Technical specifications for development of environmental reference materials
Some standard content:
Technical Specifications for the Development and Reproduction of Environmental Standard Samples
(HJ/T173-20052005-07-01 implementation) (Note: subject to the official version published by China Environmental Science Press) This technical specification is formulated to improve the quality of the development and reproduction of environmental standard samples and ensure the accuracy and reliability of the values of environmental standard samples.
This specification is mainly based on the GB/T15000 "Guidelines for Standard Sample Work" series of standards and the latest technical guidelines for standard samples released by ISC/REMCO, combined with the technical characteristics of the development and reproduction of environmental standard samples, and contains the following five parts: scope, normative reference documents, definitions, organization and management requirements, and technical requirements. The definition part defines environmental standard samples and national environmental standard samples; the organization and management requirements part describes the qualification and qualification requirements of environmental standard sample research and replication institutions, the project establishment, review and approval of national environmental standard sample research and replication plans, and other management procedures; the technical requirements part stipulates the research methods, preparation methods and measurement methods involved in the process of environmental standard sample research and replication. This specification is proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. The drafting unit of this specification is: Standard Sample Research Institute of the State Environmental Protection Administration. This specification was approved by the State Environmental Protection Administration on March 24, 2005. This specification is the first release and will be implemented from July 1, 2005. This specification is interpreted by the State Environmental Protection Administration. 1 Scope
Technical Specification for Research and Reproduction of Environmental Standard Samples
This specification specifies the basic technical requirements for the process of planning, uniformity and stability research and inspection, measurement, characteristic value evaluation, certificate and label production, packaging, storage and transportation of environmental standard samples, and is mainly applicable to the research and replication of environmental standard samples and their technical management. 2 Normative references
The clauses in the following documents become clauses of this specification through reference in this specification. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this specification. However, parties to an agreement based on this specification are encouraged to investigate whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this specification.
GB/T15000.1-1994 Working Guidelines for Standard Samples (1) General provisions for stating standard samples in technical standards
GB/T15000.2-1994 Working Guidelines for Standard Samples (2) Common terms and definitions for standard samples
GB/T15000.3-1994 Working Guidelines for Standard Samples (3) General principles and statistical methods for determining the value of standard samples
GB/T15000.4-2003 Working Guidelines for Standard Samples (4) Contents of the certificate and label of standard samples
GB/T15000.5-1994 Working Guidelines for Standard Samples (5) Technical general rules for chemical composition standard samples
GB/T15000.6-1996 Working Guidelines for Standard Samples (6) General rules for packaging of standard samples
GB/T15000.7-2001 Working Guidelines for Standard Samples (7) General requirements for the capabilities of standard sample producers
GB/T15000.8-2003 Working Guidelines for Standard Samples (8 ) Use of certified standard samples GB/T 4882-1985 Statistical processing and interpretation of data Normality test GB/T 8170-1987 Numerical rounding rules
JJF 1059-1999 Evaluation and expression of uncertainty in measurement 3 Definitions
3.1 Environmental standard samples environmental reference materials are environmental samples or materials that are sufficiently uniform and have fully determined characteristic values, have passed technical review and are accompanied by a certificate of use. They are mainly used to calibrate and verify environmental monitoring and analysis instruments, evaluate and verify environmental monitoring and analysis methods, or determine the characteristic values of other environmental samples. Note: Environmental standard samples prepared with pure chemical reagents (including pure gases) as raw materials are usually called artificially synthesized environmental standard samples, such as standard solutions, standard gases, simulated water quality standard samples for environmental monitoring and analysis; environmental standard samples prepared with actual environmental samples as raw materials are called natural matrix environmental standard samples, such as soil standard samples, air particulate matter standard samples, etc. 3.2 National certified environmental reference materials
Environmental standard samples that have passed the expert technical review organized by the national environmental protection department, approved, issued, authorized for production by the national standardization department and accompanied by a national standard sample certificate, one or more characteristic values are determined by establishing a traceable procedure that can accurately reproduce the measurement unit representing its characteristic value, and are accompanied by a specified confidence level of uncertainty. All national environmental standard samples are national measurement standards for environmental pollutant monitoring and analysis. 4 Organization and management requirements
4.1 Organization requirements
4.1.1 The research and replication unit should have a clear legal status and obtain permission or authorization from the national competent department to carry out the research and replication of environmental standard samples. 4.1.2 The research and replication unit should have the necessary workplace, measuring instruments and equipment, management and professional and technical personnel to carry out the research and replication of environmental standard samples, as well as a quality management system established in accordance with Article 4.1 of GB/T15000.7, and obtain the qualification recognition of standard sample producers based on the requirements of GB/T15000.7.
