Changes in Electron Multiplier Voltage

[Ostravaczech]

Hello,
Autotune (Agilent 7000C, 9 months old) shows drastic increase in electron multiplier voltage. During this week, it went from around 1500 to 2100V. Also, the emission current as well as the electron energy is changing from one tune to another. I was running NH3 PCI so I vented the MS and popped in the EI - same thing (previous autotune was around 1500, today it was 2059 Volts). I will be calling Agilent but in the meantime - any suggestions?

[James_Ball]

I have not done CI on our 7000 but with EI ours does not change the Electron Energy when doing an autotune, it stays at 70Ev constant, and normally it doesn't change the emission current either, normally set to 35 as default but I run it at 25 normally.

Try setting the volts and current to 70 and 35 then run the Gain Curve on the Detector Tab of manual tune and see what the multiplier setting is on the EI source.