20 years running purge and trap GCMS and I am stumped

[James_Ball]

Having a weird issue as late. Using a Tekmar Stratum and Aquatek 70.
Every once in a while our CCS's last 4 cpds will be about 30% of all the rest.
Yesterday I cleaned the sample mount, flushed the tubing from the exit of the "water trap", and installed a clean sparge vessel and a new VOcarb 3000 trap.
Ran calibration curve. First 2 standards were fine, the remaining stds had the late eluters off by ! 70% ( the 2 tri chloro benzenes, hexachlorocyclopentadiene, and naphthalene).

I did 4 direct injections in a row with all cpds consistent in all injections.

Question for James, have you been able to clean your "dry trap"? Do you remove it, or flush in in place?

The traps in the Encon are simply and empty trap with the silcosteel coating. I have used methanol before and even used a pipe cleaner or for really bad contamination pulled enough cotton off the tip of a swab and forced it through the tube. It is surprising how dirty it can be when it comes out the other end.

This usually brings it back some, but often it is best to just replace the trap completely. Lowering the water trap bake temperature seems to have worked better than anything though for making them last longer.

[Bigbear]

Update
So I installed the injection port into my Stratum ( should have done this earlier) only to find the loss was between the Stratum exit and the GC inlet. I had changed the transfer line tubing, so installed a clean injection port, new liner and seal, and clipped the column. Problem solved. Maybe the clean injection port was over kill.

BTW the Stratum "dry trap" is the same as on the Encon.