For the past month we have experienced off/on again issues with the sensitivity of our Ultivo MS. It orginally began when the MS would complete autotune saying that either the nebulizer was damaged or that it had issues seeing the voltage signal. At this point we had no peaks. I replaced the capillary ion injector and then saw peaks. We also replaced our column and its guard column. A couple of runs later the error message about spray stability popped up and even though the nebulizer needle visibly looked fine, I ended up replacing it as well. (This is the first time I replaced the needle but I believe it was done correctly).
I ran my curve two times and both runs had wonderful signal and passed beautifully. I also did regular maintenance and replaced the PTFE frits in both pump heads. My next run after that my calibration curve failed miserably (this curve was made in batches at the same time as the previous curve I have been using). Most of the standards were failing in the curve. The fit of the curve is no longer linear and follows a quadratic fit. I reprepped a new curve and it has the same issue. The signal area has dramatically dropped and the line of best fit follows more of a quadratic fit.
Has anyone experienced this before or have any suggestons/thoughts?
Any help would be greatly appreciated. Thanks