Chromatography Forum

Hello all,

Looking for insight regarding troubleshooting Endrin breakdown differences across instruments. Performed an experiment using same liners, same analytical method (including parameters) (randomized design). The instruments both have uECD detectors. Difference in Endrin breakdown between instruments is ~10% on average. If using same liners and same analytical method, ideas as to what else could be causing the system bias?

In my experience, Endrin typically breaks down heavily on the column. So it sounds to me like you have a column that could possibly need replacing.

I'll try that--I may actually switch columns between instruments to see if the performance follows the columns; either that or replace the column on the instrument with the high breakdown and see if comes down. Thanks

The steel body of the injection port can also contribute to endrin breakdown. Also the split vent line in the case of Agilent instruments.

Glass wool is also no friend to the endrin compounds.

i recently learned that inlets are, in fact, consumables. you can only clean them so many times before they are almost permanently active... bye bye endrin, aldrin, etc.

While inlets are considered consumables, they can also be cleaned. You will undoubtedly read in many places that using a wire brush will score the inside of the injection port, however I have been using brushes for years, and my endrin and DDT breakdown is generally <5%. As stated in a previous post, don't use glass wool in your liner, although this impacts endrin aldehyde far more critically than endrin ketone or endrin. Column type and film thickness will also play a role in degradation, as will age of the column. There are also several different liners you could choose from, with or without inert coatings. My advice is to start fresh with two new injection ports, and two new columns then re-test.

I also have good luck with cleaning. I remove the liner and swap for a clean one, then clean with alumina powder as you would a MS source.
The inlet swap takes about the same amount of time as brushing.