4.1.3 The research and replication unit shall carry out the research and replication of environmental standard samples in accordance with the technical requirements of this specification, and shall be fully responsible for the quality and technical indicators of the environmental standard samples it has developed and replicated.
4.2 Management requirements
4.2.1 The national administrative department of standardization is the unified management unit for national standard samples, and shall uniformly manage the preparation, implementation, review, approval, release and use supervision of the national standard sample research and replication plan.
4.2.2 The national administrative department of environmental protection is the technical management unit for national environmental standard samples, and shall specifically organize the preparation, implementation and review of the national environmental standard sample research and replication plan. 4.2.3 The research and replication unit shall organize the research and replication of environmental standard samples in accordance with the national environmental standard sample research and replication plan.
5 Technical requirements
5.1 Research and replication planning
5.1.1 Preparation work before research and replication
5.1.1.1 The research and replication unit shall prepare a project proposal for the research and replication plan of environmental standard samples according to the actual needs of the national environmental protection standardization work, and submit the project proposal to the national environmental protection administrative department and the National Standard Sample Technical Committee through the Environmental Standard Sample Sub-Technical Committee of the National Standard Sample Technical Committee for filing and review. 5.1.1.2 The research and replication unit shall determine the research and replication technical route and the level of uncertainty of characteristic values according to the intended use of environmental standard samples. 5.1.1.3 The research and replication unit shall conduct sufficient research and technical demonstration on the containers used to fill environmental standard samples to ensure that the filling containers meet the relevant provisions of GB/T15000.6. 5.1.2 Selection of preparation method
5.1.2.1 The selection of the preparation method of environmental standard samples shall be determined based on existing technical conditions and intended use.
5.1.2.2 Most environmental standard samples are prepared by batch method, i.e., a batch of environmental standard samples with the same characteristic value are prepared at one time, such as common water quality standard samples, soil standard samples, sediment standard samples, biological standard samples, standard solutions, etc. 5.1.2.3 Environmental standard samples can also be prepared by single-piece method, i.e., only one standard sample is prepared at a time, such as bottled standard gas, etc. 5.1.3 Preparation of synthetic environmental standard samples 5.1.3.1 Chemical reagents used to prepare synthetic environmental standard samples should be analyzed and confirmed for purity and major impurities using proven reliable analytical methods before use 5.1.3.2 Environmental standard samples (such as standard solutions, standard gases, permeation tubes, etc.) for calibration of environmental monitoring and analytical instruments are generally accurately prepared by research and replication units using chemical reagents of known purity and weighing instruments and measuring instruments that have been verified by the state, and their characteristic values are evaluated based on the data independently measured by the research and replication units.
5.1.3.3 Environmental standard samples (such as water quality standard samples, etc.) used for environmental monitoring method validation and laboratory quality management are generally accurately prepared by the research and replication unit based on the environmental background value or the need to implement environmental management standards, using chemical reagents of known purity and weighing instruments and measuring instruments that have been calibrated by the state, and their characteristic values are evaluated based on the data jointly measured by multiple qualified laboratories.
5.1.4 Preparation of natural matrix environmental standard samples 5.1.4.1 The collection of natural matrix environmental standard samples should fully consider their intended use to ensure the representativeness of the sampling. Sometimes, in order to prepare natural matrix environmental standard samples containing specific pollutants, this can be achieved by quantitatively adding self-standard pollutants to actual environmental samples 5.1.4.2 The preparation of natural matrix environmental standard samples should select reasonable preparation procedures and processing technology according to actual conditions. During the preparation process, attention should be paid to preventing contamination by foreign objects, avoiding the influence of processing equipment and instruments on the value of the characteristic to be determined, and ensuring that the final natural matrix environmental standard samples have sufficient uniformity and stability. 5.1.4.3 The characteristic value of natural matrix environmental standard samples is generally evaluated based on the data jointly measured by multiple qualified laboratories. 5.2 Uniformity Study and Inspection
5.2.1 Uniformity Study
5.2.1.1 For environmental standard samples prepared by batch method, the uniformity of characteristic value between bottles and within bottles should be studied separately.
