Chiral Separation of 1-Phenylethanol

[Roxanne42]

Hi there,

Been trying to develop a method to separate the enantiomers of 1-phenylethanol. If I run the same method as that in the test chromatogram that came with the column, my separation does not appear to be as great (close, but theirs has a distinct baseline in-between and mine seems to have a little more tailing) - first and second chromatograms in image below. Now if I alter the method to fully separate the two peaks, I end up with more tailing (third chromatogram). Any solution to this or I should just accept this tailing as a fact of life?



This is a brand new Astec/Supelco B-DM column (30 m x 0.25 mm x 0.12 um), equipped with a guard column. New inlet liner, septum, checked for leaks and already re-installed column. Tried *many* different ramps/flows (all with D=I=250 degC and split ratios varying between 30:1 to 100:1 (depending on my sample), a different sample solvent (peaks before those, like anisole and acetophenone, seem to come out more symmetrically).


Thanks!

Roxanne.

[chromatographer1]

I am not an expert in this field, but given the chemical nature of the chiral structures used to separate the components, which in this case are free alcohols, (can you spell hydrogen bonding) I doubt you will be able to eliminate the small amount of tailing you are presently seeing, especially if the coating was exposed to air at some point in time.

You may feel this is less than desirable, but in my jaded eyes it still looks pretty darn good. Of course, the given example may be from a column which is exceptionally good. Yours may pass the QA specs of the company but as we all know, not every pie is PERFECTLY round, and your column may be good enough to sell but not bad enough to reject.

If you are disappointed, show the column performance to the company and see if they will swap or replace the column.

Make certain of course, that it is not an installation, injection liner, or dirty detector issue causing the tailing.

And of course, you can ask for, and pay for, a column which meets exactly your requirements, but that might not be cheap, or possible.

best wishes,

Rod

[DSP007]

Dear Roxanne, desire to do better is always commendable, but not always useful. As we say "If have good - not wanted good. " You full (good) decided the task, what the was put before you .

[Peter Apps]

You have baseline separation, anything else is a waste of resolution. Be thankful.

The tailing is strange - it does not look like classical adsorptive activity, or like simple band broadening. If you really want to get it like the picture on the packet then try without the guard column.

Peter