A Z-Guard can provide many advantages whether it is used as a retention gap for volatile compounds or as a guard column to catch higher molecular weight contaminants and extend column lifetime. The key to getting the best performance from any attached guard column lies in the installation. A proper installation will ensure that there is no added dead space or chance for leaks.
Here are some general instructions on how to install a Z-Guard:
Properly cut both column (guard column and analytical column) ends squarely (see below for illustration).
Inspect the cut to verify a good cut. This is important. A poor cut is more likely to leak (see below for illustration).
(optional) Dip both column ends in Methanol or Acetone solvent. Alternatively, wipe gently with lint free cloth permeated with solvent. This may help swell the polyimide to aid in sealing.
(optional) To help secure the column, a bead of polyimide resin can be placed either at the opening of the fitting after the column has been installed or ~0.5 cm from the tip of the column before the column end is placed into the fitting. The easiest method of resin application is to dip a tooth pick into the resin and gently apply a ring of resin to the column.
One end at a time, firmly press the end of each column into the opening in the Press- Tight® fitting. A complete and uniform ring should be visible where the polyimide of the column is in contact with the glass from the fitting. If not, remove the column, re-cut the column, and re-install.
If resin was used to help secure the column ends, a curing step is recommended here the column (with carrier gas) is slowly heated (2-5 °C/min) from room temperature to 180 °C. Let the polyimide cure for 5-10 minutes at this temperature.