GOST R 56307-2014

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  ГОСТ Р 56307-2014

GOST R 56307−2014 Silver. Method of atomic-emission analysis with spark excitation spectrum

GOST R 56307−2014

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

SILVER

Method of atomic-emission analysis with spark excitation spectrum

Silver. Method of spark atomic-emission analysis

OKS 39.060

Date of introduction 2015−07−01

Preface

1 DEVELOPED by the Open joint-stock company «Prioksky factory of nonferrous metals», Open joint stock company «Krasnoyarsk factory of nonferrous metals named after V. N. Gulidova», State scientific center State scientific-research and design Institute of rare metals industry «Giredmet"

2 SUBMITTED by the Technical Committee on standardization TC 304 «Noble metals, alloys, industrial jewelry products, secondary resources containing noble metals"

3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology of December 12, 2014 N 1991-St

4 INTRODUCED FOR THE FIRST TIME


Application rules of this standard are established in GOST R 1.0−2012 (section 8). Information about the changes to this standard is published in the annual (as of January 1 of the current year) reference index «National standards» and the official text changes and amendments — in monthly information index «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a future issue of information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet (gost.ru)

1 Scope

This standard applies to silver with a mass fraction of silver is not less than 99.5%.

The standard specifies atomic emission (spark excitation and photoelectric registration of spectrum) method for the determination of impurities, aluminum, bismuth, gallium, indium, Germany, iron, gold, indium, cadmium, cobalt, silicon, magnesium, manganese, copper, arsenic, Nickel, tin, palladium, platinum, rhodium, lead, selenium, sulfur, antimony, tellurium, titanium, chromium, zinc in silver. Requirements to chemical composition set in silver GOST 28595.

2 Normative references

This standard uses the regulatory references to the following standards:

GOST R 8.563−2009 State system for ensuring the uniformity of measurements. Techniques (methods)of measurements

GOST R ISO 5725−1-2002 Accuracy (trueness and precision) of methods and measurement results. Part 1. General provisions and definitions

GOST R ISO 5725−2-2002 Accuracy (trueness and precision) of methods and measurement results. Part 2. The basic method for the determination of repeatability and reproducibility of a standard measurement method

GOST R ISO 5725−3-2002 Accuracy (trueness and precision) of methods and measurement results. Part 3. Intermediate indicators the precision of a standard measurement method

GOST R ISO 5725−4-2002 Accuracy (trueness and precision) of methods and measurement results. Part 4. The main methods of determining the correctness of a standard measurement method

GOST R ISO 5725−6-2002 Accuracy (correctness and precision) of methods and measurement results. Part 6. The use of precision values in practice

GOST R 52361−2005 Control of the analytical object. Terms and definitions

GOST R 52599−2006 Precious metals and their alloys. General requirements for methods of analysis

GOST R 53228−2008 Scales non-automatic actions. Part 1. Metrological and technical requirements. Test

GOST 5556−81 Wool medical hygroscopic. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 10157−79 Argon gaseous and liquid. Specifications

GOST 14261−77 hydrochloric Acid of high purity. Specifications

GOST 18300−87 ethyl rectified technical. Specifications

GOST 28595−90 Silver bullion. Specifications

GOST 29298−2005 cotton and mixed household. General specifications

Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or in the annual information index «National standards» published as on January 1 of the current year, and the editions of the monthly information index «National standards» for the current year. If replaced with a reference standard, which was given an undated reference, then it is recommended to use the current version of this standard, taking into account all enabled in this version modifications. If replaced with a reference standard, which is given a dated reference, it is recommended to use the version of this standard referred to above by year of approval (acceptance). If after approval of this standard in the reference standard, which is given a dated reference, a change affecting a provision to which reference, the provision is recommended to be applied without taking into account this change. If the reference standard is cancelled without replacement, the position in which reference is made to him, recommended to be used in part not affecting this link.

3 Terms and definitions

This standard applies the terminology according to GOST R ISO 5725−1, GOST R 8.563, GOST R 52361 and recommendations [1].

4 the essence of the method

The method of analysis is based on the evaporation and excitation of the atoms of the sample in the spark discharge, the photoelectric registration of spectrum, measuring the intensity of the analytical lines of the determined elements-impurities and the background, and the subsequent determination of content of impurities in the calibration characteristics. The method allows to determine the mass fraction of impurity elements in the ranges shown in table 1, with indicators of the accuracy of the method of analysis specified in table 2.


