Scientists can spend several hours a day–sometimes every day–pipetting. If this work is not done properly, with the right tools and skillsets, lab professionals can suffer sample loss or contamination, project delays and even physical injuries. These risks demonstrate why proper pipetting practices are so important, but where should you begin to make changes? Below are three tips you can implement today to help reduce time spent pipetting, improve liquid handling accuracy, mitigate risk of injury and, ultimately, start pipetting like a pro.
Pick the right pipette
Before you even begin pipetting, make sure the tool you’re using is right for the job. Pipettes come in a variety of different models and sizes for a reason. Make sure you are considering both the type of sample–is it aqueous or viscous?–and the volume you are transferring. If you are handling heavier liquids, consider using a positive displacement pipette, as opposed to an air displacement pipette which is better suited to lighter, thinner liquids. Similarly, you’ll want to select a pipette with a working range appropriate for the sample volume you are handling. If the task at hand requires repeated dispensing of the same volume or reagent, consider a repeater/stepper pipette or use an electronic pipette with a multi-dispensing function such as Thermo Scientific™ ClipTip™ and Finnpipette™ Pipettes, which allow for successive dispensing without refilling.
Finally, remember to keep throughput in mind. Life science applications, for example, commonly necessitate the use of 96- and 384-well plates. Multichannel pipettes would be the ideal choice as they accommodate multiple transfers, thereby reducing the number of aspirations and dispenses required to fill a plate. You may also want to consider the E1-ClipTip Equalizer Multichannel Pipette to add an additional layer of convenience with adjustable tip spacing. Users can adjust the distance between tips by simply sliding a scale, saving as much as 90 percent of their time compared to manual single channel pipettes and reducing physical burden on the handler.
Practice proper pipetting procedures
The right tool won’t take you far if it’s being used incorrectly. It’s easy to go on autopilot when carrying out a recurring task like pipetting; however, proper form is essential to avoid many of the most common liquid handling errors. These include tip loss, pipette leakage or transferring incorrect volumes of a sample. While these mistakes can seem minor, the margin of error for pipetting is actually quite small. Leakage from an improperly locked pipette tip can reduce accuracy by as much as 50 percent.
Electronic pipettes, such as E1-ClipTipElectronic Pipettes, are becoming popular because they automate many of the steps in the standard pipetting procedure, offering digital functions to adjust volume, dispense liquid and even electronically eject a tip. However, even with electronic pipettes it is important to realize the factors affecting your pipetting accuracy and reproducibility so you are able to reach the best results.
Below are the steps to properly use a manual air-displacement pipette, a process that incorporates fundamental pipetting actions that any liquid handler should know:
- Set the volume on the pipette.
- Depress the plunger.
- Immerse the tip to the specified depth and release the plunger to its resting position slowly. (The pipette should be kept straight for the most accurate aspiration.)
- Wait for the liquid to flow into the tip. When handling higher volumes, it’s recommended to wait a few moments for the liquid to level off and the pressure inside the tip to settle.
- Holding the pipette at 10-45 degrees, place it against the wall of the receiving chamber and depress the plunger to the first stop.
- Wait one second and then depress the plunger to the second stop.
- Slide the tip up the vessel wall to remove any residual liquid from the outer tip surfaces of the pipette.
- Return plunger to a resting position.
Visit our online pipetting resources to improve your results with further tips on proper technique.
Be mindful of posture and grip
With the right pipette and fundamental know-how at the ready, the last step to perfecting the process is your posture. The concentration required for pipetting makes it easy to overlook factors like your stance and grip, but it’s important to be mindful of them. It’s been shown that daily pipetting can place a strain on muscles, ligaments and tendons if not done
properly. Ensure your environment is set up to reduce risk factors and allow proper posture. Best practices include:
- Pipetting at a workstation aligned to your height – a lab bench that is too tall or short for your physique can place undue pressure on upper limbs or cause unnecessary hunching that can lead to back and neck strain.
- Having a lumbar-supporting chair at the ready – this is particularly important if you’ll be pipetting for hours on end. An adjustable chair is ideal so it can be customized to the user. Ensure your feet are resting comfortably on the floor and that the chair sits at a height appropriate to the workbench, so you can sit close to the pipetting station.
- Relaxing your wrist – ensure it is not extended, flexed or rotated. If you’re experiencing any of these positions, consider selecting a different pipette that conforms to your grip.
- Testing thumb pressure – your thumb should not have to apply significant force to transfer liquids or eject tips. This could aggravate hand, shoulder and back muscles if done regularly or for prolonged periods of time. If this is a recurring problem, think about switching to a pipette designed with ergonomic considerations in mind. The E1-ClipTip Pipette, for example, uniquely allows for index finger pipetting action to let thumbs relax during pipetting.
- Placing your solutions, samples and other equipment within reach – make sure everything you need is within your grasp before you start pipetting to avoid uncomfortable twisting, bending or stretching.
Pipetting may be tedious at times, but it doesn’t have to be uncomfortable or frustrating. Consider these tips before beginning your next project for an efficient, reliable, and ergonomic pipetting experience. To find the right pipetting solution for you, click here.