Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 25 bp to 20 kb. Negatively charged DNA (and RNA) migrates through the pores of agarose gel towards the positively charged end of the gel when an electrical field is applied. Because DNA has a uniform mass/charge ratio, DNA molecules are separated by size within an agarose gel in a pattern such that the distance traveled is inversely proportional to the log of its molecular weight. After separation, the DNA molecules can be visualized under uv light (or Blue LED light) after staining with an appropriate dye. Samples are run alongside DNA ladders or markers to identify the approximate size of a molecule.
There are a number of buffers used for agarose electrophoresis. The most common being: tris acetate EDTA (TAE) and Tris/Borate/EDTA (TBE). TAE has the lowest buffering capacity but provides the best resolution for larger DNA.

Different types of agarose qualities optimized for specific applications are available at Tiaris Biosciences. Find the best electrophoresis reagents in our product directory.