Can anyone recommend an HPLC column that is fairly stable at pH values of 10-12? I currently use 150 x 2 mm LUNA C18(2) columns from Phenomenex for the application, but they only last a few weeks to a month before failing (= approx 500 hrs use). I can't substitute a lower pH mobile phase for the application, nor can I use polymeric columns because the plate count is too low to get the resolution I need. So, basically, I am looking for a column with a plate count similar to that given by 150 x 2 mm x 5 micron silica but alkaline stable. Any suggestions - even other manufacturers (e.g. Waters) that may produce proprietary columns?

Try Waters XTerra or Agilent Zorbax Extend columns. Both can be used at pH <12.

I can attest to the Xterra's stability at pH of 11 and above. Waters has it in 150 x 2.1, 5um.

ZirChrom's Diamondbond-C18 columns are stable at high pH, but they also often (but not always) require an elevated column temperature.

Also me, I have used the Agilent Extend column with success, they are stable for long time and reproducible from batch to batch, I am using it for basic peptides QC on LC-ESI-MS

Hello Tony,
sometimes problems can be solved when changing to another column, but in many cases the column is not the real problem. Please tell us more about your buffer system, and the other chromatographic conditions. For example, if you use a borate buffer, no matter what column you are using, lifetime will be short. Glycine as an alternative will increase lifetime of your column. Column temperature is also very critical, when using high pH values. What kind of polymeric RP-columns did you tested for your application (porous or/and nonporous resins?). Also sample matrix is important. It is possible you will get longer lifetime while changing your column, than you had good luck. But it is also possible that you will run into other problems. Good luck. Gerhard

I'll add a note of hard-nosed bottom line realism here:
how much are you spending on columns for this method, and how much will it cost you to modify it? (i.e., is this trip worthwhile?)

We used Luna C8(2) at pH 11.5 for at least 100 injections - without any visible changes in performance (Resolution, N , etc).

Dr.A.Weisman
Chemagis Ltd.
Israel

One of the old tricks is to add a silica column before the autosampler to saturate the mobile phase with silica. This may be the most cost efficient solution or the solution that may allow you to maintain your separation.