Geneeral rules for preparation and sampling sample for emission spectrum analysis
Some standard content:
Guiding Technical Documents of the Ministry of Electronics Industry of the People's Republic of China General Rules for the Preparation of Standard Samples for Spectral Analysis
This general rule applies to the preparation of standard samples for mass production and laboratory synthesis. 1 Reference Standards
1.1GB9259-88 Terminology of Emission Spectral Analysis. SJ/Z8206.7—89bZxz.net
1.2SJ/Z3206.14-89 General Rules for Errors in Spectrochemical Analysis and Experimental Data Processing Methods. 2 Definitions and Regulations
2.1 Standard samples (referred to as standard samples) are standard reference materials. That is, materials with accurate composition and good properties and have been identified. They are usually manufactured, measured and identified by standardization organizations recognized by the State Bureau of Technical Supervision or the competent authorities or recognized authoritative units. They are mainly used for calibrating secondary standards, correcting measurement systems and for arbitration analysis, and are also called primary standards. 2.2 Secondary standard samples are standard samples manufactured or synthesized according to the production process and calibrated with primary standards. They are mainly used for daily production management, and are also called control (management) standards. 2.8 Spectral standards A set of standards with different contents, used to draw working curves in spectral analysis and determine the functional relationship between element concentration and spectral line intensity.
2.4 One or more main components in the matrix sample, which can also be the component to be measured. 2.5 Measured component The component whose content in the analyzed object needs to be accurately known, including impurities and certain main components. 2.6 The sum of all other components in the raw material except the component to be measured. When preparing standards, it can be a pure substance, a blank mineral or a multi-element matrix. 3 Types of standards
3.1 Bulk metal and alloy standards, including standards for measuring gases in metals. Mainly used for spectral analysis of metals and alloys.
3.2 Powder standards Standards in the form of powders such as metals, oxides, and salts. Mainly synthesized on a laboratory scale. Used for the analysis of various powdered substances and some metals. 3.3 Solution standards Standards in the form of liquids, used to analyze solution samples. When the non-uniform state and organizational structure of the solid sample seriously affect the analysis results, a solution standard is used. The solid standard can also be calibrated with a solution standard. 3.4 Gas standard A standard in the form of gas. Used for the analysis of gases and gas mixtures. 4 Basic requirements for standards
The standard and the sample to be analyzed should have the same spectral characteristics. That is, under the same conditions, the spectral line intensity emitted by the elements of the same concentration in the standard and the sample should be equal. Approved by the Ministry of Electronics Industry of the People's Republic of China on February 10, 1989 and implemented on March 1, 1989
SJ/Z3206.7-89
4.1 The content of the measured component is sufficiently accurate. The standard includes three components: the matrix (including the multi-element matrix), the measured component, and other components that do not need to be measured or are not suitable for spectral analysis. The content of the measured component is usually expressed as the percentage of the component in the total weight of the sample. It is the average of multiple measurements and represents the true value at a certain confidence level.
4.2 Homogeneous distribution of components The sample consumed by spectral analysis generally does not exceed 1g. The error caused by uneven components is large, so the uniformity of the standard sample needs to be checked. The method is shown in SJ/Z3206.8--89 (Standard Sample or Sample Uniformity Test Method) to meet certain requirements. 4.3 The standard sample and the analytical sample should have similar chemical composition and the same organizational structure. 4.4 The standard sample should have good measurement characteristics. The content range included in the standard sample group should be slightly wider than the range to be measured. A group of standard samples should not be less than 3, and the coordinate points are required to be evenly distributed on the working curve drawn with logarithmic coordinates.
