Centricon Plus-70 centrifugal filter device concentrates and desalts proteins, antibodies, viruses from chromatography fractions, cell culture supernatants, fermentation broths, and biological fluids. It can also be used for exchanging buffers. The device can concentrate 70 ml down to 350 mgr>l in 25 minutes, with typical concentration factors between 50times> and 200times> and sample recoveries greater than 90%. The device features a "deadstop" that prevents samples from spinning to dryness. The device contains proprietary low-binding Ultracel regenerated cellulose membrane. co>B>I>Millipore Corp., /B>978-645-5476, www.millipore.com/I>/co>/t1>p> deeplink>http://www.millipore.com/proteinresearch/deeplink>rsphone>919786455476/rsphone>