GOST R 56142-2014

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  ГОСТ Р 56142-2014

GOST R 56142−2014 Silver. Methods of atomic-emission analysis with arc excitation spectrum

GOST R 56142−2014

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

SILVER

Methods of atomic-emission analysis with arc excitation spectrum

Silver. Ark Method of atomic-emission analysis

OKS 77.120.99
AXTU 1709

Date of introduction 2015−09−01

Preface

1 DEVELOPED by the Open joint-stock company «Prioksky nonferrous metals plant», Federal state unitary enterprise «Moscow plant of special alloys», Open joint-stock company «Ekaterinburg plant for processing non-ferrous metals», Open joint stock company «Uralelectromed», 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 dated September 25, 2014 N 1223-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 sets the spectrographic method of atomic-emission analysis with arc excitation spectrum for determination of mass fraction of impurities, aluminum, bismuth, iron, gold, iridium, calcium, cobalt, silicon, magnesium, manganese, copper, arsenic, Nickel, tin, palladium, platinum, rhodium, lead, antimony, tellurium, zinc, and spectrometric method of atomic-emission analysis with arc excitation spectrum for determination of mass fraction of impurities, aluminum, bismuth, gallium, indium, Germany, iron, gold, indium, iridium, cadmium, calcium, cobalt, silicon, magnesium, manganese, copper, arsenic, Nickel, tin, palladium, platinum, rhodium, lead, selenium, antimony, tellurium, titanium, chromium, and 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 51652−2000 rectified ethyl Alcohol from food raw material. Specifications

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 334−73 Paper scale-coordinate. Specifications

GOST 5556−81 Wool medical hygroscopic. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 9147−80 Glassware and equipment lab porcelain. Specifications

GOST 14261−77 hydrochloric Acid of high purity. Specifications

GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

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 8.563, GOST R ISO 5725−1, GOST R 52361.

4 Accuracy (trueness and precision) of methods

4.1 accuracy rates of the methods

Indicators of accuracy of methods (spectrographic and spectrometer with an arc excitation spectrum) for GOST R ISO 5725−2, GOST R ISO 5725−3: the boundaries of the interval in which with probability P=0,95 is the absolute error of the results of the analysis (assigned error) , standard deviation of repeatability Sand intermediate precision S, the value of the critical range CR(4), intermediate precision limit Rand reproducibility limit R — depending on the mass fraction of the element are shown in table 1.


Table 1 — Indicators of accuracy of methods (R = 0,95)

For intermediate values of the mass fraction values in terms of accuracy find using linear interpolation according to the formula

, (1)

where A — accuracy rate as the result of analysis of X;

And, And — accuracy metrics corresponding to smallest and largest values of the interval mass fraction, which is the result of the analysis;

Since, Withthe smallest and largest values of the interval mass fraction, which is the result of the analysis.

4.1.1 Correctness

To estimate the systematic error of these methods for the determination of elements in silver are used as reference values certified values of mass fractions of elements in the state standard samples of composition silver GEO 7817−2000 (set SN) or other GEO, the next set of detectable elements and metrological characteristics.

The systematic error of the methods at a significance level of =5% is insignificant according to GOST R ISO 5725−4 for all the determined elements in silver at all levels of the designated contents.

4.1.2 Precision

4.1.2.1 the Range (Xmax-Xmin) four results of single definitions obtained for the same sample by one operator using the same equipment within the shortest possible time intervals may be greater than indicated in the table 1 critical range CRfor n=4 according to GOST R ISO 5725−6 on average not more than once in 20 cases.

4.1.2.2 within one laboratory, two test results (from four individual definitions of each) of the same sample obtained by different operators using the same equipment on different days, can vary with the excess specified in the table 1 the limit of intermediate precision R, GOST R ISO 5725−3 on average not more than once in 20 cases.

4.1.2.3 results of the analysis (of the four individual definitions of each) of the same samples obtained by two laboratories may vary with the excess specified in the table 1 reproducibility limit R according to GOST R ISO 5725−1 on average not more than once in 20 cases.

4.2 assessment of the admissibility of the results of parallel measurements and obtaining the final result of the analysis

4.2.1 acceptance of the results of parallel measurements was evaluated in accordance with GOST R ISO 5725−6 by mapping the range of these results (Xmax-Xmin) with a critical range CR(4), are shown in table 1.

4.2.2 If the range of the results of four parallel measurements (Xmax-Xmin) does not exceed the critical range CR(4), all results recognize acceptable and for the final result of the analysis taking the arithmetic mean of results of four parallel measurements.

4.2.3 If the range of the results of four parallel measurements exceeds CR(4), the analysis is repeated.

Calculated critical range for eight parallel measurements of CR(8) according to the formula

CR (8) = 4,3S(2)

where Sis the standard deviation of repeatability are given in table 1, %.

