This procedure is effective only when the 5' dimethyloxytrityl protecting group is left on the oligo. Each OPC cartridge (ABI part # 400771) can bind approximately 5 ODU of trityl-on oligo. If you wish to use this purification procedure please be sure to indicate on your order that the 5' trityl group is to remain on (simply select "TRITYL ON"). Otherwise, the final trityl group will be removed from the 5' terminus and this procedure cannot be used. The trityl group is highly hydrophobic, and will act as a "handle" when passed through the cartridge. If the length of the oligo to be purified exceeds 40 nucleotides in length two additional washes (steps 8 and 9) are recommended.

Procedure:

1. Pass 5mL of acetonitrile through the OPC (ABI part # 400771) to waste.
2. Pass 5mL of 2M Triethylamine Acetate (TEAA, ABI part # 400613) through the OPC to waste
3. Dilute the oligonucleotide ammonia deprotection solution with an equal volume of water, e.g.; 1mL of each. With a loading solution of 50% water/ammonia, each OPC cartridge can bind approximately 5 ODU of trityl-on oligo. Pass the diluted solution through the OPC at a rate of about 1 drop per second. Collect the eluate and pass it through a second time.
4. Pass 5mL of dilute ammonia^* through the OPC to waste.
5. Pass 10mL of water through the OPC to waste.
6. Fill the syringe barrel with 5mL 2% trifluoroacetic acid (TFA) in water and pass a portion through the OPC to waste. Let stand 3-5 minutes before passing the remainder through to waste.
7. Pass 10mL of water through the OPC to waste.
8. Pass 5mL of dilute ammonia through the OPC to waste.
9. Pass 5mL of water through the OPC to waste.
10. Elute drop-by-drop with 1mL of 20% Acetonitrile (ABI part # 400314) in water and collect the purified oligonucleotide in a 1.5mL Eppendorf vial.