Easiest way to clean fatty acids out of column without cutting.

We do not test fatty acids, but get bouts of strong fatty acids being caught up in the column.  Are there any easy cleaning methods that would prevent constant cutting of the column?

  • Use a piece, maybe 250cm or 500cm, of uncoated fused silica the same i.d. as your column in the inlet connected to an Ultimate Union for GC | Agilent and then to the analytical column. When the uncoated piece is contaminated, replace it with a new piece that's the same length.  It only costs you two new ferrules every time and the retention times don't change much, if at all. You can make up a number of the precolumn/retention gap pieces and have them with the ultimetal ferrule for the ultimate union already swaged on and ready to go.  

    A much more complicated but automated way is to get your system setup for backflush with the necessary PSD/Aux EPC channel and a Purged Ultimate Union (PUU).  A typical setup is a 5 meter column 1 from the inlet to the PUU and a 30 meter column 2 from the PUU to the MS.  At sample injection, Column 1 flow is 1.0 ml/min and Column 2 flow is 1.2 ml/min.  After your peaks of interest have gone past the PUU but the fatty acids are still on Column 1, the system changes the flow to be Column 1 minus 3 ml/min and Column 2 still at 1.2 ml/min into the MS. Column 1 is backflushed to the injection port and the residue goes out the split vent leaving Column 1 cleaned up and ready for the next injection.   Once the hardware is installed and configured properly this concurrent backflush methodology is simple to implement.    It's also easy to replace Column 1 as you do not need to vent the MS.  

    CFT Purged Union Brochure.pdf (agilent.com)

    Split, Switch or Backflush - Complete guide to Capillary Flow Technology (CFT) (on24.com) Is a recorded webinar that should help.

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