 method of atomic emission 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 excitation of the atoms of the sample of globules (liquid drops of the melt) in the arc discharge, the photographic registration of the spectrum and then measure the intensity of spectral lines of the identified elements. The relationship of the intensity of the line with a mass fraction of the element in the sample set with the help of calibration curve by standard samples.

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 security requirements — according to GOST 28353.0.

2. APPARATUS, REAGENTS AND MATERIALS

Spectrograph medium dispersion with one-, three-lens Achromat lighting system.

The generator that provides the arc discharge of alternating current.

Tripod with forced cooling.

Microphotometer.

Spectrographic plates of types 1, 2, 3, ES, or other contrasting materials.

Electric stove with a closed spiral.

Resistance furnace with a power of 5 kW.

Electrodes, carbon, spectral-pure:

the lower diameter of 6−8 mm, a length of 30−50 mm with a conical recess 1 mm;

the top — diameter of 6−8 mm, a length of 30−50 mm, sharpened to a truncated cone.

Metallity.

Grinding machine carbon electrodes.

Analytical scales of the 2nd class.

The three-stage attenuator.

Crucibles porcelain with GOST 9147.

Developer:

Fixer:

The graphite cups are made of spectral pure graphite.

Hydrochloric acid of high purity according to GOST 14261, diluted 1:1.

Standard samples of composition silver.

3. PREPARATION FOR ASSAY

From each sample take at least eight batches weighing 200 mg of each standard sample, with at least four batches weighing 200 mg. the surface of the silver clean in accordance with GOST 28353.0. Then each sample was placed in a clean graphite Cup and melted in a resistance furnace for 5 s in the bead.

4. ANALYSIS

Each bead is placed in the conical recess of the lower carbon electrode. The upper electrode is a carbon rod, sharpened to a truncated cone.

Spectra of standard samples and samples are photographed under the same conditions.

Conditions of photographing of the spectra:

the width of the slit of a spectrograph — 0.015 mm; exposure — 25−60 s; distance between the electrodes is 1.5−2 mm are placed on the template.

As a source of spectra excitation is used in arc AC current 5−6 A.

Photographing spectra is carried out in two regions of the spectrum: when setting the scale of wavelengths at 325 and 260 nm. For each region of the spectrum receive two spectrograms for each standard sample and four of the spectrogram for each trial. When determining the mass fraction of copper of more than 0,012% and iron more than 0.002% of the spectra photographed through a three-stage attenuator. Photographic plates showing, rinsed in water, fixed, washed in running water and dried. The wavelengths of the analytical lines is recommended to perform the analysis, are given in table.3.

Table 3

5. PROCESSING OF THE RESULTS

5.1. On each spectrogram to measure the blackening of analytical lines of the designated element (table.3) and nearby background (minimum blackening near the analytical line of the element on either side, but with the same in all spectra on the same photographic plate). Calculate the difference of pochernenija . The values of and obtained two spectrograms for each standard sample, find the arithmetic mean . From the average values for standard samples and obtained four spectrograms for each of the analyzed samples are transferred to corresponding values of the logarithms of relative intensity , in accordance with Annex GOST 13637.1.

Calibration curve constructed in the coordinates: logarithm of relative intensity is the logarithm of the mass fraction of the element in the standard sample . For the calibration graph and the values to find the mass fraction of the element in percent (four parallel determinations).

When working in the field of normal pucherani allowed to build a calibration curve in the coordinates .

The result of the analysis taking the arithmetic average of the four results of the parallel objectified

Eleni.

5.2. Discrepancies in the results of parallel measurements (the difference between the highest and lowest of the four 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.4.

Table 4

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.