If the received eight parallel measurements, the value of (Xmax-Xmin) does not exceed the critical range CR(8), as a final result of the analysis taking the arithmetic mean of results of eight parallel measurements. Otherwise, as a final result of the analysis taking the median of the results of eight parallel measurements.

4.3 Control of accuracy of analysis results

4.3.1 Control intermediate precision and reproducibility

When monitoring intermediate precision (variable factors of the operator and time) is the absolute value of the difference between two results of analysis of the same sample obtained by different operators using the same equipment on different days, should not exceed the limit of intermediate precision R, listed in table 1.

Under the control of the reproducibility of the absolute value of the difference of the two results of the analysis of the same samples obtained by two laboratories in accordance with the requirements of this standard must not exceed the reproducibility limit Rgiven in table 1.

4.3.2 verification of correct

The checking is carried out by analyzing standard samples of composition silver. The samples used for control of correctness cannot be used to obtain the calibration dependencies.

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

The critical value K is calculated by the formula

, (3)

where is the absolute error of setting the reference (certified) value of the mass fraction of the element in the standard sample, %;

 — the boundaries of the interval of the absolute error of the result of the analysis (values shown in table 1), %.

5 Requirements

5.1 General requirements and safety requirements

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

5.2 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.

6 the Essence of the methods

Methods of analysis based on the evaporation and excitation of the atoms of the sample in arc discharge, measuring the intensity of radiation of atoms of determined elements and subsequent determination of the mass fraction of these elements using the calibration dependences obtained by standard samples of composition silver.

7 Spectrographic method of atomic-emission analysis with arc excitation

When the spectrographic method, using photographic registration of the emission spectra.

This method allows to determine the mass fraction of elements in the ranges shown in table 2, with indicators of the accuracy of the method of analysis specified in table 1.


Table 2 — Ranges of mass fraction of detectable elements

7.1 measurement Means, auxiliary devices, materials and reagents

Spectrograph with diffraction being a system of condensers, designed to produce spectra in the range 200−400 nm, reciprocal linear dispersion of 0.6−0.7 nm/mm.

Arc generator of alternating current with power up to 15 A.

Microdensitometer designed to measure the optical density (blackening) of spectral lines.

Scales non-automatic actions according to GOST R 53228 with limits of allowable absolute error of weighing of ±3 mg.

Resistance furnace.

Crucibles made of graphite OS.h. [1]*.
________________
* POS. [1]-[3], see Bibliography. — Note the manufacturer’s database.


Electrodes graphite OS.h. [2] 6 mm in diameter with a crater depth of 1−3 mm and a diameter of 4 mm.

Electrodes graphite OS.h. [2] 6 mm in diameter, sharpened to a hemisphere or truncated cone.

Photographic plates photographic spectrographic PFS-03 [3].

Contrast developer and fixer for photographic plates.

Electric stove with a closed spiral.

Glasses chemical resistant according to GOST 25336.

The pot and Cup porcelain GOST 9147.

Hydrochloric acid OS.h. according to GOST 14261, diluted 1:1.

Rectified ethyl alcohol according to GOST R 51652.

Distilled water according to GOST 6709.

Surgical tweezers.

Cotton fabric according to GOST 29298.

Adhesives according to GOST 5556.

Paper scale-coordinate according to GOST 334.

Samples for calibration (samples of silver with the previously established values of the mass fraction of impurity elements).

Standard samples of composition silver GEO 7817−2000 (set SN), or others of equal composition of the elements and accuracy.

Allowed the use of other measurement means, auxiliary devices, materials and reagents, subject to obtaining accuracy rate that rivals those in table 1.

7.2 Sampling and sample preparation

7.2.1 Samples for analysis are taken in accordance with the standard, establishing the requirements for chemical composition of silver.

7.2.2 Samples of silver could enter the analysis in the form of ribbon, wire, shavings, sponge, powder, granules, crystals.

7.2.3 Samples received for analysis in the form of tape, wire, pellets or chips placed in a porcelain Cup or a glass Cup, add a solution of hydrochloric acid 1:1 and boiled for 5−10 min. the resulting solution was decanted, the sample was washed with distilled water by decantation 4−5 times and dried in air.

Samples of the powder, sponge and crystals acid is not treated.

7.2.4 From samples of silver entering the analysis are taken four sample, from the samples to the calibration or standard samples — two sample weighing 200 mg each. Allowed the capture of different portions of the mass subject to receipt of the accuracy rate that rivals those in table 1.

7.2.5 Sample is transferred to a graphite crucible, is fused in resistance furnace and get the persimmons. Received kinglet rubbing alcohol or boil in a solution of hydrochloric acid 1:1 at p.7.2.3. Allowed fusion of the sample directly in the crater of the lower electrode.

