Chromatography Forum

I've been told that one should cut their GC column every now and then. How often should this be done and how much should one cut off (30 m column)? Is this also a recommended practice for chiral columns or just standard ones?

Agilent appears to sell a few items to effect the cutting of columns - which would you recommend?


Thanks,

Trishia.

GC columns collect at their inlet, particles from septa, decomposition products from the thermal evaporation of injected material, and oxidation of the phase from trace amounts of oxygen which enter the system.

Cutting 6 inches to 40 inches of column every so often (empirical evaluation is important here, your results may vary) will affect analyses very little (plate numbers decline by the square root of 2, a column half as long still gives 70% of the resolution, so a 30m trimmed thrice to a 27m, doesn't make that much difference).

Yet by trimming the column, you may be removing active sites which can ruin your analysis.

Try it on occasion and see if things improve. If not then don't.

best wishes,

Rod

This approach should not be used often. Most non voaltile sample matrices should stay in the liner (unless you are doing on-column injection). You can change or clean the liner. If the column get dirty quickly, you may look at the sample cleanup part. Another way is to add a retention gap (a capillary without coating) to the front of the analytical column.

It is worthwhile to remove the interference before injecting the sample to GC.