What is PCR purification.PCR Purification Protocol is designed to purify double stranded DNA fragments from PCR and other enzymatic reactions. Fragments from 100bp to 10kb are purified from primers, nucleotides, polymerases and salts using QIAquick spin columns in a microcentrifuge. Even if distinct bands of the expected size are observed, primer dimers should be removed by PCR purification method. In the absence of the purification, the proofreading activity of DNA polymerase will degrade the PCR fragments or remove the 3' terminal deoxyadenosine from the vector during ligation reaction.