5.2.1.2 For environmental standard samples prepared by single-piece method, the uniformity of characteristic value within the bottle should be studied mainly.
5.2.1.3 The study of uniformity between bottles is mainly to determine the variability of characteristic value between the minimum packaging units of the same batch of environmental standard samples. The variance analysis experimental design with equal number of repeated measurements can be adopted, that is, each unit sample is randomly selected and repeated measurements are performed with equal number of times. Through the study of uniformity between bottles, the uncertainty of characteristic quantity values that may be caused by non-uniformity between bottles can be estimated. 5.2.1.4 The study of uniformity within the bottle is mainly to determine the variability of the characteristic quantity values within a single packaging unit of the environmental standard sample. The variance analysis experimental design with equal repeated measurements can also be adopted, that is, the sample in the bottle is first divided into multiple sub-samples, and then each sub-sample is measured repeatedly the same number of times. Through the study of uniformity within the bottle, the minimum sampling volume of the environmental standard sample can be estimated. 5.2.2 Uniformity test
5.2.2.1 The uniformity test is generally carried out by random sampling. The number of samples depends on the total number of units of the environmental standard sample produced and the degree of understanding of the uniformity of the environmental standard sample. When the total number of units of the environmental standard sample produced is less than or equal to 1000, the number of random samples is generally 10 to 20, but not less than 10; when the total number of units of the environmental standard sample produced is greater than 1000, the number of random samples should be no less than 2× (N is the total number of units). 5.2.2.2 For uniformity test, it is advisable to use analytical methods with small repeatability standard deviation and sufficient sensitivity to test characteristic values. 5.2.2.3 For uniformity test, the test order of sample sampling should be randomized as much as possible, and the test should be completed under the same experimental conditions and instrument status as much as possible. For environmental standard samples with multiple characteristic values, representative and non-uniform characteristics can be selected for uniformity test. 5.2.2.4 For uniformity test, the F test method is generally used, that is, to compare whether there is a statistically significant difference between the measurement variance within the bottle and the variance of the analytical method, and between the measurement variance between bottles and the measurement variance within the bottle. When the uncertainty of the non-uniformity of the tested characteristic is negligible compared with the uncertainty of the analytical method used, the uniformity of the environmental standard sample can be considered good; when the uncertainty of the non-uniformity of the tested characteristic is significantly greater than the uncertainty of the analytical method and is the main source of the expected uncertainty of the characteristic value, the environmental standard sample can be considered non-uniform; when the uncertainty of the non-uniformity of the tested characteristic is similar to the uncertainty of the analytical method and is not negligible compared with the expected self-standard uncertainty of the characteristic value, the uncertainty of the non-uniformity should be considered in the combined uncertainty of the environmental standard sample. 5.3 Stability Study and Inspection
5.3.1 Stability Study
5.3.1.1 The stability study of environmental standard samples is mainly to find various measures and methods to ensure the stable preservation of their characteristic values, and to analyze the trend of the variability of the characteristic values that may be caused by the changes of environmental standard samples over time under the specified storage and transportation conditions. The best stability measures and methods should meet the actual work needs of environmental standard samples for easy long-term storage and convenient transportation as much as possible.
5.3.1.2 Long-term stability research is mainly conducted by observing the changing trend of characteristic quantity values of environmental standard samples under given storage conditions (such as temperature, humidity, pressure, light, etc.) with storage time. The characteristic quantity values of most environmental standard samples change very slowly during long-term storage, and the changing trend can be studied by a simple linear fitting model; however, the characteristic quantity values of some environmental standard samples will change significantly over time, and their changing laws have been confirmed, such as the radioactive decay of substances. Through long-term stability research, the uncertainty of the quantity values of environmental standard samples that may be caused by long-term storage and the life of environmental standard samples can be estimated. 5.3.1.3 Short-term stability research is mainly conducted by observing the changing trend of characteristic quantity values of environmental standard samples under actual transportation conditions in a short period of time. When the characteristic quantity values of environmental standard samples change significantly during transportation, efforts should be made to improve the preparation method or transportation conditions of environmental standard samples.
