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- Posts: 7
- Joined: Tue Jun 24, 2014 7:38 pm
I use a Dionex DX-120 IC with a AERS500 (4 mm) conductivity suppressor and AS-14 (4 mm) column for anion determinations (F , Cl , NO2 , Br , NO3 , PO4 , SO4) with CO3/HCO3 as eluent.
Normally I calibrate with 7 stds at the start, I run about 80 samples of waters and in the end I pass my QC sample of recovery with very good results for years.
It recently started to happen that the QC sample began to get very high, so after that I re-injected the stds and observed that the sensitivity has increased for all anions by 40-50%
I thought it was a problem in the detector electronics inside the mainboard so we changed the board, but the problem persists.
Also note that the conductivity of mobile phase changes from the typical 17 uS to 20-25 uS.
Has anyone had a similar problem or can you think it may be happening?
Thanks and best regards
Flavio