Few labs these days could survive without pipettes. Many assays require pipetting, and the increasing size of multiwell plates demands more steps than ever. Likewise, many experiments and processes—both in academia and in industry— must be validated, especially when regulatory oversight could be involved. Consequently, scientists demand increasing capabilities from pipettes.
According to market research conducted by Hamilton Company (Reno, NV), says product manager Devon Bateman, scientists seek four improvements in new pipettes. The first is process control, which Bateman describes as “something that would aid in reproducible results and increased accountability.” Bateman adds, “Manual pipettes are all based on how the lab technician manually adjusts that pipette, and they can make an error.” The second desired improvement is increased lab efficiency. “As labs get more money conscious, they must increase throughput to decrease the cost per sample,” says Bateman.
That often depends on pipettes that are easier and faster to use. The third involves fatigue. “Carpal tunnel syndrome is very expensive for labs,” Bateman says. “Scientists want a lighter-weight hand device to maximize all-day performance.” The last topic involves increased accuracy. “This is especially important in forensics environments,” Bateman says, “because they are bound by law to prove that their results are true.”
The most accurate pipetting requires automation. “To provide full validation and have traceability that measurements are accurate,” says Bateman, “you need automation robots that really fine tune the process. With hand pipettes it’s getting better, but you can’t really control the process start to finish.”
“The main move today is toward using electronic pipettes, and there are a few reasons for that,” says Melinda Sheehan, Ph.D., product manager, liquid handling at Eppendorf North America (Hauppauge, NY). “One is ergonomics, and another, by far, is reproducibility.”
With an electronic pipette, everyone can use it consistently. “It doesn’t matter how hard a user pushes down on a button,” says Sheehan. “You can just pass an electronic pipette to a colleague, who will get the exact same results.” She notes that electronic pipettes cost more than manual ones, but she thinks the advantages outstrip the cost. “With a manual pipette, you might have to do more replicates and even redo complete experiments if pipetting errors arise,” she says. “An electronic pipette pretty much stays clear of the errors that affect precision.”
Also, Sheehan notes, electronic pipettes provide some programming options. “You can set the volume and the speed,” she says. “Some liquids need to be aspirated or dispensed at a certain speed.” As an example, she says that glycerol needs to be aspirated and dispensed very slowly. “Everyone can set the same speed for a specific liquid across the lab to ensure consistency,” she says.
Some electronic pipettes do even more. For example, some can mix, aspirating and dispensing the same solution a few times. Some electronic pipettes can also aspirate a large volume and then dispense it in smaller volumes to multiple wells. “For ten wells, it takes 20 movements—ten aspirations and ten dispensings— with most pipettes,” says Sheehan. “If one includes a multi-dispense mode, you can do the same thing in 11 moves—one aspiration and ten dispensings.”
Increasing the throughput
As screening applications move to more labs—even smaller academic ones—more users require higher- throughput options for pipetting. “In the past ten to 20 years, screening applications have multiplied,” says Michael Beier, liquid handling product manager at INTEGRA Biosciences (Zizers, Switzerland). “Before it was limited to specialized labs, but now these screening assays are available to the whole scientific community.”
To work with the higher-end multiwell plates, screening facilities often use liquid-handling robots, which can be expensive to purchase and complicated to program. Now researchers purchase manual and electronic benchtop pipetting systems.
For 96-channel pipetting, says Beier, “bench-top models have evolved and you have a couple of choices.” He adds, “Electronic ones offer more flexibility over manual ones.” Some applications require as little as one microliter per channel to aspirate and dispense. “So the demand for accuracy and precision is just as important as it is with a robot.” Plus, the benchtop models are easy to set up and program. “You can turn it on and change volume as in a normal electronic pipette, and then you can start working,” says Beier.
This trend in increasing throughput will continue. Some benchtop pipettes already provide 384 channels. Beyond that, though, robots will still rule.
Find the right features
The accuracy and life of a pipette depends on the starting product and how it gets maintained. “If you keep products serviced and keep them out of disrepair, you don’t need to replace them and they’re easier to use,” says Sheehan. Also, she believes that the manufacturer can help with serviceability. “The easier that the manufacturer makes a pipette to repair, clean, and maintain, the more likely the customer will do it.” Therefore, she advises users in the market for a new pipette to “know if it will be easy to maintain.”
Different pipettes also offer different features that might matter more to some users than others. When asked what she’d like to see on more pipettes, Cary Ann Gallini, research assistant II at the Harvard School of Public Health (Boston, MA), says, “A locking mechanism to prevent drift when pipetting multiple samples with precision is key!” She adds, “I would also like to see more ergonomic pipettes on the market. VistaLab Technologies [Brewster, NY] makes a nice design, but I believe, because there is a lack of competition when it comes to pipettes with nontraditional designs, their price remains pretty high. It would certainly be hard to convince my principal investigator to purchase a whole new set.”
In the end, the right pipette depends on the application and the user.