Frequently Asked Questions

DNA Synthesis


Q. What is the advantage to using the CTGen ACTIVA™ Frits over bulk CPG?

A. Because the CPG is evenly distributed in the solid membrane frit, the synthesis reactions are more efficient. Our recommended protocols use 50% less chemicals than those for standard loose CPG. Besides the cost savings in chemicals and the time saved during synthesis, ACTIVA™ frits are clean, convenient and much easier to load into the synthesis plate.

Q. What is the primary difference between the ACTIVA™ Frits and the Standard EZ Frits?

A. ACTIVA™ Frits have activator covalently bound to the support so there is no need to add any during synthesis. This will not only save time during synthesis and cost in reagents, but will offer greater coupling effeciency and require less amidites.

Q. Do the ACTIVA™ Frits require different protocols than the Standard EZ frits?

A. Yes.  They are available in the product section of the website under All Protocols.

Q. Do ACTIVA™ Frits work with all major synthesizers?

A. With many.  They are recommended for gas pressure high-throughput synthesizers and extensively tested with BLP's Dr. Oligo and the ABI 3900.  CTGen offers protocols for these two machines at the following link:  All Protocols.

The ACTIVA™ Frits have been used successfully on custom made synthesizers which are hybrid vacuum/pressure driven machines.  Please email for general guidelines when working out your protocols.

Q. I am experiencing poor yields with the ACTIVA™ Frits. What do you suggest?

A. If you have followed the ACTIVA Product Manual carefully, click here to download this problem solving flowchart.

Q. I am experiencing good yields, but seeing poor analytical readings. What do you suggest?

A. Click here to download flowchart.

Q. Can ACTIVA™ Frits be used for RNA synthesis?

A. Yes.

Q. Is the bound activator cleaved during deprotection and will it affect my OD readings?

A. It does affect the OD reading. ACTIVA™ is a pyridine base activator, so it does absorp light and therefore increases the OD reading by 10-20% if you cleave THEN deprotect. If you cleave AND deprotect, your OD reading will be slightly higher.


Q. Is the bound activator effeciently removed by desalting or purification?

A. Yes.  ACTIVA™ is fully removed by desalting. There is no effect on final OD reading nor on oligo purity.


Q. I read on your website that there is less risk of in situ amidite deactivation by water when using ACTIVA™ Frits. Why is this?

A. An amidite is not activated as long as it does not reach the ACTIVA™  bound to the surface. The activator groups are close to the oligos. This explains why less amidites are needed and why coupling time is shorter.



Q. What is MOP™?

A. MOP™, or Manual Oligo Purification, is a CTGen patented method of high-throughput trityl-on oligo purification.  This system uses 5' DMT group resin hydrophobic interactions along with TT-stacking interactions, leading to better selectivity and more pure oligos. The end result, for oligos up to 90 mers in length, is a recovery yield and purity of 90% in very short processing time (10 to 15 minutes).  MOP™ columns are offered in smaller sizes than the competitors and will save you money in expensive buffer and create less waste for the environment.