DNA Purification Methods
Ultrafiltration (UF) is a membrane separation technique used to separate extremely small particles and dissolved molecules in fluids. The primary basis for separation is molecular size, although other factors such as molecule shape and charge can also play a role. Compared to non-membrane processes, ultrafiltration is gentle, fast, and relatively inexpensive. Methods for purifying nucleic acids using the Pall Nanosep® device, which contains a membrane operating by molecular weight size exclusion, are well established and covered in the application guide, “Nanosep Centrifugal Devices Protocols for Use.” The methods described allow rapid, simple recovery of high yields of purified DNA. The same technology is also available in multi-well plate formats for parallel processing of biological samples requiring purification.
These methods use solvents such as chloroform/phenol to solubilize cellular material and partition the DNA for subsequent purification, e.g., using density gradient centrifugation. The limitation of this method is the disposal issue created by the extraction solvents used and the purity and yield of the DNA recovered.