In PAGE Purification method, oligonucleotides are loaded on a polyacrylamide gel with the best appropriated percentage of acrylamide to purify the desired full-length oligonucleotide. The major product obtained is the slowest migrating band, which is excised out of the gel under low-intensity UV shadowing. The oligonucleotide is eluted from the gel slice then precipitated with ethanol, quantified and packaged.
In most cases, full-length (n) oligonucleotide can be separated from oligonucleotides only one base shorter (n-1). Due to its excellent resolution, denaturing acrylamide gel electrophoresis provides a higher degree of purity than HPLC (purity level up to 90 % can be achieved) but yield obtained is lower than other purification techniques. Nevertheless PAGE is the best suitable method to purify oligonucleotides longer than 80 bases or intended for Gel-shift assays.