GOST 28473-90

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  ГОСТ 28473-90

GOST 28473−90 Iron, steel, ferroalloys, chromium and manganese metal. General requirements for methods of analysis

GOST 28473−90

Group B39

INTERSTATE STANDARD

CAST IRON, STEEL, FERRO-ALLOYS, CHROMIUM, MANGANESE METAL

General requirements for methods of analysis

Iron, steel, ferroalloys, metal chromium and metal manganese.
General requirements for methods of analysis

ISS 77.040.30
AXTU 0809

Date of introduction 1991−07−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR

DEVELOPERS

V. P., Zamaraev, N. Panarin, M. S. Dimova, R. D. Malinin, V. T. Ababkov, A. A. Sakharov, L. N. Dimitrov, V. Stepanovski, E. N. Kotlyarevskaya

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 23.03.90 N 526

3. The standard fully complies ST SEV 463−86, ST SEV 487−77

4. INSTEAD 20560−81 GOST, GOST 27349−87, GOST 2604.0−77

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. The expiration time limit is removed by the Resolution of Gosstandart of the USSR from 03.06.91 N 776

7. REISSUE

1. This standard specifies the General requirements for chemical and physico-chemical methods of analysis of iron, steel, ferroalloys, chromium and manganese metal.

2. The selection and preparation of samples of iron, steel, ferroalloys, chromium and manganese metal is carried out according to GOST 7565, GOST 17260 and normative-technical documentation for specific products.

3. For analysis is used:

cylinders, beakers, flasks and test tubes according to GOST 1770;

burettes, pipettes according to GOST 29251, GOST 29227;

glassware and equipment glass according to GOST 25336;

porcelain crucibles, boats, etc. according to GOST 9147;

crucibles and cups made of platinum according to GOST 6563;

the dishes of glassy carbon brand SU-2000;

standardized means of measuring the analytical signal;

reagents qualifications not lower than «pure for analysis» (h. e. a);

other means of measurement with metrological characteristics, equipment with technical characteristics as the standardized means of measurement, other laboratory glassware, poverenny according to GOST 8.234, and reagents for quality not lower than the above.

The use of reagents of higher qualifications or lower qualifications should be specified in the relevant standard methods of analysis.

4. The metals used for the preparation of standard solutions must contain the base metal is not less than 99.9%.

5. For the preparation of aqueous solutions of reagents and tests used distilled water according to GOST 6709 or deinotherium water quality is not below the specified standard, unless stipulated other requirements in the standard methods of analysis.

6. In the preparation of reagents solutions and analysing, after each addition of reagents the solution was stirred.

7. The concentration of solutions Express:

mass concentration, g/DMg/cm;

molar concentration — mol/DM;

molar concentration of equivalent (normality) mol/DM(n);

mass fraction (mass of substance in grams referred to 100 g of solution or 100 g of substance), %;

the volume fraction (the volume of material in cubic centimeters, is related to 100 cmof solution, gas mixture), %.

The content of a substance in solution expressed as a density , g/cm.

The contents of the element in the iron, steel, ferroalloys and metals to Express a mass fraction, %

8. In terms of the «diluted 1:1, 1:2, etc.» and the notation «(1:1), (1:2) etc.» the first digits represent the volumetric part of the dilute reagent (e.g. concentrated acids), the second volume of the solvent (e.g. water).

If the standard does not indicate the concentration of the acid or an aqueous solution of ammonia, then use concentrated acid or concentrated aqueous ammonia solution.

9. The concept of «room temperature», «warm» or «hot» water (or solution) means that the fluid has a temperature of more than 15−25 respectively, from 40 to 75 and above 75 °C (GOST 27025).

10. In titrimetric analysis, the mass concentration of the solution titiraupenga-defined element set in the three batches or aliquote parts of the original substance. The arithmetic average of the three obtained results are rounded to four significant digits.

The mass concentration of a standard solution prepared from metal or chemical substances establish not less than three batches of the starting material.

Allowed to set, the mass concentration of standard solutions for standard samples, if available in the standard methods for the determination of the item.

11. Weighting the sample the sample, precipitation of metals and chemicals for preparing standard solutions is carried out on the laboratory scales General purpose according to GOST 24104* 2nd accuracy class with the largest weighing limit of 200 g or on any other scales that meets the specified requirements. In standard methods of analysis provide scales with different weighing precision batches, floodplains, their mixtures, indicators and other substances.
________________
* From 1 July 2002 was put into effect GOST 24104−2001.

12. When using instrumental methods of analysis it is necessary to choose optimal conditions of measurement of the analytical signal provides the necessary sensitivity and accuracy depending on the method applied, the type of instrument, of the element and its mass fraction in the sample.

13. Calibration curve building in the system of rectangular coordinates:

the abscissa shows the delay numeric value of the mass concentration, mass fraction or mass of an element in a specific volume of solution;

axis of ordinates the value of the analytical signal, measured parameter or function from it.

