ISO 20836-2021 pdf free download – Microbiology of the food chain — Polymerase chain reaction (PCR) for the detection of microorganisms — Thermal performance testing of thermal cyclers
5 Maintenance of thermal cyclers The laboratory shall establish a maintenance programme, where appropriate, and keep records to ensure proper functioning and prevent deterioration of the thermal cyclers.
6 Performance testing of thermal cyclers
6.1 General If the performance testing method of this document is used as a metrological traceable temperature calibration, as a conformity test or as a reference method, the performance test shall be carried out with a minimum number of sensors that represent at least 12,5 % of wells for reaction blocks or chambers < 96 wells or 12 wells for reaction blocks or chambers > 96 wells (see 6.4.5.1) and metrological traceability (see 6.3) shall be provided up to the level of the thermal cycler. If the performance testing method is used for other purposes, such as supplier’s quality control or supplier’s after sales service, the number of sensors may be reduced to a minimum number of sensors that represent at least 8 % of wells for reaction blocks or chambers < 96 wells or 8 wells for reaction blocks or chambers > 96 wells and metrological traceability shall be provided up to the level of the temperature measurement system. In case of individual reaction chambers, each of the individual reaction chambers shall be tested. The decision chart in Figure 1 can be used to determine if the performance test shall be a metrological traceable calibration or a performance test.
NOTE 1 Calibrations that meet the requirements of the ISO/IEC 17025 are considered to be metrological traceable. ISO/IEC 17025 describes when metrological traceability is required and how metrological traceability is established.
NOTE 2 The chemistry- or biochemistry-based normalization and verification kits available at the time of publication of this document offer no traceability to SI and are associated with high measurement uncertainties, and are therefore inapt as a performance testing method. The normalization kits are developed to optimize the optical detection and related software to enable the collection of fluorescent data in a real-time thermal cycler. These kits are not developed for calibration purposes.
6.2 Performance testing programme The laboratory shall establish a performance testing programme, where appropriate, and keep records to ensure that the thermal cycler is capable of achieving the accuracy required and complies with the specifications relevant to the intended use. ISO/IEC 17025-compliant laboratories are required to establish a planned calibration programme in order to maintain confidence in the status of calibration (see ISO/IEC 17025:2017, 6.4). NOTE Guidance on how to determine calibration intervals, particularly when setting up a calibration programme, is provided in, for example, ILAC G24. 6.3 Metrological traceability Performance testing shall be traceable to the International System of Units (SI). Metrological traceability is established by considering, and then ensuring, the following:
a) the specification of the measurand (quantity to be measured);
b) a documented unbroken chain of calibrations going back to stated and appropriate references (appropriate references include national or international standards, and intrinsic standards);
c) measurement uncertainty for each step in the traceability chain is evaluated according to agreed methods;
d) each step of the chain is performed in accordance with appropriate methods, and the measurement results and associated, recorded measurement uncertainties;ISO 20836 pdf download