Table 1 — Ranges of definition of mass fraction of impurity elements

Percentage

5 Accuracy (trueness and precision) of the method

5.1 indicators of the accuracy of the method

Indicators of accuracy of the method according to the GOST R ISO 5725−2, GOST R ISO 5725−3: the boundaries of the interval in which with a probability of 0.95 is the absolute error of the results of the analysis (assigned error) , standard deviation of repeatability and intermediate precision , the values of the critical range , intermediate precision and reproducibility limit depending on the mass fraction of the element-impurities are shown in table 2.


Table 2 — Indicators of accuracy of the method when p = 0.95

Percentage

5.2 Correctness

To estimate the systematic error of the present method of determining the elements of the impurities in the silver is used as a reference certified value mass fraction of elements in the state standard samples (GSO) composition silver GEO 7817 (set SN) or other GEO, whose set of designated elements-impurities and metrological characteristics.

Systematic error of the method at a significance level of 5% according to GOST R ISO 5725−4на all defined levels of mass fraction of impurity elements in silver insignificant.

5.3 Precision

5.3.1 Range () four results of determinations obtained for the same sample by one operator using the same equipment within the shortest possible time intervals that may exceed the specified in table 2, the critical range for 4 on average not more than once in 20 cases.

5.3.2 within one laboratory two results of the analysis of the same sample obtained in accordance with sections 7−10 of this standard, different operators using the same equipment on different days, can vary with the excess specified in table 2 of the limit of intermediate precision on the average not more than once in 20 cases.

5.3.3 Results of the analysis of the same samples, obtained in two laboratories, in accordance with sections 7−10 of this standard may vary in excess of the limit of reproducibility indicated in table 2, on average not more than once in 20 cases.

For intermediate values of mass fraction of impurity elements the values of precision find using linear interpolation according to the following formula

, (1)

where  — the indicator of the accuracy of the analysis result;

, the values of precision, corresponding to the lower and upper level mass fraction of detectable elements, between which is the result of the analysis;

 — the result of the analysis;

, values of the lower and upper levels of the mass fraction of elements, between which there is the result.

6 Requirements

6.1 General requirements and safety requirements

General requirements for method of analysis, the requirements for security of works — according to GOST R 52599.

6.2 qualifications of performers

The analysis allowed persons over the age of 18, trained in the prescribed manner and allowed to work independently on used equipment.

7 measuring instruments, auxiliary equipment, materials and reagents

Optical emission spectrometer with spark excitation source spectrum and the working wavelength range 120−700 nm, equipped with a computer and appropriate software.

Laboratory scales in accordance with GOST R 53228 with a limit of permissible absolute error of less than ±0.01 g.

Press and mold with a diameter of 40 mm.

Milling machine.

Medical absorbent cotton wool GOST 5556.

Distilled water according to GOST 6709.

Hydrochloric acid according to GOST 14261.

Argon gaseous and liquid GOST 10157.

Cotton fabric according to GOST 29298.

Rectified ethyl alcohol according to GOST 18300.

Standard samples of composition silver GEO 7817 (set SN) or the other WITH equal composition of impurity elements and precision.

Allowed the use of other measurement means, auxiliary devices, materials and reagents, subject to obtaining accuracy rate that rivals those in table 2.

8 Selection and preparation of samples

8.1 Sampling for analysis is carried out in accordance with the requirements of GOST 28595. Requirements for the size and mass of the samples are determined depending on the used spectrometer.

8.2 Samples of silver could enter the analysis in the form of ingots, rods, plates, strips, shavings, sponge, powder.

8.3 Samples in the form of strips, plates, shavings boiled in a solution of hydrochloric acid diluted 1:1 for 3−5 min to remove surface contamination. The resulting solution was decanted, the sample was washed 4−5 times with distilled water by decantation and dried in air.

Samples of the powder and sponge not treated with acid.

8.4 the surface of the rods and plates should be flat, and processed by cutting or grinding, the tape surface should be smooth and without delamination. Samples in the form of a monolithic specimen having not less than one flat surface treated with a milling machine. On the treated surface should be free of holes, scratches, cracks, and slag inclusions.

