If you want to get the most accurate results when using pipettes in experiments, then you need to have them calibrated frequently. However, calibration isn't the only factor that causes inaccuracy with pipettes. Here are 3 reasons you could be experiencing accuracy issues.
You're Using It Wrong
One of the most common causes of poor pipette accuracy is poor pipette technique. If you're not holding your pipette in the right position and focusing on smooth drawing and ejecting, your results won't be accurate — even if the pipette is properly calibrated.
In general, you should draw (aspirate) with your pipette held at a 90-degree angle to the liquid's surface, and you should eject (dispense) at a 45-degree angle. When aspirating, make sure the tip is slightly below the surface of the liquid to avoid drawing in air; when dispensing, eject the liquid just below the surface of any existing liquid in the receptacle or dispense against the side of the receptacle if it's empty. Remember to release the pipette's plunger slowly and smoothly so you don't end up with air bubbles, and always make sure all the liquid has exited the pipette when dispensing.
You're Storing It Wrong
Frequent calibration may be the best way to keep a pipette accurate, but it won't make much difference if you let a pipette get damaged. Often, pipettes get damaged due to improper storage, which then leads to inaccurate aspirating and dispensing. To keep your pipette in top condition at all times, always store it upright in a cool, shaded, dry environment. This prevents corrosion and weathering, ensuring that the inside of your pipette functions correctly for a long time to come.
You're Using the Wrong Tip
A pipette is only as good as its tip, so it's crucial that you make sure you're using the right tip for the job. When purchasing a tip, it's best to always choose one that's recommended by your pipette's manufacturer. Other tips may be cheaper, but if they're not designed for your specific equipment, they could affect accuracy. You'll know a tip is good if it's made from high-quality polypropylene and marketed as chemical-resistant and heat-resistant.
Once you've got the right tip for your pipette, try to inspect it frequently for scratches and bends as these can have a big impact on your results. A damaged tip should be replaced as soon as possible for the best accuracy.
If none of these issues apply to you or if addressing them doesn't fix your problem, then it's time to hire calibration services to look at your equipment.