Hi René

I had same question months/year ago but was hard to find information. What I found was that the critical micelle concentration (CMC)  and micelle microviscosity for these two cationic surfactants, have been studied through Electron Spin Resonance technique and the main difference seems that self-aggregation behaviour seems to be more marked and cooperative for CTAB than for DTAB thanks to the higher number of carbon atoms in CTAB tail. It occurs around 1 mM for CTAB and 14 mM for DTAB. However this does not reply to your question. Mixture of them is recommended for dirty samples apparently.

As their carbon chains are different (12 and 16), I am wondering as their charge is positive if their zeta potential is also different and if the target proteins they bind could be different, therefore having a mixture could be the best indeed to get cleaner DNA. In the group, we use CTAB and it worked quite well however but working with algae…

Thank you Brigitte, that sounds like a good possible answer.

Hi René, as Brigitte mentioned the difference is only in the hydrophobic chain length. This affects the Hydrophilic-lipophilic balance which can have quite an effect, surface science is governed by small forces will additively become large. The hydrophobic chain length has an effect on the lyses of membranes and freeing DNA. Exactly how and in which direction is difficult to tell in a complicated system and trial and error is the best bet I suppose. And there are many methods described see https://www.envismadrasuniv.org/DNA%20Isolation%20Procedures.pdf as an example.

Regards

Ragnar