hi all,

We had some issues with one of our EA-IRMS systems over the past 2 weeks whereby the lower (i.e. downstream) PTFE/silicone rings on the water trap are getting brittle and flake until there's not much left besides the PTFE. The upper one remains intact. This pushes unwanted stuff down the line and shows itself in higher m29 relative to m28 and consenquetly awful d15N data; d13C is not really affected.

We have been running GFF filters (fumed in HCl but oven dried afterwards) and a mix of soil & coastal sediment samples - nothing really new there.
We then get into the frantic routine that will be familiar to many - alternatingly baking out GC columns, swapping the GC column, replacing the Cu column and/or combustion column, replace connection between combustion and reduction column, run some standards, feeling pleased with yourself that the problem seems fixed, then notice it  just resurfaces after a few hours.

While we've had something similar before it has never lasted this long and I'm particularly keen to hear if anyone has a solid explanation (I'm ready to take alternative facts at this point) on what's eating the silicone and why only at the bottom of the H2O trap - and whether they have found a way to avoid this.

Thanks in advance for any hints

Signature Department of Earth & Environmental Sciences
KU Leuven

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