7.3 preparing the measurements

7.3.1 Equipment ready to work according to the instructions. The wavelengths of the analytical lines and background, the working modes of the instruments recommended to perform the analysis presented in tables 3 and 4, respectively. For each designated item, choose one of the recommended wavelengths. The use of other lines and operating modes subject to receipt of the accuracy rate that rivals those in table 1.

7.3.2 electrode adapters and devices are cleaned with alcohol from surface contamination.

7.3.3 Include water cooling of the electrode holders.

7.3.4 Graphite crucibles and graphite electrodes prior to use, calcined for 5−10 s at a current of 5−6 A.

7.3.5 Prepared for analysis the weight and / or bead of silver is placed in a graphite crater electrode. Contradictator is a graphite rod sharpened to a hemisphere or truncated cone.

7.3.6 the Interelectrode gap set on the magnified image of the arc on the screen, the intermediate diaphragm of 5 mm and maintain strictly constant, adjusting it throughout the exposure.


Table 3 — wavelengths of the analytical lines of the elements

Table 4 — Recommended operation modes

7.4 measurements

7.4.1 To obtain a calibration curve using standard samples of composition of silver or samples for calibration. Spectra of each standard sample (sample for calibration) and a test sample is photographed under the same conditions. For each standard sample (for calibration) get two, and for the sample analyzed four spectrograms.

7.4.2 the copper content of more than 0,012% and iron more than 0.002 per cent use a three-step attenuator.

7.4.3 photographic Plates showing, rinsed in water, fixed, washed in running water and dried.

7.4.4 using microdensitometry on each spectrogram to measure the blackening of analytical lines of the designated element of S, (table 3) and the surrounding background S(minimum blackening near the analytical line from either side, but with the same in all spectra on the same photographic plate) or line comparison S. Calculate the difference of pochernenija S=S-S(S). From the obtained values of S are transferred to the values of Ig(I/I) using the table given in the Appendix A. Using values from the IgC and Ig(I/I) obtained for standard samples built on a scale-coordinate paper calibration curve in the coordinates (IgC, Ig(I /I), where With — mass fraction of the element in the standard sample (the sample for calibration). Four values of Ig(I/I)1Ig(I/I)4 obtained four spectrograms for each of the designated element, find the schedule of values X — values of the logarithm of the mass fraction. According to the formula With a=10calculated values of mass fraction of impurities, the results of parallel measurements.

The use of other lines, as well as the procedure of constructing the calibration graphs with the use of appropriate programs for computing machinery subject to receipt of the accuracy rate that rivals those in table 1.

7.4.5 In the upper end of the range of mass fractions allowed the construction of calibration graphs in the coordinate S-IgC, where S is the difference of pochernenija analytical lines and comparison lines (silver).

7.4.6 According to the calibration schedule, with four parallel values of Ig(I/I) or S, respectively, obtained four spectrograms for each sample, find the four results of parallel measurements of the mass fraction of each element in the sample. The result of the analysis is calculated as the arithmetic mean of four parallel measurements.

8 Spectrometric method of atomic-emission analysis with arc excitation

When the spectrometric method, using a photoelectric method of recording emission spectra.

The method allows to determine the mass fraction of elements in the ranges given in table 5.


Table 5 — Ranges of mass fractions of the identified elements

8.1 measurement Means, auxiliary devices, materials and reagents

The optical emission spectrometer with an inverse linear dispersion of 0.6 nm/mm, spectral region 170−500 nm or spectrograph with a reciprocal linear dispersion of 0.6 nm/mm, spectral region, 170−500 nm and check the diode matrix (Maes).

Arc generator AC current up to 15 A.

The multichannel analyzer of atomic emission spectra (Maes) with the software „Atom“.

Scales non-automatic actions according to GOST R 53228 with limits of allowable absolute error of weighing of ±3 mg.

Resistance furnace.

Electric stove with a closed spiral.

Crucibles, made of graphite OS.h. [1].

Electrodes graphite OS.h. [2] 6 mm in diameter with a crater depth of 1−3 mm and a diameter of 4 mm.

Electrodes graphite OS.h. [2] 6 mm in diameter, sharpened to a hemisphere or truncated cone.

Glasses chemical resistant according to GOST 25336.

Hydrochloric acid OS.h. according to GOST 14261, diluted 1:1.

Rectified ethyl alcohol according to GOST R 51652.

Distilled water according to GOST 6709.

The pot and Cup porcelain GOST 9147.

Surgical tweezers.

Cotton fabric according to GOST 29298.

Adhesives according to GOST 5556.

Samples for calibration (samples of silver with the previously established values of the mass fraction of impurity elements).

Standard samples of composition silver GEO 7817 (set SN), or others, are not inferior to the 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 1.