5.3.2 Stability test
5.3.2.1 Stability test It is advisable to use an analytical method with a small reproducibility standard deviation and sufficient sensitivity to detect the characteristic quantity values. 5.3.2.2 The stability test should be completed under the same experimental conditions as much as possible. For environmental standard samples with multiple characteristic values, representative and easily changeable characteristics can be selected for stability test.
5.3.2.3 If the stability test data of environmental standard samples obtained in chronological order fluctuate within the uncertainty range of the analytical method and there is no significant directional change, the environmental standard sample can be considered stable during the test period. 5.3.2.4 The stability test data is the basic basis for determining the validity period of environmental standard samples. The validity period of national environmental standard samples should be at least one year. All environmental standard samples must be marked with the validity period, and environmental standard samples that have exceeded the validity period shall be re-tested and confirmed before the validity period can be extended.
5.4 Determination
5.4.1 Traceability of measurement value
The traceability of the characteristic measurement value of environmental standard samples can be obtained either through a continuous comparison chain or by applying a proven reliable analytical method. The traceability of environmental standard samples characterized by physical properties is generally linked to SI units or their derived units through step-by-step calibration of measuring instruments: The traceability of environmental standard samples characterized by chemical composition properties is mainly through accurate measurement of characteristic quantity values by proven reliable analytical methods. National environmental standard samples should explain the principles and methods on which their characteristic quantity values are obtained. 5.4.2 Determination method
The determination of environmental standard samples can be carried out in one of the following three ways according to the type of sample, intended use, etc.:
5.4.2.1 The research and replication unit adopts an internationally recognized benchmark analytical method (such as isotope dilution mass spectrometry, coulometric method, gravimetric method, titration method and freezing point depression method) for determination. The environmental standard samples determined by this method mainly include standard gases, standard solutions and standard samples with characteristic quantity values expressed in purity.
5.4.2.2 The research and replication unit (which contains multiple independent laboratories) adopts two or more analytical methods with different principles and proven reliability for determination. These analytical methods should have a small measurement uncertainty for the intended use of environmental standard samples; environmental standard samples measured by this method mainly include standard gases, standard solutions and standard samples whose characteristic values are expressed in purity that are difficult to measure using benchmark analytical methods. 5.4.2.3 The research and replication unit shall organize multiple qualified laboratories to use one or more analytical methods that have been proven to be reliable for measurement. Environmental standard samples measured by this method are mainly various environmental matrix standard samples.
5.4.3 Basic requirements for measurement data4 The purpose of the in-bottle uniformity study is to determine the variability of the characteristic quantity value in a single packaging unit of the environmental standard sample. The variance analysis experimental design with equal repeated measurements can also be used, that is, the sample in the bottle is first divided into multiple sub-samples, and then each sub-sample is measured repeatedly the same number of times. The minimum sampling volume of the environmental standard sample can be estimated through the in-bottle uniformity study. 5.2.2 Uniformity test
5.2.2.1 The uniformity test is generally carried out by random sampling. The number of samples depends on the total number of units of the environmental standard sample produced and the degree of understanding of the uniformity of the environmental standard sample. When the total number of units of the environmental standard sample produced is less than or equal to 1000, the number of random samples is generally 10 to 20, but not less than 10; when the total number of units of the environmental standard sample produced is greater than 1000, the number of random samples should be no less than 2× (N is the total number of units). 5.2.2.2 The uniformity test should use an analytical method with a small repeatability standard deviation and sufficient sensitivity to detect the characteristic quantity value. 5.2.2.3 The uniformity test should make the inspection order of the sample randomized as much as possible, and be completed under the same experimental conditions and instrument status as much as possible. Environmental standard samples with multiple characteristic values can select representative and difficult to be uniform characteristics for uniformity test. 5.2.2.4 The uniformity test is generally carried out by F test method, that is, comparing whether there is a statistically significant difference between the measurement variance within the bottle and the variance of the analysis method, and between the measurement variance between bottles and the measurement variance within the bottle. When the uncertainty of the non-uniformity of the tested characteristic is negligible compared with the uncertainty of the analytical method used, the uniformity of the environmental standard sample can be considered good; when the uncertainty of the non-uniformity of the tested characteristic is significantly greater than the uncertainty of the analytical method and is the main source of the expected uncertainty of the characteristic value, the environmental standard sample can be considered non-uniform; when the uncertainty of the non-uniformity of the tested characteristic is similar to the uncertainty of the analytical method and is not negligible compared with the expected self-standard uncertainty of the characteristic value, the uncertainty of the non-uniformity should be considered in the combined uncertainty of the environmental standard sample. 5.3 Stability Study and Inspection
5.3.1 Stability Study
5.3.1.1 The stability study of environmental standard samples is mainly to find various measures and methods to ensure the stable preservation of their characteristic values, and to analyze the trend of the variability of the characteristic values that may be caused by the changes of environmental standard samples over time under the specified storage and transportation conditions. The best stability measures and methods should meet the actual work needs of environmental standard samples for easy long-term storage and convenient transportation as much as possible.
