GOST 17261-77

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  ГОСТ 17261-77

GOST 17261−77 Zinc. Spectral method of analysis (Changes No. 1−4)

GOST 17261−77*

Group B59

INTERSTATE STANDARD

ZINC

Method of spectral analysis.

Zinc.
Spectral method of analysis

AXTU 1709

Date of introduction 1979−01−01

APPROVED AND promulgated by the Decree of the State Committee of standards of the Council of Ministers of the USSR dated 20.12.1977 G. N 2949

LIMITATION of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

REPLACE GOST 17261−71

* EDITION (January 2000) with Amendments No. 1, 2, 3, approved in April 1983, may 1988 and November 1998 (ICS 7 to 83, 8−88, 2−99)

Change No. 3 adopted by the Interstate Council for standardization, Metrology and certification (report of the Technical Secretariat N 1 from 15.03.94)

The adoption of the changes voted:

The Change No. 4 adopted by the Interstate Council for standardization, Metrology and certification (Protocol No. 30 dated 07.12.2006). The state developer of Kazakhstan. By order of the Federal Agency for technical regulation and Metrology dated 25.12.2007 N 405-St introduced on the territory of the Russian Federation from 01.09.2008

N 4 a change made by the manufacturer of the database in the text IUS N 3, 2008


This standard specifies the spectral method for determination of iron, cadmium, copper, tin, lead and antimony in zinc brands CV0, CV, C0A, C0, C1, C2, C3, aluminum zinc brands CV0, CV, C0A, C0, C1, C2 according to GOST 3640−94 in the next interval mass fraction in percent:

iron from 0.001 to 0.2;

cadmium from 0.001 to 0.4;

of copper from 0.0005 to 0.1;

tin from 0.0007 to 0.05;

of lead from 0.002 to 3.0;

of antimony from 0.01 to 0.4;

aluminum 0.001 to 0.03.

The basis of spectral determination of impurities in zinc on the method of «three standards» with the excitation spectrum in the arc of an alternating current power of 5 A.

When disagreement in assessing the quality of zinc used spectral analysis method.

(Changed edition, Rev. N 1, 2, 3, 4).

1. GENERAL REQUIREMENTS

1.1. Samples produced according to GOST 3640−94.

Samples prepared in the form of cast rods of circular cross section with a diameter of 10 mm and a length of 50−100 mm.

From the zinc ingots average sample is taken in the form of chips, is melted in a preheated crucible at 430−450 °C and cast into a mold in the form of rods of specified dimensions or other dimension, depending on the size of the used standard samples.

(Changed edition, Rev. N 4).

1.1 a. General requirements for method of analysis according to GOST 25086−87 with the following additions.

1.1.1. The result of the analysis taking arithmetic mean value of parallel measurements, obtained in conditions of repeatability (the results are obtained by the same method on identical test items in the same laboratory by the same operator using the same equipment within a short period of time), if the condition of admissibility by the formula

, (1)

where and  — the results of two parallel determinations;

 — the value of the limit of repeatability, standardized methods of analysis (at confidence probability of 0.95).

If the discrepancy between the results of parallel measurements exceeds the value , normalized in the method of analysis, carried out for two parallel determination.

The result of the analysis take the average of results of four definitions, if the condition

, (2)

where and  — maximum and minimum values of the results of four definitions;

 — critical range.

The critical range is calculated by the formula

, (3)

where  — the ratio of the critical range for the four definitions (3,6);

 — standard deviation of repeatability.

If the range of the results of the four definitions () exceeds , for the result of the analysis taking the median of the results of four definitions: discard lowest () and highest () results and calculates the arithmetic mean value of the two remaining results definitions

.

1.1.2. The acceptability of analysis results, obtained in conditions of repeatability (the results are obtained by the same method, on identical test items in different laboratories with different operators using different equipment), estimated by comparing the difference of these results with the critical difference according to the formula

, (4)

where and  — the results of the analysis of the mass fraction of the designated component obtained in the first and second laboratories, respectively;

 — the critical difference.

The critical difference is calculated according to the formulas (5) to (7), when the results of the analysis calculated: as the arithmetical average of results of two parallel measurements in both laboratories to (5), as the arithmetic mean value of the results of two parallel definitions in the first lab and the average of results of four definitions in the second laboratory — (6); as the mean value of the results of the four definitions in both laboratories (7):

; (5)

; (6)

, (7)

where is the limit of reproducible, standardized methods of analysis (at confidence probability of 0.95);

 — the limit of repeatability, standardized methods of analysis (at confidence probability of 0.95).

