Aufreinigung und Aufkonzentration

Purification or concentration of DNA fragments or PCR products involves separation of DNA from in vitro reaction components or from agarose gel slices. In many cases, after a PCR amplification or restriction enzyme digestion, the reaction components include primers, proteins and salts that may inhibit performance in subsequent analyses. 

Fragment DNA clean-up can improve efficiency in downstream applications. For example,  non-specific PCR products and primer-dimers in an amplification reaction can compete for ligation with the desired PCR product in subsequent T-vector cloning, resulting in low frequency of positive clones.

In Sanger sequencing, certain reaction components will interfere with data collection if not removed before data analysis. Buffer salts give rise to aberrant electrophoretic migration, and unincorporated dye-labeled terminators and related species interfere with the legitimate signal from sequencing extension products. 

Like other DNA and RNA purification systems, products designed to purify fragments or concentrate DNA or RNA typically involve immobilization of the nucleic acid on silica or cellulose incorporated into membranes, resins or magnetic beads, followed by washing and elution steps.