5 Standard sample preparation method
5.1 Standard sample design
5.1.1 List the names of the components to be measured and the actual content range specified in the product technical standards. 5.1.2 Draft the names and content ranges of each component in the standard sample to be prepared. The matrix should remain constant in the standard sample, the content range of the main component to be measured should extend 5 to 30% above and below the specified range, and the maximum content range of the impurity component to be measured should vary within two orders of magnitude. Components that are not suitable for spectral analysis should be added to each standard sample according to the content specified in the product technical standards and remain unchanged. They do not need to be measured for the time being, but it is expected that the impurities that will be required to be measured in the future can be added to the standard sample as the measured components. Other impurities in the standard sample should be kept below a certain maximum content limit. 5.1.3 Determine the number of prepared standard samples and the quality of each standard sample. The minimum number of standard samples is 3, and the best is 5. If the content range to be measured is too wide. Multiple standard samples can be prepared for selection and combination. 51.4 Determine the required content of the guest component in the standard sample. Usually, the 12-5--1 or 1-3-1 method (i.e., the content is 0.1, 0.2, 0.5, 1.0 or 0.1, 0.3, 1.0) is used to make the coordinate points equidistantly distributed in the logarithmic coordinate system.
5.1.5 List the content distribution table, cross-distribute the content of different components in each standard sample, and make the matrix (or the sum of the measured components) in each standard sample roughly equal, and then use it as the final prepared content value. 5.2 Calculation
Before calculation, the method of expressing the content specified in the product standard (element ratio, compound ratio, or ratio of element to compound, etc.) should be clarified. As a calculation method, the following only calculates one measured component. 5.2.1 Direct preparation
Prepare M (g) standard sample containing the measured component content a (%), and the mass of the measured component to be weighed is x (g).
x=Mxa%
The mass of the raw material to be weighed is y (g).
（2）
SJ/Z3206.7-89
When the content of the component in the standard sample is expressed in elements and it is necessary to prepare it in the form of elemental compounds, the mass of the elemental compound to be weighed is x (g) using the following formula. x'=M_×a%
In the formula, m--the molecular weight of the elemental compound
the number of atoms of the element in the five-element compound, the atomic disk of the element A,
the conversion factor of the element to the compound.
The mass of the raw material compound to be weighed is y\ (g). y=(Mx)m
5.2.2 Preparation by dilution
（3）
（4）
When preparing a small amount of powder and solution standard samples for trace element determination, in order to eliminate the difficulties and errors in weighing and measuring, a standard sample with a higher content (main standard) is often prepared first, and then a series of standard samples are made by diluting the raw materials one by one.
From a high-content standard sample with a content of a (%), a low-content standard sample with a content of b (%) is prepared by diluting the mass M (g). The mass of the standard sample with a content of a (%) to be weighed is x (g). b
The mass of the raw material to be weighed is y (g).
5.3 Preparation method
5.3.1 Melting and casting method
(5)
Metal and alloy rod and block standard samples are generally prepared by melting and casting. The calculated raw materials and various ingredients are smelted in a furnace and cast in a mold to obtain a cast state standard sample. The large ingot is processed into a rod or block, or the ingot is forged and rolled to be processed into a standard sample with the same shape and size as the analysis sample. The conditions of the melting and processing method need to be the same as those of the production sample.
5.3.2 Powder synthesis method
In the metal, oxide, and salt powder raw materials, the measured components of the calculation disk are added in a certain way and mixed evenly to form a synthetic standard sample. There are three preparation methods: 5.3.2.1 The measured component is added to the raw material solution in the form of a solution, mixed evenly, evaporated to dryness at an appropriate temperature to become a salt, and then burned at an appropriate temperature to become an oxide. The standard sample prepared by this method has good homogeneity and its existence state is similar to that of the analytical sample.
