By Anonymous on Thursday, November 20, 2003 - 04:33 am:
hi everybody,
since a few weeks i´m packing short 40x21mm columns with 4 mikron rp-material. due to short lifetime (<100 separations) i´ve regularly to unpack and repack my columns by slurry-packing. i experience shorter lifetime after each packing. is this because of mechanical stress during the previous packings? is there a limit of re-using rp-material??
thanks in advance
By Chris Pohl on Thursday, November 20, 2003 - 08:49 am:
What is the symptom defining the end of the column "lifetime"? High pressure? Loss of resolution? Loss of capacity?
By anon on Friday, November 21, 2003 - 12:42 am:
the symptoms are:
- high backpressure during slurry packing
- columnchecks before use show split peaks
- loss of retention
By Anonymous on Friday, November 21, 2003 - 11:22 am:
Dear Anonymous,
It sounds like the frits may be getting clogged during the packing. These probably need to be changed each time (or cleaned) you repack the guard column. You might want to check into using a larger particle size (i.e 10 micron) for the guard column also.
Regards,
Mark
By anon on Monday, November 24, 2003 - 01:37 am:
no, same results with new frits!
By Chris Pohl on Monday, November 24, 2003 - 12:23 pm:
I think the symptoms suggest bead fracture as a problem but it sounds like you also have a problem with either stationary phase loss or need to develop a cleaning protocol to remove highly retained contaminants that are accumulating. Have you tried cleanup with a potent solvent like THF? You can use sedimentation in a good dispersant solvent with decent viscosity (such as IPA)to remove bead fragments.