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Shanghai Shang Shaft Bearing Quality Inspection Institute Co., Ltd.

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Address: 301 Shangxue Road, Jiading District, Shanghai

How to do method confirmation

2021-01-29 14:35

How to do method confirmation

Preliminary evaluation of non-standard methods


The contents of the preliminary assessment include at least but not limited:


1) Whether the laboratory has the resources to implement the standard (manpower, facilities and environment, instruments and equipment, measurement traceability, etc.);
2) The uncertainty of measurement;
3) Detection limit;
4) recovery rate;
5) selectivity of the method;
6) the concentration range used;
7) Repeatability limit and/or reproducibility limit and precision;
8) robustness against external influences;
9) Cross sensitivity to interference from the sample matrix (sample matrix);
10) Traceability verification;
11) security of the method;
12) the economy of the method.

Non-standard method test confirmation


1) Public Number [Laboratory ISO17025] Reminds: After evaluation, the technical director shall arrange the method confirmation personnel to test and confirm the appropriate method. If necessary, authoritative technical institutions may be invited to assist in technical confirmation.


2) Through the concentration range, sample matrix, interference and elimination, reagents and materials, instruments and equipment, method performance indicators (including calibration curve, measurement range, accuracy, measurement uncertainty of precision results, detection limit, quantitative limit, selectivity, linearity, repeatability or reproducibility of the method, recovery rate, robustness against external influences or interaction sensitivity against interference from sample or test substance matrix and bias, etc.) and other elements to confirm, according to the applicable scope of the method, no less than one actual sample is selected for determination.


3) Use certified standard materials (CRMs) to evaluate method deviations. The certified reference material used shall be consistent with the sample matrix as much as possible. The level of the analyte should also be within the applicable range of the method. Attention shall be paid to the concentration level required by the customer and the detection performance characteristics in the vicinity of the specified limit. If there is no certified standard substance with suitable matrix, the recovery rate should be studied or compared with the standard reference method. During the confirmation process, attention should be paid to the possible phenomena in the test. All test contents and results shall be detailed.


4) After testing and evaluation of uncertainty, a test verification report should be written. Among them, the reporting limit should be set at a certain level of confidence that quantitative results can be obtained, the detection limit and reporting limit can be explained and explained, and the measures to maintain the performance of the method in daily application. These measures should be included in the quality control clause. The report should record in detail the procedures, processes and results of the validation, evaluate whether the method can meet the intended use (statement), and give clear concluding comments.


5) When the equipment and environment changes may affect the test results or do not meet the requirements of the manufacturer, the characteristics of the test method shall be reconfirmed.


6) Review whether the above characteristics obtained in the process of method confirmation meet the customer's technical requirements. Non-standard methods should be approved by not less than 3 experts with senior professional titles and above in this field. If necessary, non-standard methods should also be verified by at least 3 laboratories. Non-standard methods should form operation instructions.


7) The laboratory shall ensure that its personnel training and technical capabilities, facilities and environmental conditions, sampling and analysis instruments and equipment, reagent materials, standard substances, original records and testing/monitoring report formats meet the requirements of non-standard methods.

Technique of Method Validation


The technique used to determine the performance of a method should be one or a combination of the following:
1) Use reference standards or standard substances (reference substances) for calibration or evaluation of bias and precision;
2) Compare with the results obtained by other methods;
3) By changing the robustness of the control test method, such as thermostat temperature, sample volume, etc;
4) Inter-laboratory comparison;
5) Systematic review of the factors affecting the results;
6) Based on the scientific understanding of the theoretical principles and practical experience of the method, the uncertainty of the results obtained is evaluated.

Record of Method Confirmation


1 The whole process of method confirmation shall be reported, and the original records of the whole process shall be attached to ensure the traceability of the method confirmation process. The name of the record can be different according to the confirmation technology used, such as: "record (report) of calibration using reference standard (standard substance)", "record (report) of comparative analysis with a certain detection method", "comparison test results and their analysis", "review report of factors affecting the results of a certain detection method", "record (report) of measurement uncertainty assessment", etc.


2 The laboratory shall maintain the following confirmation records:
1) The confirmation process (the confirmation procedure used);
2) the specified requirements;
3) Determine the performance characteristics of the method;
4) the results obtained;
5) A statement of the validity of the method, detailing its suitability for the intended use.
Preconditions for the formal introduction of the use of 8.5 identified methods


After confirming the method, the technical director shall organize relevant technical personnel (experts in the industry can be invited if necessary) to review and make a conclusive opinion on whether the performance of the method can meet the testing requirements.


After the testing method is confirmed to meet the testing requirements, the technical director shall organize the training and assessment of the testing personnel in time. After the ability to carry out the method has been verified, and the customer's consent has been obtained, and the customer has been informed of the possible risks of the method, it can be officially introduced.