During the purification step the crude products from synthesis are refined to oligonucleotides with high or extreme purities, depending on the requirement from the customer. For this procedure we use HPLC instruments and use Anion Exchange (AIE) or/and Reversed Phase (RP) technologies to separate the target oligonucleotide from the shorter oligonucleotide fragments remaining from the synthesis. 

The AIE technology separates oligonucleotides by net charge, whereas the RP technology principally separates oligonucleotides by hydrophobicity. The method used depends on the nature of the product, different specifications and field of application. All methods are developed at SGS DNA and are proprietary.

Each product is extensively fractionated during the purification and the fractions are analyzed by our Quality Control. Only the fractions that meet the specification for the final purity will proceed to the next step and be a part of the final product. After the purification the product is desalted in order to remove buffer residues from the HPLC run.

The  HPLC columns used for pruification are manufactured at SGS DNA. For IVD/ASR products we use dedicated HPLC columns.