In the field of precision experimental science, the accuracy and reliability of pipettes are the cornerstone of ensuring accurate experimental results. However, with time and changes in experimental conditions, the performance of a pipette may be affected, causing deviations in its scale or measurement values. In order to maintain the accuracy and reliability of pipettes, calibration and verification have become indispensable links. Although both are designed to ensure pipette precision, there are significant differences in their actual operation.
1. Definition and purpose 1. Calibration: (1) Definition: The activity of determining the indication value of measuring instruments through experiments according to relevant calibration specifications. Usually, the error of the instrument being measured relative to the standard instrument is obtained by comparing it with a higher-precision standard instrument, thereby obtaining the correction value of the indication value of the instrument being measured. (2) Purpose: To determine the relationship between measuring instruments and corresponding standard values to help ensure the accuracy of the values. Calibration is a bottom-up value traceability process whose main purpose is to ensure the accuracy of the pipette during use. 2. Verification: (1) Definition: According to the national metrology verification regulations, it is an activity to determine through experiments whether the indication error of measuring instruments meets the requirements. Verification is mandatory, and its scope is the measuring instruments that are subject to mandatory verification as clearly stipulated in my country's Measurement Law. (2) Purpose: The mandatory comprehensive assessment of the measurement characteristics of measuring instruments is a top-down value transfer process. The purpose of verification is to ensure that pipettes comply with national or industry measurement standards and have legal effect.
2. Basis and standards 1. Calibration: (1) Basis: The basis for calibration can be calibration specifications or calibration methods. These specifications can be uniformly stipulated by the state or formulated by oneself. (2) Standard: Calibration is usually compared with a standard with higher precision to obtain the error value of the pipette. 2. Verification: (1) Basis: The basis for verification is the metrological verification procedures approved and published in accordance with legal procedures. (2) Standards: Verification must be carried out in accordance with the steps of metrological verification regulations and has strict legality and normativeness.
3. Subject and method 1. Calibration: (1) Subject: The subject of calibration is a person with calibration qualifications. (2) Method: Calibration can be carried out by self-schooling or external schooling. If you have the conditions, you can choose to perform calibration yourself to save costs. 2. Verification: (1) Subject: The subject of verification is a verifier who has passed the assessment and holds relevant certificates. (2) Method: The verification must be carried out at a qualified measurement administrative department or a legally authorized unit.
4. Period and content 1. Calibration: (1) Period: The calibration period can be determined by yourself based on the frequency of use or risk level of the measuring instrument. Calibration can be performed periodically or irregularly, or even before use. (2) Content: The content of calibration is mainly to evaluate the indication error of measuring instruments to ensure the accuracy of the value. 2. Verification: (1) Period: The verification period must be carried out in accordance with the provisions of the metrological verification regulations and cannot be determined by yourself. (2) Content: The content of the verification not only includes calibration content, but also requires verification of related items. Therefore, verification can replace calibration, but calibration cannot replace verification.
5. Results and effectiveness 1. Calibration: (1) Results: Calibration does not require a determination of passing or failing, only information such as range, error or measurement uncertainty needs to be given. Calibration results can be recorded in a calibration certificate or calibration report, or expressed in the form of calibration factors or calibration curves. (2) Validity: The calibration results do not have legal effect, but can be used as the basis for internal quality control and calibration of the laboratory. 2. Verification: (1) Result: The verification result must determine whether the measuring instrument is qualified or unqualified according to the value error range specified in the verification procedures. A verification certificate will be issued to those who pass the test, and a verification result notification will be issued to those who fail to pass the test. (2) Validity: The test results have legal validity and are the basis for whether the measuring instrument can be used legally.
Although pipette calibration and verification are both key links to ensure experimental accuracy, they show obvious differences in terms of definition, purpose, basis, execution subject, cycle, content and result effectiveness. Calibration, as a bottom-up traceability activity, focuses on determining the pipette error through comparative measurements and making corrections accordingly to ensure its accuracy in daily experiments. Verification is a comprehensive assessment of the measurement characteristics of pipettes based on legal procedures and national metrology verification regulations. It is mandatory and legally binding and aims to ensure that pipettes comply with national or industry measurement standards.
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