The critical difference is calculated according to the formulas (8) and (9) when the results of the analysis calculated: as the arithmetical average of results of two parallel definitions in the first lab and as median in the second laboratory (8); taken as the mean value of the results of the four definitions in the first lab and as median in the second laboratory — (9):

; (8)

. (9)

The critical difference is calculated by the formula (10) when the results of the analysis are calculated as the median in both laboratories

. (10)

If the critical difference is not exceeded, it is acceptable both results of analysis performed by two laboratories, and as a final result of using their common arithmetic mean value.

Otherwise, investigate the cause of any discrepancies between the results of two laboratories (the presence of systematic errors of the analysis in one of the laboratories, the distinction between subjects tests) and apply the necessary corrective measures (joint sampling and sample preparation, participated in the reference laboratory, etc.) in accordance with GOST ISO 5725−6 (PP.5.3.3, 5.3.4).

1.1 a, 1.1 a.1, 1.1 a.2. (Changed edition, Rev. N 4).

1.1 a.3. The results of the analysis represent a numeric value, which must end with a digit of the same category as the numerical error is guaranteed when using the method of analysis (further referred to error analysis method) specified in this standard.

1.1.4. The recommended order of control accuracy and stability of results in the implementation of analysis methods in the laboratory are given in Appendix 1.

1.1 a.3, 1.1 a.4. (Added, Rev. N 4).

1.2. Safety requirements

1.2.1. Samples of zinc submitted for analysis should be stored in paper bags in racks or boxes equipped with ventilation.

1.2.2. In the operation of electrical appliances and electrical installations in the process of spectral analysis must comply with the rules of technical operation of electrical installations and safety rules at operation of electrical installations, approved by Gosenergonadzor, as well as the requirements of GOST 12.3.019−80, GOST 12.1.038−82.

All appliances should be equipped with devices for grounding — according to GOST 12.2.007.0−75и GOST 21130−75. Grounding shall conform to the requirements of electrical installation regulations, approved by Gosenergonadzor, and GOST 12.1.018−93, GOST 12.1.030−81.

1.2.3. To prevent contact with the air, ozone, nitrogen oxides, aerosols of metals and their oxides, metals emitted in the sources of spectra excitation and bad acting on the body in quantities exceeding the maximum allowable concentration, and also for protection from electromagnetic radiation and prevent sunburn by ultraviolet rays, each a source of excitation spectra should be placed inside of the device, equipped with an integrated exhaust air inlet and the protective screen according to GOST 12.1.010−76.

1.2.2, 1.2.3. (Changed edition, Rev. N 2).

1.2.3.1. The maximum permissible concentration of zinc oxide in the air of working zone of production areas is 0.5 mg/m.

1.2.3.2. Control of content of harmful substances in the air of working zone shall be carried out according to GOST 12.1.005−88. Analyses of air samples for the content of harmful substances in the air of working zone should be carried out according to the methods of determination of harmful substances in the air, approved by the Ministry of health, developed according to GOST 12.1.016−79.

(Changed edition, Rev. N 3).

1.2.4. Samples of zinc, the remainder of the analysis must be returned to the manufacturer (customer).

1.2.5. The laboratory of spectral analysis must have a common supply and exhaust ventilation in accordance with the requirements of GOST 12.4.021−75.

1.2.5.1. The laboratory room must be equipped according to the requirements of fire safety — GOST 12.1.004−91.

1.2.5.2. The laboratory must have a fire extinguisher and a box of sand in accordance with GOST 12.4.009−83.

1.2.5.3. Working in the spectral laboratory should be provided household premises in accordance with SNiP 2.09.04−87.

(Changed edition, Rev. N 3).

1.2.6. In the analysis of zinc, all work must be performed in a dry working clothes and protective equipment (gowns according to GOST 12.4.131−83, goggles according to GOST 12.4.013−85* respirators according to GOST 12.4.028−76) according to standard branch norms of free issue of workwear, footwear and protective equipment to workers and employees of the enterprises of nonferrous metallurgy, as approved by the State Committee for labor and social Affairs.
________________
* On the territory of the Russian Federation GOST R 12.4.013−97.

1.2.7. Working in the spectral laboratory needs to provide milk or an equivalent product according to the rules of free issue of milk or other equivalent food products to workers and employees in factories, workshops, stations and other departments with hazardous working conditions, approved by the State Committee for labor and social Affairs.

1.2.7.1. To work in the spectral laboratory allowed a person trained in safety rules in laboratories according to GOST 12.0.004−90.

2. APPARATUS, MATERIALS AND REAGENTS

The quartz spectrograph medium dispersion, allowing for a single exposure to the range of 230 to 380 nm, or a diffractive-type DFS-8 with three-lens Achromat illumination system of the slit and the three-step attenuator. Allowed to use devices with photoelectric registration of spectrum.

The generator is activated the arc AC.

Microphotometer of any type, allowing to measure the density of the blackening of analytical lines.