5.3.1.2 Long-term stability research is mainly conducted by observing the changing trend of characteristic quantity values of environmental standard samples under given storage conditions (such as temperature, humidity, pressure, light, etc.) with storage time. The characteristic quantity values of most environmental standard samples change very slowly during long-term storage, and the changing trend can be studied by a simple linear fitting model; however, the characteristic quantity values of some environmental standard samples will change significantly over time, and their changing laws have been confirmed, such as the radioactive decay of substances. Through long-term stability research, the uncertainty of the quantity values of environmental standard samples that may be caused by long-term storage and the life of environmental standard samples can be estimated. 5.3.1.3 Short-term stability research is mainly conducted by observing the changing trend of characteristic quantity values of environmental standard samples under actual transportation conditions in a short period of time. When the characteristic quantity values of environmental standard samples change significantly during transportation, efforts should be made to improve the preparation method or transportation conditions of environmental standard samples.
5.3.2 Stability test
5.3.2.1 Stability test It is advisable to use an analytical method with a small reproducibility standard deviation and sufficient sensitivity to detect the characteristic quantity values. 5.3.2.2 The stability test should be completed under the same experimental conditions as much as possible. For environmental standard samples with multiple characteristic values, representative and easily changeable characteristics can be selected for stability test. wwW.bzxz.Net
5.3.2.3 If the stability test data of environmental standard samples obtained in chronological order fluctuate within the uncertainty range of the analytical method and there is no significant directional change, the environmental standard sample can be considered stable during the test period. 5.3.2.4 The stability test data is the basic basis for determining the validity period of environmental standard samples. The validity period of national environmental standard samples should be at least one year. All environmental standard samples must be marked with the validity period, and environmental standard samples that have exceeded the validity period shall be re-tested and confirmed before the validity period can be extended.
5.4 Determination
5.4.1 Traceability of measurement value
The traceability of the characteristic measurement value of environmental standard samples can be obtained either through a continuous comparison chain or by applying a proven reliable analytical method. The traceability of environmental standard samples characterized by physical properties is generally linked to SI units or their derived units through step-by-step calibration of measuring instruments: The traceability of environmental standard samples characterized by chemical composition properties is mainly through accurate measurement of characteristic quantity values by proven reliable analytical methods. National environmental standard samples should explain the principles and methods on which their characteristic quantity values are obtained. 5.4.2 Determination method
The determination of environmental standard samples can be carried out in one of the following three ways according to the type of sample, intended use, etc.:
5.4.2.1 The research and replication unit adopts an internationally recognized benchmark analytical method (such as isotope dilution mass spectrometry, coulometric method, gravimetric method, titration method and freezing point depression method) for determination. The environmental standard samples determined by this method mainly include standard gases, standard solutions and standard samples with characteristic quantity values expressed in purity.
5.4.2.2 The research and replication unit (which contains multiple independent laboratories) adopts two or more analytical methods with different principles and proven reliability for determination. These analytical methods should have a small measurement uncertainty for the intended use of environmental standard samples; environmental standard samples measured by this method mainly include standard gases, standard solutions and standard samples whose characteristic values are expressed in purity that are difficult to measure using benchmark analytical methods. 5.4.2.3 The research and replication unit shall organize multiple qualified laboratories to use one or more analytical methods that have been proven to be reliable for measurement. Environmental standard samples measured by this method are mainly various environmental matrix standard samples.