5.3.2.2 The measured component and the raw material are mixed in powder form. The components of the standard sample are mechanical mixtures and are quite different from the analytical sample. In order to obtain good homogeneity, anhydrous ethanol can be added during grinding and wet grinding is used. 5.3.2.3 The measured component is added to the powder raw material in the form of a solution, slowly evaporated and mixed at an appropriate temperature. SJ/Z3206.7-89
The homogeneity and existence state of the standard sample prepared by this method are between the above two methods. 5.3.3 Solution synthesis method
Dissolve the raw material in an appropriate solvent and maintain a certain concentration. Add the calculated solution of the measured component and mix evenly to form a synthetic solution standard. The solution standard should maintain a certain acidity and be shaken before use. It cannot be stored for a long time. When preparing, avoid using solvents that generate volatile compounds or precipitation with the measured component. 5.4 Factors affecting the quality of standard samples
5.4.1 The purity of raw materials is the main factor affecting the accuracy of the measured components and needs to be checked before use. The measured impurities contained in the raw materials should be 0.5 to 1 order of magnitude lower than the lowest content in the standard sample. The content of the components that do not need to be measured should be the same as the content of the components in the analyzed material. 5.4.2 The purity of the measured components is lower than that of the raw materials, but it must be checked in advance. Special attention should be paid to avoid the situation where the same impurity is contained in multiple measured components. Generally, analytically pure reagents that have been checked can meet the requirements.
5.4.3 The errors caused by weighing and measuring should be reduced to a negligible level. For example, the error caused by weighing 50-100 mg with an analytical balance (accurate to ±0.1 mg) can be ignored. When this requirement cannot be met, it is necessary to prepare a high-content "main standard" and then dilute it with the raw materials to prepare a series of standard samples. 5.4.4 Homogeneity of standard samples In the melting and casting method, smelting process measures that can make the components evenly distributed should be adopted, such as stirring, repeated melting, adding intermediate alloys, etc. In the powder method, the particle size of the powder should be above 120 mesh. Extending the grinding and mixing time, adding anhydrous ethanol to wet grinding when preparing a small amount, and using the solution preparation method can all achieve sufficient homogeneity.
5.4.5 Pollution During the preparation of standard samples, a good clean environment should be maintained to prevent contamination caused by the outside world. The reagents and water used must meet certain purity requirements. Grinding powders should be done with hard grinding tools or grinding tools made of the material being analyzed.
Standard sample uniformity inspection
Perform in accordance with the provisions of SJ/Z3206.9-89.
Note: Standard samples produced in large quantities must undergo uniformity inspection, while general experimental synthetic standards do not need uniformity inspection. 7 Careful determination of standard samples
The standard value of the standard sample is an important parameter of the standard sample. Standard samples produced in large quantities need to be analyzed using accurate chemical analysis methods, preferably standard methods or reliable physical analysis methods, in several laboratories with high technical levels and proficient in the analysis of this material, and the content of the standard sample is determined by multiple measurements by skilled analysts. 7.1 Before analyzing the content of the standard sample, in addition to the uniformity inspection, it is also necessary to check whether the standard sample has the expected concentration gradient to prevent negligent errors in preparation. 7.2 Analyze using standard chemical analysis methods or reliable physical analysis methods, each method shall be performed by more than two analysts.
7.3 The number of analysis units shall not be less than 5.
7.4 The analysis data shall be processed in accordance with the provisions of SJ/Z3206.9-89. 7.5 Obtain the average value of each component to be measured in the standard sample. —4
8 Practical performance assessment of standard samples
SJ/Z3206.7-89
8.1 The standard sample manufacturer shall provide the analysis method, and draw a working curve with the logarithm of the content of the component to be measured in the standard sample and the logarithm of the intensity ratio of the corresponding analysis line pair. Repeat 6 to 10 times, the curve should be a straight line, and the content of the deviating point should be corrected.
8.2 In more than 3 units, use the prepared standard sample to analyze the same type of standard sample other than the standard sample in this batch, or the production sample with reliable data after multiple analysis (in the three content ranges of high, medium and low). The data shall be judged according to the provisions of SJ/Z2306.14-89 (General Rules for Spectrochemical Analysis Errors and Experimental Data Processing Methods). 9 Identification of Standard Samples
The standard sample manufacturer shall provide comprehensive technical information on the preparation, calibration and assessment of the standard sample, and the relevant competent authorities shall preside over the identification and put forward a conclusion on whether the standard sample can be used in actual work, and put it on the market after approval by the competent authorities. Additional Notes:
This standard was proposed by the Electronic Standardization Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the 774th Factory and the Electronic Standardization Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Wang Jinxue, Zhao Changchun and Huang Wenyu. 5
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