Laboratory electric furnace, mine for alloying of zinc shavings, allowing the temperature to 500 °C.

Mold for casting electrodes of round crosssection with a diameter of 10 mm and a length of 50−100 mm, is made of cast iron, steel and graphite or other sizes, depending on the size of the used standard samples.

Crucibles, graphite, graphite-chamotte and fireclay.

Files N 3 and 4 according to GOST 1465−80.

Grinding wheel rotating according to GOST 2424−83 or machine KP-35 for sharpening electrodes.

Spectrographic plates, the type II sensitivity 13−15 units or type S, sensitivity 10, SFC-02, the SFC-03, NT-2SV at THAT 6−43−1475−88.

Developer metalhydroxide; prepared as follows: mix fluids 1 and 2 in the ratio 1:2.

Solution 1.

Distilled water GOST 6709−72, up to 1 DM;

potassium carbonate (potash) according to GOST 4221−76 — 60

Solution 2.

Distilled water GOST 6709−72, to 2 DM;

metol according to GOST 25664−83 — 6 g;

hydroquinone according to GOST 19627−74 — 15 g;

sanitarily sodium (sodium sulfite) anhydrous GOST 195−77 — 90 g;

potassium bromide according to GOST 4160−74 — 6 g.

Allowed the use of other contrast-working developers, the composition of which is specified in the reference document on the production.

Fixer is acidic.

The time of development of photographic plates for 3−5 min at 18 °C.

Standard samples of zinc, manufactured in accordance with GOST 8.315−97.

Note. Allowed to use other devices and installations using a variety of excitation sources, other photographic plates, including imported, providing the metrological characteristics are not inferior to regulated by this standard.

Section 2. (Changed edition, Rev. N 1, 2, 3, 4).

3. ANALYSIS

3.1. Samples and standard samples, having the form of electrodes, sharpen on the «roof» (sharpened on two sides under an angle of 45° with the subsequent sharpening of the upper part of the electrode on the horizontal rectangular area with a width of 2−2,5 mm) and strengthen the tripod so to avoid shielding of the discharge. Allowed the sharpening of both electrodes on the hemisphere or on the lower plane and upper hemisphere.

When performing analysis on the instruments with photoelectric registration of spectrum allowed the use of samples, standard samples of a different shape and a different size.

On the end surface of electrodes should not be visible to the eye scratches, pits and other defects.

The distance between the electrodes is 2−3 mm.

The source of spectra excitation — arc alternating current power of 5 A.

(Changed edition, Rev. N 3).

3.2. The spectra are photographed on a quartz spectrograph medium dispersion or diffraction-type DFS-8 (the 600 lines/mm). The width of the slit of a spectrograph 0,015−0,020 mm front gap is installed a three-tier reliever. Are being used or other illumination system of the slit. Intermediate diaphragm — round.

When using devices with photoelectric registration of spectrum, you need to find the optimal conditions of excitation of spectra, allowing to obtain the necessary sensitivity and accuracy of analysis results.

The exposure time of 20−40 s depending on the sensitivity of the photographic plates.

For the determination of impurities in zinc uses pairs of lines given in table.1.

Table 1

Note. Allowed to use other free from the imposition of analytical lines, providing metrological characteristics of the results of the analysis, normalized in the standard.


(Changed edition, Rev. N 2, 3).

4. PROCESSING OF THE RESULTS

4.1. Two spectrum of standard samples and four samples of the spectrum photographed on the same photographic plate. With microphotometer measure the blackening of analytical lines of the designated element () and compare () and calculate the difference . The results of the photometry of the standard samples to build calibration graphs for each of the designated impurities in the coordinates .

While the axis of ordinate delay difference pucherani lines of impurities and comparison lines, and on the x — axis is the logarithms of the concentrations of the relevant impurities in the standard samples.

According to calculated values and on schedule define the mass fraction of impurities in the sample. Get the results of two parallel measurements.

Allowed for constructing the calibration graphs to use semilog paper to plot data in coordinates .

By the photoelectric registration of spectrum of the calibration graphs built in coordinates ,

where  — mass fraction of impurities in the reference sample;

 — the readings of the output of the measuring device, is proportional to the logarithm of the intensity of the lines defined by item and line comparison.

(Changed edition, Rev. N 2,

3).

4.2. Parallel definitions getting on the same photographic plate on the two spectrograms each with photographic registration of spectrum and in three dimensions each by the photoelectric registration.

Metrological characteristics of standards and methods of analysis must not exceed the values given in table.2.

