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- Posts: 3
- Joined: Fri May 09, 2014 1:35 pm
I am new to IC, and working for a small environmental company. I was left with 2 Dionex-120 systems, and no real instruction on how to maintain or troubleshoot these systems. The work being done is simple anions analysis (F, CL, NO2, Br, NO3, PO4, SO4) in the standard matrices, using carb/bicarb eluent.
Equipment: Dionex -120/AS40 autosampler, AERS 500 4mm Supressor (Brand New), Dionex IonPac AS-14/AG 14 250/4mm
Issue: I have started seeing reductions in concentrations on QC samples. The reductions started with PO4, which is getting a ~70% return. The Calibrations are also failing for PO4. Within the past week, I have seen reductions in almost all analytes, with 80% recoveries on QC samples. The difference is the calibration curves for the other 6 analytes are excellent. I do run soil samples on one of the 2 instruments. I have followed all the cleaning procedures outlined in the manuals for the Dionex column, and have almost rebuilt both systems over the past 6 months. My retention times have shifted, but not drastically, and not out of my 10% window used for RT studies. The columns are not new, and have had quite a few samples run on them, but nothing out of the ordinary based on past run logs.
I am wondering what can be done to bring my recoveries back, and what can be done to prevent this from happening in the future.
I appreciate any response, this can be frustrating for a person with a minimal chemistry background.