Courtesy of DakoCytomation
NASA scientists, in conjunction with Guava Technologies of Hayward, Calif., recently announced a compact prototype flow cytometer that functions in zero-gravity, for use aboard the International Space Station. Most investigators looking for a portable or benchtop system will have more down-to-earth needs, but the announcement reveals just how small these tools are getting.
In fact, you can outfit your lab with a simple laptop-sized cytometer for as little as $10,000, or spend well into six figures on a multilaser system capable of measuring more than a dozen different colors. How then should you decide? On the following pages, we compare 24 cytometers by sorting ability, throughput, speed, excitation sources, and number of detection parameters.
BEFORE YOU BUY, CONSIDER THESE...
Too often, scientists will rush to buy a cytometer without knowing whether the machine meets the needs of their lab. "Many purchasers buy too little or too much instrument," says William Telford, director of the National Cancer Institute's Experimental Transplantation and Immunology Branch Flow Cytometry Core Laboratory. "Have a clear idea of what you really need before you buy."
But, make sure to consider future needs, adds Brendan Yee, business manager for Affordable Cytometry Solutions at Beckman Coulter of Fullerton, Calif. Choosing a system that works with different light sources and interchangeable filters can help maximize flexibility, he suggests.
J. Paul Robinson, president of the International Society for Analytical Cytology (ISAC) and director of the Purdue University Cytometry Laboratories in Lafayette, Ind., advises potential buyers to consult with colleagues doing similar work to see how well their instrument fits their research goals. "Sometimes, this is one of the best ways of identifying a system that will work for you." The Pur-due University Cytometry Laboratories runs an online discussion list
Selected Flow Cytometers
For cytometers, greater sophistication means increased complication. "Once you move to anything that is likely to have some variation, the problems start," says Robinson. "Cells clump, antibodies may not be properly titrated, volumes may be incorrect, cell numbers too few, high background, incorrect voltages on photo-multiplier tubes."
John P. Nolan, an investigator at the La Jolla Bioengineering Institute in California, uses a variety of BD Bioscience machines. "The BD sorters perform well, although the more complicated systems tend to have more bugs," he says.
Thus, you may need to hire some help. "A great instrument in the hands of an incompetent technician makes a lousy instrument," notes Robinson. "The converse is true as well. An instrument that may not be considered highly from a technical perspective can produce really good data in the hands of a competent technician."
If you are running only a handful of samples per day, you probably don't need automated, high-throughput capabilities. If you plan to run dozens of samples at once, however, a machine that can automatically load samples from tubes and 96-well plates may be worth the extra cost.
Many instruments come with high-throughput samplers. They can also be purchased separately and added later, if needed. "We recently purchased BD's high-throughput samplers," says De Rosa. "These generally work well, but have some problems with a small amount of carryover between wells."
NEW VERSUS USED?
Finally, if price is a concern, consider a secondhand instrument. "We have bought used systems and have been happy," says Nolan. "We generally cover them under a service contract for the first year until we are sure they are running well."
"For analyzers that are in the four- to six-years of age category, this is a great option," says Robinson. "You get good value."
"Older analyzers, like the BD FACScan or the Beckman Coulter XL, are well-designed and can operate for years if properly cared for," says Telford. Find a reputable used system dealer that can provide a history of the instrument, a quality refurbishment, and adequate postsale service, he advises.
"We have had good luck with such companies as Phoenix Flow Systems, Cytek Development, CytoServe, and Automation Lab Technology," Telford notes.