5.4.3 Basic requirements for measurement data4 The purpose of the in-bottle uniformity study is to determine the variability of the characteristic quantity value in a single packaging unit of the environmental standard sample. The variance analysis experimental design with equal repeated measurements can also be used, that is, the sample in the bottle is first divided into multiple sub-samples, and then each sub-sample is measured repeatedly the same number of times. The minimum sampling volume of the environmental standard sample can be estimated through the in-bottle uniformity study. 5.2.2 Uniformity test
5.2.2.1 The uniformity test is generally carried out by random sampling. The number of samples depends on the total number of units of the environmental standard sample produced and the degree of understanding of the uniformity of the environmental standard sample. When the total number of units of the environmental standard sample produced is less than or equal to 1000, the number of random samples is generally 10 to 20, but not less than 10; when the total number of units of the environmental standard sample produced is greater than 1000, the number of random samples should be no less than 2× (N is the total number of units). 5.2.2.2 The uniformity test should use an analytical method with a small repeatability standard deviation and sufficient sensitivity to detect the characteristic quantity value. 5.2.2.3 The uniformity test should make the inspection order of the sample randomized as much as possible, and be completed under the same experimental conditions and instrument status as much as possible. Environmental standard samples with multiple characteristic values can select representative and difficult to be uniform characteristics for uniformity test. 5.2.2.4 The uniformity test is generally carried out by F test method, that is, comparing whether there is a statistically significant difference between the measurement variance within the bottle and the variance of the analysis method, and between the measurement variance between bottles and the measurement variance within the bottle. When the uncertainty of the non-uniformity of the tested characteristic is negligible compared with the uncertainty of the analytical method used, the uniformity of the environmental standard sample can be considered good; when the uncertainty of the non-uniformity of the tested characteristic is significantly greater than the uncertainty of the analytical method and is the main source of the expected uncertainty of the characteristic value, the environmental standard sample can be considered non-uniform; when the uncertainty of the non-uniformity of the tested characteristic is similar to the uncertainty of the analytical method and is not negligible compared with the expected self-standard uncertainty of the characteristic value, the uncertainty of the non-uniformity should be considered in the combined uncertainty of the environmental standard sample. 5.3 Stability Study and Inspection
5.3.1 Stability Study
5.3.1.1 The stability study of environmental standard samples is mainly to find various measures and methods to ensure the stable preservation of their characteristic values, and to analyze the trend of the variability of the characteristic values that may be caused by the changes of environmental standard samples over time under the specified storage and transportation conditions. The best stability measures and methods should meet the actual work needs of environmental standard samples for easy long-term storage and convenient transportation as much as possible.
5.3.1.2 Long-term stability research is mainly conducted by observing the changing trend of characteristic quantity values of environmental standard samples under given storage conditions (such as temperature, humidity, pressure, light, etc.) with storage time. The characteristic quantity values of most environmental standard samples change very slowly during long-term storage, and the changing trend can be studied by a simple linear fitting model; however, the characteristic quantity values of some environmental standard samples will change significantly over time, and their changing laws have been confirmed, such as the radioactive decay of substances. Through long-term stability research, the uncertainty of the quantity values of environmental standard samples that may be caused by long-term storage and the life of environmental standard samples can be estimated. 5.3.1.3 Short-term stability research is mainly conducted by observing the changing trend of characteristic quantity values of environmental standard samples under actual transportation conditions in a short period of time. When the characteristic quantity values of environmental standard samples change significantly during transportation, efforts should be made to improve the preparation method or transportation conditions of environmental standard samples.
5.3.2 Stability test
5.3.2.1 Stability test It is advisable to use an analytical method with a small reproducibility standard deviation and sufficient sensitivity to detect the characteristic quantity values. 5.3.2.2 The stability test should be completed under the same experimental conditions as much as possible. For environmental standard samples with multiple characteristic values, representative and easily changeable characteristics can be selected for stability test.
5.3.2.3 If the stability test data of environmental standard samples obtained in chronological order fluctuate within the uncertainty range of the analytical method and there is no significant directional change, the environmental standard sample can be considered stable during the test period. 5.3.2.4 The stability test data is the basic basis for determining the validity period of environmental standard samples. The validity period of national environmental standard samples should be at least one year. All environmental standard samples must be marked with the validity period, and environmental standard samples that have exceeded the validity period shall be re-tested and confirmed before the validity period can be extended.
