Laboratory quality control

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(Reposted) Laboratory Quality Control ================== Laboratory quality control consists mainly of internal quality control and external quality assessment (competence testing). It is an important part of the quality management system for laboratory accreditation (certification), and its purpose is to ensure the reliability of the test results produced by the laboratory. The reliability of test results has two aspects: first, high precision, which means that the test results are consistent, with little influence from random errors; this is primarily ensured through the implementation of internal quality control ； Another aspect is high accuracy, meaning that the test results are close to the true value, or in other words, the impact of systematic errors is minimal; this can be ensured by regularly participating in external quality assessments. Therefore, for laboratories to obtain reliable test results, they must carry out thorough internal quality control within the laboratory and actively participate in external quality assessment activities. General laboratory quality control activities are as follows: I. The foundation of laboratory quality control. Laboratory quality control is not merely about controlling the testing process; it encompasses all quality activities within the laboratory. Laying a solid foundation for quality control primarily involves the following aspects: 1. A complete, effective, and appropriate quality system ensures that the laboratory’s quality activities are under control ； 2. Good management, clear division of responsibilities, and coordinated collaboration among relevant departments and positions ； 3. Inspectors must adhere to operating procedures and possess the qualifications and skills required for their work. They receive regular training and are allowed to work only after passing assessments; emphasis is placed on keeping their knowledge up to date ； 4. The laboratory facilities and environment meet the testing requirements ； 5. Instrumentation and equipment (measuring instruments) shall be regularly maintained, calibrated (periodic checks), and verified, with proper records kept to ensure they remain under control at all times. 6. Standard materials are kept by designated personnel; when purchasing them, it is necessary to obtain a valid certificate for the standard material from the supplier to ensure its reliability and traceability. Before using the standard material, it should be carefully checked to confirm that it is still within its valid period ； 7. Sample management ensures the integrity and safety of samples ； 8. Data processing, recording, and reporting are accurate ； 9. The testing methods must give priority to **the specified standard methods, and the preparation of work instructions must be carried out under controlled conditions ； 10. External service quality, quality of purchased items ； 11. Develop a quality control plan at the beginning of the year and implement it according to the plan. II. Internal Quality Control Currently, laboratories generally use the following methods for internal quality control: 1. Blank tests, parallel duplicate measurements. As quality control for the routine testing work in physical and chemical inspection. 2. Determination of spiked recovery rate, dual-person (dual-machine) comparison, retesting of retained samples, comparison with relevant testing institutions, preparation of quality control charts ； 3. Use reference materials for internal quality control. 4. Quality control of outliers and critical values: When outliers or critical values occur, retesting is carried out; a report can be issued only if the results from the repeated tests match. Otherwise, the cause must be identified until the correct result is obtained. 5. Analysis and processing of quality control results: Various quality control results are analyzed and evaluated in accordance with the relevant regulations. When the results exceed the allowable range or unsatisfactory outcomes occur, the relevant testers are tasked with identifying the causes and taking corrective actions in accordance with the applicable procedural documents. 6. Quality supervisors conduct regular inspections to identify issues in the testing process in a timely manner, and take appropriate measures to resolve them. III. External Quality Assessment (Capability Testing) On the basis of thorough internal quality control in experiments, actively participate in external quality assessment activities organized by the China National Accreditation Service for Conformity Assessment (CNAS) and provincial (municipal) authorities. In summary, quality control is a task with a long way to go; although it is very tedious, it serves as a \"mirror\" in the testing process.