20. Do I need a guard column?
In many cases, installing a guard column upstream of your analytical or semi-preparative column is a cost effective strategy. The purpose of a guard column is to protect the analytical or semi-preparative column from materials that would either adsorb on the column, or which would dissolve some of the column packing. Guard columns thus serve a sacrificial function; when a guard column is nearing the failure or breakthrough point, it can be discarded and replaced at a fraction of the cost of a new column. Knowing when to replace a guard column can be determined from observations about your chromatography. Loss in separation between peak maxima, increased peak broadening or tailing, or increased pressure drop in your system are all signals that a guard column may need to be replaced.
A guard column should contain the same packing as the analytical or semi-preparative column, and specific guard columns are available for all Daicel chiral columns. A guard column containing a different chiral stationary phase may actually diminish the separation. A non-specific guard column might absorb some sample or mobile phase impurities; however, it would degrade the separation by adding more volume to the sample flow path without increasing the separation.
The end fittings for a guard column are exactly the same as the main column. Therefore a short piece of narrow i.d. connecting tubing is needed between the guard column and main column. Guard columns for all H-series and R- or RH-series columns are cartridge type. A universal cartridge holder can be used for most of our analytical 5- and 3-micron column, together with a specific disposable cartridge containing the same packing as the main column. For small-diameter columns based on 3-micron materials, on-line frits should be added instead, in order to avoid deleterious increase of system volumes. For advice, please contact us: Chiral Technologies Europe (CTE), support@cte.daicel.com, Chiral Technologies, Inc. (CTI), questions@cti.daicel.com, or Daicel Chiral Technologies India (DCTI), chiral@chiral.daicel.com
