Hello, I am new to this forum so please excuse any informality.

I have been developing a related compound method which includes 6-chloro-4-phenyl-2-quinazolinecarboxaldehyde degredation peak. The only problem is that with all of the columns I have used, the only column that gives a symmetrical peak is the Nucleosil CN 250x4.6, 5 mc. From what people have told me cyano columns have a very short bench life and give many problems. I have found this to be very true.

I am currently running a gradient that is primarity pH 6.2 phospate buffer(90), methanol (8), and acetonitrile (2). The high pH is due to poor separation from the other degredants at lower pH's. My question are, please, has anybody had a similar experience with an aldehyde peak, where the tailing is very poor? Any suggestions of what type of column to try or mobile phase? Thank-you for your time, I really appreciate.

Sincerly,
Laura

There is no reason why a CN column is the only solution. If there are difficulties with peak shapes, I would always select one of the modern RP packings with an incorporated polar group. I would be surprised if such a packing does not solve the problem.

Thank-you Mr.Uwe Neue. I have seen some of your work (in journals) and answers you have given to others. I appreciate your time and help.

Would a phenyl column or a fluoro-phenyl column be a good choice to start with?

I have found that phenyl columns can often give results similar to those of CN columns. Also, it has been my experience that not all CN columns are equally durable. The CN column that I am currently using (Keystone Scientific Betasil) has lasted much longer that the past two CN columns that I have had (Phenomenex Spherisorb and PhaseSep).

Thank-you for your help! I am actually using the Keystone Nucleosil and now I am trying the Betasil. I'm glad to hear you have had a better experience with the Betasil. Good luck!

I am a bit conservative on this. I would start anything with a C18 or C8, and for something that has peak shape difficulties, I would exclusively use a good packing with an incorporated polar group. This gives me already two very good choices in selectivity. Everything else is only a third choice, if I can't get the primary choices to work. On the other hand, I have only rarely seen the need to use something different.