Pipettes should be regularly calibrated to ensure they continue to perform precisely and accurately. Here, John Brooks at Trescal, the international specialist in calibration and measurement solutions, explains why. In this article he will demystify the process to reveal what good looks like when it comes to implementing a successful pipette calibration programme.
“It is clear that more needs to be done to ensure that pipette calibration is tailored around the needs of a laboratory and that maintenance is not neglected,” says Trescal’s John Brooks, who heads up the Trescal Stevenage branch, a centre of expertise for pipette calibration in the UK. As a result, John and his team know only too well that with pipettes being a widely used laboratory tool - often in constant operation and frequently subjected daily to a number of external factors - performance can deteriorate with each use. John explains, “This can be caused by anything from contact with fluid which causes corrosive effects, to the general wear and tear caused by pipette handling.”
With this in mind, it isn’t difficult to see why a pipette needs to be well maintained through regular calibration intervals. However, due to the heavy reliance on the equipment, it can be a struggle for some to commit to a regular testing and maintenance programme.
How frequently should pipettes be calibrated?
As there is no current legislation on how often pipettes should be tested, it is down to users to make an informed decision based on usage. However, the NPL good practice guide No 69 recommends that every pipette in use should be tested on a regular basis to determine the accuracy and repeatability of the volume of liquid it delivers.
Trescal UK follows the NPL good practice guide further, to also recommend that an assessment should be made to determine the frequency of testing appropriate to the use the pipette receives and the accuracy required from it. This should be at least once a year but wherever possible every three to four months. The factors to be considered include the amount of use, number of users, type of liquid dispensed and any manufacturer’s recommendations.
Taking a good look at the types of pipettes in use will also be a good indicator. Mechanical action pipettes, unlike the original glass pipette, contain many internal parts and could be at higher risk of a failure as there is more to go wrong. Problems might not always be evident to the operator, so also take this into consideration and ensure that equipment is checked frequently even if the pipette is seemingly working correctly.
From this is it is clear that a quality calibration provider will be able to help identify the best intervals for testing and can also base maintenance schedules on laboratory experience to help minimise the occurrence of predictable failures in most cases.
What does pipette calibration involve?
When it comes to the process involved, the calibration will involve a skilled engineer inspecting the device for any signs of wear and tear, contamination or corrosion from fluids, poor pipette handling and general damage.
The calibration process follows the guideline of BS EN ISO 8665: 2002 standard and the NPL good practice guide, where compliance is tested by very accurately weighing multiple samples of dispensed fluid in a carefully controlled and repeatable manner.
The engineer will then be able to make adjustments to the pipettes to optimise performance, and, if required, replace O-rings and seals, then clean and re-lubricate prior to final compliance testing.
What to consider when arranging pipette calibration?
Calibration providers should be accredited to ISO/IEC 17025, which demonstrates competency in calibration. However, the BS EN ISO 8665: 2002 standard, which is the most critical ISO standard for calibrating piston-operated pipettes, burettes, diluters, and dispensers, is much more detailed and specific to pipette calibration.
Another factor to keep in mind is the schedule of the laboratory, which is crucial to keep in mind when planning a pipette calibration programme. Wherever possible, minimising downtime should be the goal. Many calibration providers, including Trescal, can offer onsite calibration services which means a significant amount of time is saved by not having to transport products between the testing facility and laboratory.
It is important to check that a calibration provider is certified to undertake onsite calibration services, so always check the UKAS schedule of accreditations and ask for proof of compliance.
How much will it cost?
Costs will vary depending on the type of pipette and calibration required. However, an appropriate maintenance regime will bring savings in the long run. With regular pipette calibration, the longevity of equipment is improved, meaning businesses are able to reduce the likelihood of problems occurring and the replacement of pipettes, saving potentially thousands of pounds.
Overall, it is important to have an open dialogue about requirements to work towards the most reliable and effective solution. A comprehensive calibration programme that meets the needs of laboratories is achievable with the help of a quality calibration provider. Additionally, with options including onsite calibration services, there should also be a solution to keep downtime and costs to a minimum.
To find out more about Trescal visit www.trescal.com or to enquire about Pipette calibration services please contact info.uk@trescal.com
02/11/2017
