peak fronting

<p>Taking an existing UPLC method, and only replacing the existing column and guard column, with a new column/guard column (same type, BEH C18, 2.1x50), all else being the same, we are seeing significant peak fronting. Almost as if the peak is starting to split. Mobile phase, sample diluent, temp, etc... are all the same as before. It's a Waters column, PN 186002350. This is happening in standards right now, no samples (analytes) have been run on this new column. Is it possible it's a bad column? We are limited in quantity with columns to troubleshoot with others. </p><p></p><p>Any suggestions?</p><p></p><p>Thanks,
Grant </p>


  • Dear Harringg,

    It is most likely a bad fitting at the column inlet or outlet. Fitting become worn or are not seated properly. Please see the attached power point titled "split peaks" it contains experts from several sources. It shows several examples of poor chromatography resulting from poor fittings or other issues. I hope that you find it useful.


  • Thanks for the information. I'll pass it along to the UPLC operator, and reply back. From what I've observed here in the lab, all mobile phase, s/w solvents, sample diluent, injection volume, etc... is correct. The only thing left would be either a fitting or a bad column. Putting the "old" column on the peak spliting/fronting went away. Maybe the new column isn't seating properly.