Table 2

The values of metrological characteristics of standards and methods of analysis at confidence probability of 0.95

Percentage

The values of metrological characteristics and standards methods of analysis (with confidence probability of 0.95) for the intermediate mass fraction of the elements calculated by linear interpolation or according to the formulas:

for iron, copper, cadmium, tin, antimony

; (11)

; (12)

; (13)

; (14)

; (15)

— to lead in a mass fraction range from 0,0020% to 0.20% inclusive

; (16)

; (17)

; (18)

; (19)

; (20)

— for lead in the range of mass fractions of from 0.20% to 3.00% inclusive

; (21)

; (22)

; (23)

; (24)

; (25)

— for aluminum

; (26)

; (27)

; (28)

; (29)

, (30)

where  — standard deviation of repeatability;

 — standard deviation of reproducibility;

the limit value of the frequency of occurrence;

 — the value of the limit of reproducibility;

 — the margins of error;

 — arithmetic mean value or median of the results of the determinations;

 — arithmetic mean value of the results of the analysis.

(Changed edition, Rev. N 4).

Annex 1 (recommended). Control accuracy and stability of analysis results

Annex 1
(recommended)

1. Operational control of accuracy of analysis results

The control accuracy of the analysis results of zinc involves control of the accuracy, reproducibility, intermediate precision and repeatability.

The frequency of inspection is installed in each laboratory, depending on the number of running definitions of each element and the state of analytical works (change of reagents, solutions, equipment, long break from work, etc.).

When unsatisfactory results of the inspection control procedure the accuracy of the analysis is repeated. When you re obtaining negative results to investigate the cause of unsatisfactory results of control and eliminate them.

1.1. Operational control of reproduction

Samples for control samples are analyzed.

The ratio of control — limit of repeatability for the results of parallel measurements (2), or critical range according to 1.1 a.1 of this standard.

For control of reproduction compare differences of results of parallel measurements obtained by analysis of the sample.

1.2. Operational control of intermediate precision

Samples for control samples are analyzed.

The standard control limit of intermediate precision .

To control the intermediate precision compare two results of the analysis of the same samples obtained by the same method in accordance with this standard in different conditions (time, calibration, operator, equipment, reagents) in the laboratory.

The control result is considered satisfactory if the condition

, (1)

where and  — the results of the analysis of samples;

 — the value of the limit of intermediate precision.

The limit of intermediate precision does not exceed the limit of reproducible , standardized methods of analysis, and evaluated by the laboratory in accordance with GOST or ISO 5725−3, GOST ISO 5725−6.

1.3. Operational control of reproducibility

Samples for control samples are analyzed.

The standard control is a critical difference according to 1.1.2 of this standard.

To control the reproducibility comparing the results of the analysis of the same sample, done by the same method in accordance with this standard in different laboratories.

Control of reproducibility is carried out at occurrence of disputable situations:

— between the two laboratories;

— when checking the compatibility of the result obtained in the comparative tests (for accreditation of laboratories and inspection control).

1.4. Operational control of the correctness

The control of correctness carried out using the standard samples of composition of zinc, or alternative (independent) method.

The standard control is critical .

1.4.1. Operational control is correct according to standard samples

Models for control are standard samples developed in accordance with GOST 8.315.

Simultaneously with the analysis of samples in accordance with the methods of this standard, carry out the analysis of a standard sample of composition of zinc. The contents of the analyzed element in the standard sample and the sample must not vary by more than two times.

The result of the analysis of the standard sample compared with the certified characteristics of the element in the standard sample.

The control result is considered satisfactory if the condition

, (2)

where the result of the analyzed element in the standard sample, obtained from the results of single determinations;

 — certified the value of the element in the standard sample;

the critical value calculated according to the formula

, (3)

where is the standard deviation of reproducibility;

 — standard deviation of repeatability;

 — the number of results a single definition of a standard sample;

 — evaluation of the standard deviation certified value standard sample.

1.4.2. Operational control of the correctness of alternative (independent) method

Samples for control samples are analyzed.

Compare the results of the analysis of the same samples, obtained by two fundamentally different methods included in this standard, or by the standardized and any other certified method with error not exceeding the error of the standardized method.

The control result is considered satisfactory if the condition

, (4)

where and  — the results of the analysis obtained on the controlled and control methods, respectively;

the critical value calculated according to the formula

, (5)

where is the estimate of the total standard deviation of the controlled and control methods

, (6)

where and  — evaluation of the standard deviations of the controlled and control methods accordingly:

; (7)

, (8)

where and  — the standard deviation of reproducibility of the controlled and control methods, respectively;

and  — standard deviation of repeatability of the controlled and control methods, respectively;

and  — the results of a single controlled definitions and control methods respectively.

2. Control stability analysis results in the laboratory

Stability control indicators precision and accuracy of the results of the analysis in the laboratory is carried out according to GOST ISO 5725−6 (sect.6).

Appendix 1. (Added, Rev. N 4).



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M.: IPK Publishing house of standards, 2000