Directly before analysis allowed samples and standard samples wipe clean with a cloth moistened with alcohol.

8.5 From the sample in the form of chips or powder taken weighed 20−30 g and pressed with a force equal to 600 kN per tablet.

9 Preparation of equipment for measurement

Spectrometer ready to work according to the operating documents of the device.

The recommended mode of operation of the spectrometer:

the discharge frequency of 300 Hz;

— capacity — (2−5) UF

— inductance — µh 130;

— purging with argon — 3.

The wavelengths of the analytical lines, background, and line of internal standard is recommended to perform the analysis shown in table 3.


Table 3 — wavelengths of the analytical lines

In nanometers

Note — the use of other modes and the analytical lines subject to receipt of the accuracy rate that rivals those in table 2.

10 measurements

To obtain the calibration dependencies consistently reinforce the cell spark discharge standard samples of composition of silver and laid in the spectrometer’s program, perform measurements of the intensity of the analytical lines of the determined elements, background, and lines the internal standard. For graduation choose three or more standard samples of composition of the silver so that the value of the content of each analyzed element-impurities in the sample was within the range between the highest and lowest values of the mass fraction of this element in the standard samples. For each standard sample perform measurement in four different points of the surface.

The calibration relationships are obtained in the coordinates: the average value of the intensity of the analytical lines of the determined elements (including the background or comparison lines) of the four points of the sample surface — the mass fraction of the element in the standard sample.

Measured intensity of analytical lines of the determined elements, background, and lines the internal standard in four points on the surface of the sample. Embedded in the spectrometer program using a calibration dependencies get four results of parallel measurements in the sample.

11 Evaluation of the acceptability of the results of parallel measurements and obtaining the final result of the analysis

The acceptability of the results of parallel measurements was evaluated in accordance with GOST R ISO 5725−6 by matching range, results () with the critical range , the values of which are given in table 2 or calculated by the formula (1).

If the range of the four results of the parallel definition (a) does not exceed the critical range , all the results and recognise acceptable for the final result of the analysis taking the arithmetic mean of the four results of parallel measurements.

If the range of the four results of parallel measurements exceeds , spend four parallel determinations.

The critical range is calculated by the following formula

, (2)

where is the number of parallel definitions;

 — coefficient depending on the number of individual analysis results, obtained in conditions of repeatability and confidence probability of 0.95. For eight parallel measurements of 4.29;

 — standard deviation of repeatability are given in table 2.

If the received eight results of parallel measurements, the value () does not exceed the critical range , as a final result of the analysis taking the arithmetic mean value of the eight results of parallel measurements. Otherwise, as a final result of the analysis taking the median of the eight results of parallel measurements. The lower bits of the numerical result and the numeric values of the accuracy metrics should be the same.

12 Control of accuracy of analysis results

12.1 Control of intermediate precision and reproducibility

When monitoring intermediate precision (taking into account the influencing factors of time, operator) absolute difference of the two results of the analysis of the same sample obtained by different operators using the same equipment on different days, should not exceed the limit of intermediate precision specified in table 2 or calculated by the formula (1).

Under the control of the reproducibility of the absolute disparity of the two results of the analysis of the same samples, obtained in two laboratories, in accordance with the requirements of this standard must not exceed the limit of reproducibility shown in table 2 or calculated by the formula (1).

12.2 verification of correct

The checking is carried out by analysis of standard samples (CO) composition silver. The samples used for control of correctness should not be used to obtain the calibration dependencies.

When checking the difference between the analysis result and the accepted reference (certified) value of the content of element impurities in the standard sample should not exceed a critical value .

Critical value calculated by the following formula

, (3)

where  — the error of setting the reference (certified) value of mass fraction of element-impurities in.

 — the indicator of the accuracy of the analysis result, the corresponding certified value.

Bibliography

__________________________________________________________________________
UDC 669.231:543.06:006.354 OKS 39.060

Keywords: silver, silver bullion, methods of analysis, impurities, atomic emission method of analysis spark excitation spectrum, spark, standard samples of composition, correctness of the method of analysis, precision analysis method, the absolute error, limit of repeatability, limit of intermediate precision, limit of reproducibility, control of accuracy of analysis results