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silylating reagent through DB-5 column

pstaunton

hi,

having an issue where a peak of interest (which has a -OH group) is starting to tail badly after a number of runs. as all other peaks are not affected this has to be an activity issue?

I have tried inert columns, inert liners, inert gold seals but the problem will eventually arise very quickly. column is DB-5 with a guard column. 

I'm curious to know whether the injection of a silylating reagent through the column would improve the situation? I understand it will react with any active hydrogens (like -OH groups).  I'm sure it make more sense to add the reagent to the sample but this would involve revalidation work which is not feasible. my thinking is that there are contaminants in the sample that are interacting with the polar analyte and causing peak tailing, as the sample im afraid is only diluted with acetonitrile and probably contains alot of semi-volatile junk?

Can a silylating reagent be run through a GC column and "clean" the column of semi-volatile contaminants? 

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  • +1

    Hi pstaunton,

    injecting a pure silylating reagent onto any siloxane-based column would destroy the column immediately as it would break the siloxane bonds in the phase.

    Try conditioning the column as described in the column manual first. You can also use a replaceable retention gap with apolar deactivation instead of the EasyGuard, polar impurities should stick to the retention gap first. Replace as often as necessary.

    Regards,

    Norbert

  • 0 in reply to Dr. Know

    ok thanks for the reply. In terms of the guard columns available on the Agilent website I am not sure which to choose based on apolar deactivation? I see there is medium polar/methyl deactivated type retention gaps. how do you choose which is the best option? Also what would be the optimum length for guard column if your main column is 30m x 0.53mm?

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