BIOTECHNOLOGY


this is typically 35 to 100 per cent of the device’s nominal volume. Staying within this range is therefore crucial for reducing the amount of air in the cushion, minimising errors and maintaining the best possible accuracy. In addition, poorly fitting tips can lead to leaking, quickly causing inaccurate aliquot volumes. Tips may also become


misaligned or fall off, interrupting workflows and slowing down liquid handling steps. It’s essential to use high quality, compatible pipette tips – ideally from the same manufacturer as the pipette itself, rather than from a universal supplier – to avoid these common issues and promote consistent volume control.


A common


source of error is caused by temperature differences between


pipettes, tips and liquids


c❝Pipettes


an become less


accurate and may cause sample contamination without the proper care, maintenance and storage


HANDLING NON- AQUEOUS LIQUIDS The calibration of air displacement in micropipettes is performed in a controlled environment with water, so pipetting viscous and volatile non-aqueous liquids – such as glycerol, DMSO, ethanol or Tween 20 – can affect the accuracy of the end result. Viscous liquids attach to the wall of the tip, making it difficult to expel the full volume, while the rapid evaporation of volatile liquids can significantly alter the pipetting volume. Specific techniques are required to ensure the best results when working with these more difficult liquid types.


1


Viscous liquids a) Hold the pipette upright b) Use a slower pipetting speed c) Do not immerse the tip too far into the sample reservoir to reduce the risk of carryover


d) Use low retention, wide bore tips to enable liquids to enter more easily


e) Perform reverse pipetting to prevent incomplete filling or emptying of a pipette tip


Hold the pipette as upright as possible


f) Keep the pipette tip in the solution for longer, 2-3 seconds after aspiration and dispensing, to allow complete liquid transfer


2


Volatile liquids a) Hold pipette as upright as possible


b) Use a faster pipetting speed and work quickly to prevent evaporation


c) Prewet to equilibrate air pressure and humidity to reduce evaporation


PREVENTATIVE DEVICE MAINTENANCE Pipettes can become less accurate and may cause sample contamination without the proper care, maintenance and storage. The best way to prevent this source of error and frustration is to clean and maintain pipettes regularly. The outside of a pipette should be cleaned daily with a lint-free cloth and 70 percent ethanol, and it’s important to perform a leak test and validate the pipetting volumes on a monthly basis to make sure that the pipette is working as intended. If its accuracy and precision are not within specifications, the device needs to be calibrated before further use. Calibration carried out at least every 12 months will help to keep pipettes working at their best. In addition, if the pipette is dropped, then it should immediately be checked for damage and recalibrated before use to ensure it still meets the specifications. Cleaning, maintaining and regularly calibrating pipettes will give them a long lifetime of reliable activity, and also helps to keep users safe from potential malfunction and contamination. In summary, good pipetting


practices, combined with regular maintenance, help to maintain consistent pipetting, leading to fewer manual errors and contributing to more reliable and accurate results. n


For more information visit https://www.integra-biosciences. com/en


www.scientistlive.com 49


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60