Conditions of preparation of solutions for measuring the analytical signal and the method of constructing the calibration graph indicate the standard methods of determining the mass fraction of the element. Validation of calibration curve performed simultaneously with analysis in accordance with the requirements of the standard on methods of determining the mass fraction of the element. Allowed to apply the calibration function representing the equation of the calibration curve, and use the comparison method of the analytical signal of the sample with the analytical signal of standard solution of the element or of the solution of a standard sample, if it is stipulated in standard methods for the determination of the mass fraction of the element.

14. The calibration of automatic analysers carried out according to standard samples and synthetic mixtures that mimic the composition of the analyzed material, or by standard solutions in accordance with the instructions of standard methods of analysis.

15. Mass fraction of the element in the sample and the standard sample determined in two parallel batches.

When the divergence of parallel measurements above the permissible values regulated by the method of analysis, the analysis of the sample is carried out in three parallel batches.

Simultaneously with the analysis under the same conditions conduct control expertise to make the relevant amendment in the result analysis.

Allowed when executing short tests when using the same reagents under the same conditions carried out not less than once per shift control experience for inclusion in the analysis result of the relevant amendment.

A number of control experiments must match the number of parallel definitions in the analysis sample.

16. To control the error of the results of the analysis of the test sample at least once per shift under the same conditions analyze the standard sample in two (three) batches. For control choose a standard sample with a chemical composition corresponding to the requirements of standard methods of analysis of this element.

17. For the result of the analysis of the sample or the standard sample and take the arithmetic average of the two (three) of parallel measurements taking into account the average of the two (three) parallel the results of the control (blank) experience.

18. The error analysis result (at p = 0.95) will not exceed the limit (annexes 1, 2) are given in the relevant standard methods of analysis under the following conditions:

18.1. The difference between the two (three) of parallel definitions should not exceed (at p = 0.95) value () (application 1, 2) are given in the relevant standard methods of analysis. The discrepancy between the results of three parallel measurements is the difference between the highest and lowest values of parallel measurements.

18.2. Played in the standard sample, the value of the mass fraction of the element must not vary from certified more than acceptable (at a confidence level of 0.85) value (appendices 1, 2) are given in the relevant standard methods of analysis.

18.3. If any of the above conditions hold and repeat. If and when re-analysis of the requirements for the accuracy of the results is not met, the results of the analysis to recognize the unfaithful, the analysis is stopped until the identification and elimination of the causes of the disruption of the analysis.

18.4. The difference between the two average results of analysis, obtained under different conditions (for example, when the control intralaboratory reproducibility) shall not exceed (at p = 0.95) values (annexes 1, 2) are given in the relevant standard methods of analysis.

19. The numerical value of the result of the analysis must end with the same number of discharges, and the corresponding error value .

20. In the absence of the standard sample and the control error of the result of the analysis is carried out by additives or the analysis of synthetic mixtures.

21. Monitoring the error of the result of the analysis by the method of additions is carried out by finding the mass fraction of the element in the analyzed material after adding an appropriate sample of pure metal or aliquote part of a standard solution of this component to the sample of analyte prior to analysis. The amount of additives is chosen so to keep the optimum conditions of analysis. Carry out the determination of this element in the sample after the introduction of additives. The amount of additives is chosen so to keep the optimum conditions of analysis provided by a particular standard methods of analysis. Carry out the determination of this element in the sample after the introduction of additives. The amount of additive is calculated as the difference between the found value of the mass fraction of the element in the sample with the additive and without the additive.

The error of the result of the analysis will not exceed the limit , if the sample and the sample with the addition of the conditions in clause 18.1, and also, if the found value differs from the calculated Supplement, no more than , where and are taken from the appropriate standard methods of analysis for values of the mass fraction of the controlled element in a sample and the sample with the additive.

22. Monitoring the error of the result of the analysis of synthetic mixtures is performed by reproducing the values of the mass fraction of the element, is introduced into this mixture. Determination of the mass fraction of the controlled element in the synthetic compound is carried out simultaneously with the analysis of samples with the same number of parallel definitions prescribed by the method of analysis.

The error of the result of the analysis will not exceed limit if for a synthetic mixture of the condition in clause 18.1, and if the reproduced value of the mass fraction of the element in the synthetic compound differs from that introduced into the mixture is not more than the amount taken from the appropriate standard methods of analysis.

ANNEX 1
Reference

ANNEX 2 (informative). THE FORMULAS FOR CALCULATING NORMS AND STANDARDS FOR MONITORING THE ACCURACY OF RESULTS OF QUANTITATIVE CHEMICAL ANALYSIS (KHA)

ANNEX 2
Reference

1. =2,2(confidence probability of 0.95)

2. =2,3(confidence probability of 0.95)

3. =2,8(confidence probability of 0.95)

4. =1,44(confidence probability of 0.95)

5. =2,77(confidence probability of 0.95)

where  — normalized value of the mean square random error of the results KHA characterizing the reproducibility of the results.


The text of the document is verified by:
the official publication of the
Cast iron. Brand. Specifications.
Methods of analysis: Sat. Standards. -
M.: IPK Publishing house of standards, 2004