This difference explains how traveling or onsite pipette calibration providers can be accredited to ISO but not to ISO Adherence to the ISO standard covers air displacement pipettes and positive displacement pipettes, single channel and multichannel pipettes both fixed and adjustable volume as well as both manual pipettes and automated pipettes, often called motorized pipettes or electronic pipettes.
ISO accredited laboratories like Pipettes. The standard characterizes both the maximum permissible systematic error, as well as the maximum permissible random error limits for a device at specific volumes ranging from ,uL. These errors are doubled for multichannel pipettes. ISO states that the primary methodology for measurement of piston-operated pipettes and related measurement apparatus is through gravimetric measurement analysis.
Included are the minimum balance requirements at each test volume, important for reporting measurement accuracy at the appropriate resolution. Pipette measurements face the same challenge for many providers. This standard also requires control not just monitoring of test conditions, along with minimum data points for a valid representation of device performance and measurement analysis. To be considered valid by ISO , pipette measurements must occur in a strictly controlled, vibration-free test environment.
The acceptable ranges of environmental conditions are defined as:. The ISO standard defines a step-wise procedure for generating valid, reliable measurement data. Procedures include proper technique for tip installation, pre-wetting, aspiration and dispensing technique, measurement container requirements, required number of measurements, evaporation rate determination and time lapse for test completion.
Regular FDA audits are required for all drug development labs, helping to ensure data integrity and proof of efficacy. However, supporting your science with the assurance of an ISO compliant pipette calibration service provider, ensures that the pipette measurements are accurate and reliable.
As FDA audits validate proper drug development and quality controls, ISO accreditation audits provide the same integrity for pipette calibration providers.
However, when an auditor evaluates compliance of a pipette service provider to ISO standards and controls, they are raising the bar and promoting standards-based calibration. For pipette service providers, ISO compliance improves service integrity, so drug development labs provide quality products, supported by trustworthy, reliable service providers.
In such cases, the design shall prevent unintentional readjustment. If the user readjusts the piston pipette, it shall be clearly and unequivocally indicated on the outside of the piston pipette that readjustment has been effected. The user shall mark the outside of the piston pipette with the name of the liquid for which the nominal volume now applies. This information shall also be recorded on any certificate of conformity.
When the tip is touched against the wall of a vessel in successive operations, any amount of liquid remaining in or around the dispensing orifice of the tip shall be consistent. NOTE This requirement can be assessed by comparing errors of measurement using tips which have and have not been sterilized. To assure their metrological performance they shall conform to 5.
NOTE Variability of amount of externally retained liquid or an incomplete seal will contribute to poor precision when testing to ISO Pipette tips made of plastic for piston pipettes with air interface are designed for single use. They shall not be cleaned for reuse as their metrological characteristics will no longer be reliable.
Various material may be used for the plunger, such as metal or plastic, and the capillary, such as plastic or glass. These pipette tips may be reusable or disposable both plunger and capillary is changed at each sampling. The conformity test shall be carried out in accordance with ISO by a test house or other authorized body prior to the issuance of a certificate of conformity. For conformity tests, the maximum permissible errors of Tables 1 and 2 shall apply.
Annex B lists parameters which influence the metrological performance of piston pipettes and recommendations for their handling. For the maximum permissible errors of piston pipettes with intermediate nominal volumes between those given in Table 1, the absolute values for the next greater nominal volume shall apply. Expressed as the deviation of the mean of a tenfold measurement from the nominal or selected volume see ISO , 8.
Expressed as the repeatability standard deviation of a tenfold measurement see ISO , 8. For the maximum permissible errors of piston pipettes with intermediate nominal volumes between those given in Table 2, the absolute values for the next greater nominal volume shall apply. In the conformity test, the maximum permissible errors for the nominal volumes in Tables 1 and 2 apply to every selectable volume throughout the useful volume range of the piston pipette; i.
NOTE It is recognized that the errors of measurement of intermediate volumes in the useful volume range of a variable-volume piston pipette may be considerably better than those specified for the nominal volume of the piston pipette. Repetitive piston pipettes with a continuously selectable volume shall be considered as variable-volume piston pipettes of type D2 and the maximum permissible errors of Table 2 shall apply.
Each channel of the multi-channel piston pipette, considered independently, shall meet these specifications. In the case of variable-volume multi-channel piston pipettes, the maximum permissible errors for the nominal volume apply to every selectable volume throughout the useful volume range see 7.
In such cases, the evaluation of the maximum permissible errors shall be performed using the alternative tips with the method of test specified in ISO Before the conformity evaluation of the piston pipette with the alternative tips, it shall be ascertained, that the piston pipette in combination with the original tips conforms to the metrological requirements specified in this part of ISO Users may test the metrological performance for routine quality assurance procedures of the total system of — piston pipette and tip type A and operator, or — tip and piston combination type D and operator in accordance with ISO or with alternative test methods see note to clause 1.
In addition, the following information should be marked: f. Where appropriate, a conformity mark may be affixed to the piston pipette. The supplier should indicate, where appropriate, procedures for sterilization of the pipette tips. Annex A normative Information to be provided by the supplier for the user of piston pipettes and tips. This information shall be in the published specification on which the purchase contract is based, or in instructions that accompany the piston pipette, or in the certificate of conformity and shall be as follows.
Any suggestions as to the basis on which a minimum routine testing protocol should be established by the user or a reference to this part of ISO shall be specified. Upon request, information regarding the interaction of the materials of the piston pipette with organic and inorganic solutions and solvents shall be provided.
Recommendations that piston pipettes are always stored vertically to avoid fluid ingress into the interior shall be specified. Table B. Determinable by Observing barometer at the measuring or working place Comparing the density of the liquid to be pipetted to that of water. Sufficient prewetting of pipette tip; Dripping tip or drop hanging from the observing ISO tip. Variations in pipette temperature, ambient temperature and the temperature of the liquid to be pipetted.
To the extent possible, the Measuring the temperature of air and temperature of the pipette, room medium; measuring of pipette and liquid to be pipetted should be temperature impossible the same. Indication of possible error of measurement is not realistic as it depends on the liquid to be pipetted.
For detailed information regarding possible errors of measurement refer to references [1], [3] or [4].
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