5.4 Determination
5.4.1 Traceability of measurement value
The traceability of the characteristic measurement value of environmental standard samples can be obtained either through a continuous comparison chain or by applying a proven reliable analytical method. The traceability of environmental standard samples characterized by physical properties is generally linked to SI units or their derived units through step-by-step calibration of measuring instruments: The traceability of environmental standard samples characterized by chemical composition properties is mainly through accurate measurement of characteristic quantity values by proven reliable analytical methods. National environmental standard samples should explain the principles and methods on which their characteristic quantity values are obtained. 5.4.2 Determination method
The determination of environmental standard samples can be carried out in one of the following three ways according to the type of sample, intended use, etc.:
5.4.2.1 The research and replication unit adopts an internationally recognized benchmark analytical method (such as isotope dilution mass spectrometry, coulometric method, gravimetric method, titration method and freezing point depression method) for determination. The environmental standard samples determined by this method mainly include standard gases, standard solutions and standard samples with characteristic quantity values expressed in purity.
5.4.2.2 The research and replication unit (which contains multiple independent laboratories) adopts two or more analytical methods with different principles and proven reliability for determination. These analytical methods should have a small measurement uncertainty for the intended use of environmental standard samples; environmental standard samples measured by this method mainly include standard gases, standard solutions and standard samples whose characteristic values are expressed in purity that are difficult to measure using benchmark analytical methods. 5.4.2.3 The research and replication unit shall organize multiple qualified laboratories to use one or more analytical methods that have been proven to be reliable for measurement. Environmental standard samples measured by this method are mainly various environmental matrix standard samples.
5.4.3 Basic requirements for measurement data2 Long-term stability studies are mainly conducted by observing the changing trends of characteristic values of environmental standard samples under given storage conditions (such as temperature, humidity, pressure, light, etc.) with storage time. The characteristic values of most environmental standard samples change very slowly during long-term storage, and the changing trends can be studied through simple linear fitting models; however, the characteristic values of some environmental standard samples will change significantly over time, and their changing laws have been confirmed, such as the radioactive decay of substances. Through long-term stability studies, the uncertainty of the values of environmental standard samples caused by long-term storage and the life of environmental standard samples can be estimated. 5.3.1.3 Short-term stability studies are mainly conducted by observing the changing trends of characteristic values of environmental standard samples under actual transportation conditions in a short period of time. When the characteristic values of environmental standard samples change significantly during transportation, efforts should be made to improve the preparation method or transportation conditions of environmental standard samples.
5.3.2 Stability test
5.3.2.1 Stability test It is advisable to use analytical methods with small reproducibility standard deviation and sufficient sensitivity to detect characteristic values. 5.3.2.2 Stability tests should be completed under the same experimental conditions as much as possible. Environmental standard samples with multiple characteristic values can select representative and easily changeable characteristics for stability testing.
5.3.2.3 If the stability test data of environmental standard samples obtained in chronological order fluctuate within the uncertainty range of the analytical method and there is no significant directional change, the environmental standard sample can be considered stable during the test period. 5.3.2.4 The stability test data is the basic basis for determining the validity period of environmental standard samples. The validity period of national environmental standard samples should be at least one year. All environmental standard samples must be marked with the validity period, and environmental standard samples that have exceeded the validity period shall be re-tested and confirmed before the validity period can be extended.
5.4 Determination
5.4.1 Traceability of measurement values
The traceability of the characteristic measurement values of environmental standard samples can be obtained either through a continuous comparison chain or by applying a proven reliable analytical method. The traceability of environmental standard samples characterized by physical properties is generally linked to SI units or their derived units through step-by-step calibration of measuring instruments: The traceability of environmental standard samples characterized by chemical composition properties is mainly through accurate measurement of characteristic quantity values by proven reliable analytical methods. National environmental standard samples should explain the principles and methods on which their characteristic quantity values are obtained. 5.4.2 Determination method
The determination of environmental standard samples can be carried out in one of the following three ways according to the type of sample, intended use, etc.:
5.4.2.1 The research and replication unit adopts an internationally recognized benchmark analytical method (such as isotope dilution mass spectrometry, coulometric method, gravimetric method, titration method and freezing point depression method) for determination. The environmental standard samples determined by this method mainly include standard gases, standard solutions and standard samples with characteristic quantity values expressed in purity.
