Our 7900 ICP-MS is showing high oxides/doubly charged upon start-up. Running the standard lens tune, plasma correction, and resolution/axis typically fixes the issue and brings the ratios down to something reasonable.
To illustrate, the full-suite of start-up procedures was run yesterday (our routine practice, performed monthly) which yielded oxide/DC at 1.36/1.19%, and then several standards and a few drinking water samples were run. Today, just running the performance report (and no other start-up procedures) yielded oxide/DC at 6.29 and 1507.06%. Running the standard lens tune, plasma correction, and resolution/axis brought it back down to 1.37 and 1.27%.
This is atypical, and has only been observed in the recent past. I'm wondering if this could be indicative of a hardware issue?