Product Focus: Evaporators
Learning to use evaporation starts very early in chemistry. For students, the process takes a very simple
approach, maybe just putting a solution in a beaker over a flame and waiting. That technique, though,
doesn’t provide the sophistication, control, or throughput that advanced techniques require. Consequently, scientists can use dedicated evaporators.
Capturing the Required Control and Maintaining it Depends on the Right Platform and Care
At the U.S. National Institutes of Health’s Chemical Genomics Center, analytical chemistry team leader William Leister needs throughput and flexibility in evaporation. For one thing, he uses a wide range of containers: test tubes of various sizes, in racks that hold different numbers of test tubes as well as 96-well plates. Consequently, he says that he needs an evaporator that provides “flexibility of rack configurations.” He adds, “For our needs, the ability to control each side of our evaporator independently is very important.”
Keep it rotating
“Rotary evaporation is a staple in chemistry labs, like using a hot plate or overhead stirrer,” says Jim Dawson, president of Heidolph North America (Elk Grove Village, IL). He adds that chemists get very particular about this device. “How it’s set up and used is very personal,” he says.
To keep this device working right, says Dawson, you “need to use the right vacuum pump with the appropriate vacuum control for the application.” That control, though, gets very application-specific. As Dawson explains, “Sometimes you need precise vacuum control, but sometimes a basic manual knob is enough.” Beyond that, the required care involves the seals, glass joints, and tubing. Those pieces must be maintained to keep the desired level of vacuum during evaporations.
In buying a new rotary evaporator, Dawson encourages customers to consider the safety and ease-of-use features. After that, he says that you should look for the level of control that you need. To confirm what that is, and to keep a device operating effectively as long as possible, Dawson says, “I can’t stress enough the value of face-to-face support— helping the customer with the purchase, setting up the instrument, and offering support through the lifetime of the device.”
Controlling contamination
Today’s evaporators often handle multiple samples at once, but each must be processed without being impacted by the others. So Jim Jacso, director of sales and engineering at Glas-Col (Terre Haute, IN), says that scientists must make sure that there’s no cross-contamination. That requires careful control of the airflow. “Slow airflow at first prevents cross-contamination,” Jacso says.
A user must also keep a system in excellent condition. To do that, Jacso emphasizes keeping the needles clean. “If holes are plugged up in the needles,” he says, “you get wells that aren’t drying down.” In processes that involve acids, the needles can get corroded and plugged. Some systems use stainless-steel needles; others use polytetrafluoroethylene. “Choose the proper needles depending on what you are doing,” Jacso says.
If a system includes a regulator, as many do, it must be maintained as well. “Make sure that it’s up to speed and functional,” Jacso says.
The world of evaporators moved beyond a beaker over a flame long ago, and today’s options can get overwhelming. “You can get ones that shake, heat, heat a gas,” Jacso explains. “You can also get programmable evaporators.” He adds, “There is an evaporator for just about everyone. You can spend under $1,000 and up to $20,000.”
For additional resources on Evaporators, including useful articles and a list of manufacturers, visit www.labmanager.com/evaporators