Hello, I hope this finds you well,
The past year, I have been using a method I had inherited for use on two 7800 instruments and am now working on optimizing them. When I tune with low matrix, I get good counts and precision on both instruments, whether I use He gas or not. However, I am looking to use HMI plasma mode (we have about 0.5% TDS in our samples) and I am trying to improve the low counts and precision I see in HMI, which are close to 300 counts and 6% RSD (see my two attached reports for low-matrix and HMI).
I have tried purging our helium line and have installed new cones, skimmer, nebulizer, peri-pump tubes, and do not notice any changes.
For reference, I use nickel skimmer cone and a nickel-tipped copper cone with a MicroMist nebulizer. One of the instruments has the AVS (ISIS 3) installed, and shows a slight decrease in mass 205, but no other significant differences. I use 1 ppb tune solution for the instrument without the AVS installed, and 10 ppm for the other instrument.
I have attached tune reports for the same method in low matrix mode and HMI for comparison (on the instrument with AVS).
Additionally, I have an unrelated question; If I use narrow peak helium in conjunction with standard helium (identical tune parameters), should I add stabilization time between the two modes? If so, how long would it need to be?
If there is anything that you could suggest or improvements that I can make, anything would be appreciated!
Thanks a lot and have a wonderful day!
