High Affinity Purification (HAP) is a patented, novel purification method for custom oligos. DMT-ON-Oligo in the crude oligo mixture is first selectively absorbed on a high affinity resin in HAP column while incomplete oligos pass through. Final oligo is produced by removing the protection group of DMT under mild acidic conditions. HAP method provides two major advantages, high purity superior to De-Salted method (>98%), and low cost comparable to PAGE or HPLC methods. Oligos produced by the HAP method has such high purity that they can be directly used for any downstream experiments such as PCR, DNA Sequencing, Gene Synthesis, and Mutagenesis. At present, the most economic method to produce oligos is the De-Salted method, which however, yields products poor in purity. For example, the purity of 20-mer, 40-mer and 60-mer is approximately 68%, 45% and 30% respectively. This is calculated based on the 4 steps in DNA synthesis: De-DMT, Coupling, Oxidation and Capping. The average yield of each cycle is about 98%. The purity of 20-mer is therefore (0.98)20-1 = 68%; of 40-mer = (0.98)40-1 = 45%; and of 60-mer = (0.98)60-1 = 30%. Most laboratories use De-Salted oligos despite of their inferior purity because higher quality oligos produced by alternative methods such as PAGE, HPLC, and OPC are too costly. HAP presents the perfect alternative for high purity oligos at lowest prices. In fact, price is even lower than those of De-Salted method in some cases.
When ordering oligos: Remember that the scale of synthesis (25 nmol, 100 nmol, etc.), refers to the starting material used to synthesized the oligo, NOT the FINAL yield. Oligo length, sequence, GC content and coupling efficiencies can vary the final nmole yield post-synthesis. Different purification methods will also alter the final product yield. Bio Basic guarantees the final yield of each oligo nucleotide as a FIXED final yield in OD units.