Chromatography Forum

I am experienceing peaks that are tailing. My supervisor and I have troubleshooted many of the common problems and have not found a solution. I have changed the inlet liner (making sure that it is clean and free of dirt, etc.). I have cleaned the actual injection port. I have changed to a different column and I still have tailing peaks. I have taken apart my FID to make sure it is clean and it is. I have check to make sure that I have make up gas sweeping the FID and I do. I have checked my split flow and it is ok. I am out of things to check. Please help with any ideas or other areas to check.

I am working with a Shimadzu GC-17A. I am using a Restek Stabilwax-DA column.

Thank you

What compounds are you analysing, and how much of each is there per peak ?

When you changed column, did both columns have the same stationary phase ?

Do all the peaks on the chromatogram tail equally.?

What is your injector temperature, detector temperature and column temperature programme ?

If you inject methane or lighter gas, does that peak tail ?, how long does it take to elute.

Is the tailing on the front or the back of the peak ?

It would be very helpful if you could post a chromatogram.

Peter

I am analyzing y-decanolactone, L-lactide, and glycodie.

Yes, both columns had the same stationary phase.

The tailing is so severe that the other peaks are not resolved. It does not even detect peaks at low concentrations.

Yes, methane was injected, it took approx. 0.25 minutes to elute.

The tailing is in the back.

I am not able to post a chromatogram, sorry.

Thanks for your help

Hi Athena

What about the other conditions that I asked about ? - it is nearly impossible to troubleshoot with incomplete information.

The methane hold up time is quite short - how long is your column, what is the internal diameter and film thickness ?

What is the split ratio ?.

What are the "other peaks" that you refer to ?

What are the samples dissolved in. Are they clean - i.e. no oils etc extracted from samples. Do you get the same tailing if you inject the pure compounds dissolved in clean solvent ?

Peter

I'm thinking small leak.
If you have a retention gap, press (glass) fittings or old ferrules, you might need to yank the column, retrim the ends and reinstall w/ fresh ferrules (put ferrule on, then trim). Start at the injector end and work your way south (dirty detectors don't cause tailing, that's usually a column (or installation thereof) problem.

I suspect you are using a capillary column from the details you have given us, and the cause of the problem is probably an incorrect installation of the column in the injection port. Be certain you have the proper length of column installed ahead of the ferrule of your injection port nut.

best wishes,

Rod

Hi Athena,

I think you have to change the septum at the inj.port. Did you try it?

bye,

avrc.

Hi,
have u tried over a new column ? I think Wax columns are so delicate and sensitive to the material u r injecting in them. They often get demaged. Have u repeated yr exercise using brand new column. if not i think u should, but make sure that yr new column is perfectly conditioned and absolutely ready for injection.

one more point i would like to know is have u developed this method or u r following an existing method.

if u have developed this method then tell me bout the other columns u have tried..ok ?

ok then
wish u all the best.

Regards,
Dhruvil