8.2 Sampling and sample preparation

8.2.1 Selection and preparation of samples for analysis is carried out at 7.2

8.3 Preparation of equipment for measurement

Equipment ready to work according to the instructions. Operating modes of the spectrometer are given in table 6. The use of other operating modes subject to receipt of the accuracy rate that rivals those in table 1.


Table 6 — Recommended operating modes of the spectrometer

8.4 measurements

8.4.1 Prepared for analysis a portion of sample or standard sample is placed in the recess of the lower graphite electrode. The counter is graphite electrode, sharpened to a truncated cone or hemisphere.

The interelectrode gap of 1.5−2.5 mm set at an intermediate aperture with a height of 5 mm, keeping constant throughout the exposure. Between the electrodes ignite the arc AC.

8.4.2 parameters of the multichannel analyzer of atomic emission spectra (Maes):

the unit exposure time is 250 MS;

savings in cycle — 120;

cycle duration — 120;

full exposure — 30 sec.

Check the dark current is performed twice before the start and regularly every 30−40 min during operation.

As a reference line used line carbon 247,85 nm or line of silver 330,57 nm.

8.4.3 During the arc discharge is automatically measured intensity of analytical lines of each of the identified elements, comparison lines and the background under the maximum of the peak at the corresponding wavelengths.

To obtain a calibration based on measurements taken of the intensity of the analytical lines of the determined elements, the lines of comparison and background for standard samples (the samples for grading) structure of silver. The calibration graphs are automatically generated in accordance with the analytical program „the Atom“ in the coordinates DS-Igl, where DSis the logarithm of the certified value determined by the impurities in the standard sample, the Igl is the logarithm of the intensity of the analytical lines given a line of comparison or background.

8.4.4 In accordance with the analytical program, the evaluation of the content of the element is calculated automatically with the information output to the monitor. The analysis result should be the arithmetic mean of the four results of parallel measurements with registration of result of analysis to the printer either in a special journal, subject to the requirements of section 4.

8.4.5 the wavelengths of the analytical lines is recommended to perform the analysis shown in table 3.

The use of other analytical lines and operating modes and parameters Maes, subject to receipt of the accuracy rate that rivals those in table 1.

Annex a (mandatory). The table of values Ig (I (l)/I (f)), corresponding to the measured values of Delta S/"gamma»

Appendix A
(required)

The table of values Ig (I/I), the corresponding measured values of S/

Table A. 1 serves for transmission of measured values S/and lgI/I. The table contains the results of the calculation in the formula

lg I/I=Ig(10-1), (A. 1)

where S is the difference of the density of pochernenija on the plate;

 — contrast ratio.

We denote the total intensity of the line with the background I, the intensity of the background under the high line in the absence of line I. As I=I+I, the ratio of the intensity of line Ito the background intensity is determined by the formula

I/I=I/I-1, (A. 2)

If the conditions of photographing the spectrum chosen so that the blackening line with the background 'sbackground and in the absence of the line Slie in the normal range,

lg I/I=S/, where S=S-S(A. 3)

Hence, using the expression I/I=I/I-1, we get

lg I/I=lg (I/I-1)=lg(10-1). (A. 4)

Table A. 1 covers the most important practices for analytical work values S/from 0.05 to 1.90.

The table consists of two parts: the part involving values S/from 0.05 to 0.99 and portions of the value S/from 1.00 to 1.90.

In the first part of the table in the first column are the values S/with two decimal places, the figures in the heads of others count from 0 to 9 indicate the third decimal place of the value S/.

For example, S/=0,537: find the first column value of 0.53, and in the graph with figure 7 to determine the corresponding value of the logarithm lg I/I=0,388.

The second part of the table built in a similar way with the difference that the first column lists values of S/with one decimal place and the numbers in the heads of other boxes represent the second after the decimal point, the sign of the value S/.

For example, S/=1.36 in the first column find the value of 1.3, in the graph from figure 6 find the value of logarithm lg I/I=1,341.

For values of S/smaller than had 0.301, the value of lg I/Iis negative — the minus sign over the characteristic (±1…).

As lg I/I=S/, then the table can be used to find the value of lg I/Icorresponding to the values of lg I/Iwith any method of measurement.

If the contrast ratio is not measured, instead of the values S/in the table use the values of S, use this table in a similar way. If the measured value S=and 0.674 in the first column find the value of 0.67 in column 4 determine the meaning of the logarithm of 0,571.

It should be noted that the found thus the value of 0,571 is not a lg I/I, a Ig(10-1). The precision of the analysis by the method of «three standards» the fact is almost no effect.


Table A. 1 — Values of lg (I/I), the corresponding measured values of S/

End of table A. 1

________________
* The values shown the table correspond to the original. — Note the manufacturer’s database.

Bibliography