For those of us who calibrate on a daily basis, the repeated routine of pipetting may have become almost second nature. In fact, a metrology-centric calibration program should provide the standardized expertise necessary for proper performance assessment and maintenance. However, periodically brushing up on the fundamentals of practice and procedure can refresh your skills, correct errors, and remind you that even the smallest mistakes can lead to major ramifications in the lab space. Understanding your process and having mastery of your chemistry lab supplies, or biology techniques, will play a huge role in your success or failure. So let’s go back to the basics to ensure the highest quality of service and measurement at every turn with these 5 things you need to know about pipette tips:
1. Proper fit: Despite what some pipette manufacturers might advertise, there is no such thing as a universal fitting pipette tip. To ensure accurate results and reduce the risk of error, be sure to use trial and error when fitting pipette tips. The right tip will install fairly easily without applying a lot of force and will stay in place on the pipette.
2. It doesn’t fit if…: Chances are it’s the wrong tip fit if the tip ejector doesn’t function properly in releasing the tip. If the pipette seems to be in good working order, but liquid is leaking assume it may simply be the wrong tip. Many tips come with colors to match them to the corresponding pipette; if the colors don’t match up, the tip is likely not meant for that pipette. For example, a yellow tip is intended for pipettes with yellow markings, such as a 20-200uL pipette.
3. Sealing rings: To create an air tight seal between the tip and pipette, a sealing ring located on the pipette nozzle can be a useful feature. Though not absolutely necessary, the rings help minimize “leaking,” increase accuracy, and reduce error during testing.
4. Low Retention tips: With today’s air displacement pipettes, all the liquid in a pipette tip is part of the measured volume. Low retention tips reduce liquid residue from adhering to the tip’s inner wall and maximize the liquid dispensed from the tip. This choice would be best when performing tasks that require volume measurements down to the lowest uL volumes.
5. Barrier/filter tips: These types of tips contain a liquid barrier (sometimes called a filter) located in each tip and used to prevent contamination of your pipette. The barrier stops liquid from entering into the pipette during use. Cross contamination can occur with even the slightest technique error, so barrier tips are a good preventative measure.
Experienced lab technicians should be able to cross all 5 of these basic pipetting reminders off their quality checklists. However, if any of the above reminders has triggered a light bulb making you realize you have overlooked something in your pipetting practice, be sure to revisit your process. After all, it’s never a bad idea to refresh your approach to the routines you perform every day.