5.4.2.2 The research and replication unit (which contains multiple independent laboratories) adopts two or more analytical methods with different principles and proven reliability for determination. These analytical methods should have a small measurement uncertainty for the intended use of environmental standard samples; environmental standard samples measured by this method mainly include standard gases, standard solutions and standard samples whose characteristic values are expressed in purity that are difficult to measure using benchmark analytical methods. 5.4.2.3 The research and replication unit shall organize multiple qualified laboratories to use one or more analytical methods that have been proven to be reliable for measurement. Environmental standard samples measured by this method are mainly various environmental matrix standard samples.
5.4.3 Basic requirements for measurement data2 Long-term stability studies are mainly conducted by observing the changing trends of characteristic values of environmental standard samples under given storage conditions (such as temperature, humidity, pressure, light, etc.) with storage time. The characteristic values of most environmental standard samples change very slowly during long-term storage, and the changing trends can be studied through simple linear fitting models; however, the characteristic values of some environmental standard samples will change significantly over time, and their changing laws have been confirmed, such as the radioactive decay of substances. Through long-term stability studies, the uncertainty of the values of environmental standard samples caused by long-term storage and the life of environmental standard samples can be estimated. 5.3.1.3 Short-term stability studies are mainly conducted by observing the changing trends of characteristic values of environmental standard samples under actual transportation conditions in a short period of time. When the characteristic values of environmental standard samples change significantly during transportation, efforts should be made to improve the preparation method or transportation conditions of environmental standard samples.
5.3.2 Stability test
5.3.2.1 Stability test It is advisable to use analytical methods with small reproducibility standard deviation and sufficient sensitivity to detect characteristic values. 5.3.2.2 Stability tests should be completed under the same experimental conditions as much as possible. Environmental standard samples with multiple characteristic values can select representative and easily changeable characteristics for stability testing.
5.3.2.3 If the stability test data of environmental standard samples obtained in chronological order fluctuate within the uncertainty range of the analytical method and there is no significant directional change, the environmental standard sample can be considered stable during the test period. 5.3.2.4 The stability test data is the basic basis for determining the validity period of environmental standard samples. The validity period of national environmental standard samples should be at least one year. All environmental standard samples must be marked with the validity period, and environmental standard samples that have exceeded the validity period shall be re-tested and confirmed before the validity period can be extended.
5.4 Determination
5.4.1 Traceability of measurement values
The traceability of the characteristic measurement values of environmental standard samples can be obtained either through a continuous comparison chain or by applying a proven reliable analytical method. The traceability of environmental standard samples characterized by physical properties is generally linked to SI units or their derived units through step-by-step calibration of measuring instruments: The traceability of environmental standard samples characterized by chemical composition properties is mainly through accurate measurement of characteristic quantity values by proven reliable analytical methods. National environmental standard samples should explain the principles and methods on which their characteristic quantity values are obtained. 5.4.2 Determination method
The determination of environmental standard samples can be carried out in one of the following three ways according to the type of sample, intended use, etc.:
5.4.2.1 The research and replication unit adopts an internationally recognized benchmark analytical method (such as isotope dilution mass spectrometry, coulometric method, gravimetric method, titration method and freezing point depression method) for determination. The environmental standard samples determined by this method mainly include standard gases, standard solutions and standard samples with characteristic quantity values expressed in purity.
5.4.2.2 The research and replication unit (which contains multiple independent laboratories) adopts two or more analytical methods with different principles and proven reliability for determination. These analytical methods should have a small measurement uncertainty for the intended use of environmental standard samples; environmental standard samples measured by this method mainly include standard gases, standard solutions and standard samples whose characteristic values are expressed in purity that are difficult to measure using benchmark analytical methods. 5.4.2.3 The research and replication unit shall organize multiple qualified laboratories to use one or more analytical methods that have been proven to be reliable for measurement. Environmental standard samples measured by this method are mainly various environmental matrix standard samples.
5.4.3 Basic requirements for measurement data
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