The aim of the calibration procedure is to establish the accuracy of the equipment being used. This helps to control for errors and uncertainties, ensuring that the data collected is reliable and accurate.
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Why calibration is important in the pharmaceutical industry
Technological development has brought with it many benefits, however, it has fostered a new way of working where high tech equipment advertises that it offers precise functioning without human intervention. Within the pharmaceutical industry, calibration of equipment is an essential part of the testing process, without it, the accuracy of the data collected can not be guaranteed.
Weighing processes used in the pharmaceutical industry vary greatly, and there is no one method of calibration for all. What does remain constant, however, is the need to observe the calibration procedure as an essential part of the test procedure within a pharmaceutical laboratory: an essential measure to prevent error.
Validation, qualification, and calibration
The processes of validation, qualification, and calibration go hand in hand and are equally important to ensuring the quality of data collected in a pharmaceutical laboratory. This triad of processes is often seen as integral to the testing process.
Validation refers to the precise manner of gathering sufficient data for providing statistically reliable results. When this process is attributed to equipment it is known as qualification. Calibration is the third step, which is necessary to prove that a piece of equipment is suitable for producing trustworthy data.
How to calibrate a balance
In order to be certain that the calibration technique can be relied on, it must be carried out with qualified instruments and only by an accredited laboratory. Calibration is required for all equipment used for measuring, not just balances. The calibration procedure should involve assessing the laboratory’s entire needs for calibration.
Each type of balance has a calibration technique that is adjusted to suit it, and all laboratories should have their own calibration procedure that is essential to be known to all staff involved in the testing process.
Balances should not only be calibrated at the beginning of use, but also at specified intervals during testing, and any balances that do not meet the calibration criteria should simply not be used. If this is found during the testing, an investigation should be done to establish whether the inaccurate balance could have impacted the data collected.
Records of the calibrations undertaken throughout the testing period should be taken down in case reference to them is required later.
There are two primary methods of balance calibration, each of which is discussed in more detail below.
Types of calibration
Calibration of a balance can be performed in two ways, either using internal or external calibration weights.
Internal weights
It is common for electronic balances to have one or more internal calibration weights installed into their systems. Calibration using internal weights can be performed when selected by the user, when a specified temperature change occurs, or following a specified elapsed time period.
Internal calibration adjusts the balance back to its zero point, adjusts the maximum load of the balance, and in the cases where two weights are used it will also adjust the midpoint of the balance linearity. Often, balances with internal calibration weights will also run performance checks, allowing the user to check things like the difference between the measured and recorded mass of the calibration weights.
External weights
External weights used for calibration must meet specifications outlined by the International Organization of Legal Metrology (OIML). There are parameters set regarding suitable materials of construction, the shape and permitted tolerances of external weights.
There are also guidelines regarding the information on weight classes with means of adjusting the weights during recertification. External calibration methods must satisfy the boundaries outlined by the OIML.
External weights must be constructed of austenitic (non-magnetic) stainless steel, manufactured with a hollow center where small stainless steel ball bearings can be added or removed to return the weight to tolerance. These weights themselves must be recalibrated at least every two years to ensure their accuracy.
Why is calibration often outsourced?
In the pharmaceutical industry, the calibration of balances is often outsourced, and the option is becoming more popular over time. Biopharmaceutical manufacturing often emphasizes the speed at which it can get products out of the research and design phase to being commercially available.
This is the major driver for outsourcing calibration, because it is often a faster method than having research teams do it in-house. There is a trend in the industry to only focus on conducting those processes that add the most value, anything else is being outsourced rather than using internal resources. This has led many pharmaceutical laborites to reassess their calibration practices and outsource them to calibration service laboratories.
The past two decades have seen a steady rise in this trend, and out of this highly specialized companies have grown, offering reliable and cost-effective qualification, validation & calibration services. It is ushering in a shift in standard laboratory practice in the pharmaceutical industry.
Sources:
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Benvenuti, M. (2019). Validation, Qualification and Calibration in a Pharmaceutical Facility. [online] Sgs.com. Available at: https://www.sgs.com/en/news [Accessed 12 Nov. 2019].
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Erickson, J. (2019). [online] Files.alfresco.mjh.group. Available at: http://files.alfresco.mjh.group/alfresco_images/pharma//2014/08/22/238325c1-8373-4382-b758-374255558829/article-10565.pdf [Accessed 12 Nov. 2019].
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Resource.npl.co.uk. (2019). [online] Available at: http://resource.npl.co.uk/docs/science_technology/mass_force_pressure/clubs_groups/instmc_weighing_panel/pharmaweigh.pdf [Accessed 12 Nov. 2019].
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