AB/Sciex API 3000. What kind of noise?

[Alp]

Hi all,

I am looking for some feedback. I was running a Q1 scan the other day and noticed my baseline noise was between 5x10E4 and 1x10E5. This was 10 scans MCA mode, so if I did not run MCA mode the noise would be 1/10th or about 5x10E3 to 1x10E4 let's say.
Oh, and I was in negative ion mode, -4500 volts.
I thought this was a bit high. I have a much older instrument that gives me almost 1/10th this noise. Would this be considered normal on an API 3000?

Mobile phase was 65/35 MeOH/5mM AmAc aq. and I had a split so I was probably spraying in about 40 -50 uL/min, ionspray.
Q1 scan 50 to 500 AMU.

Thanks

Alp

[bisnettrj2]

Any particular pattern to the noise? Any masses that were dominant?

[Alp]

A few large peaks, but I am more interested in the baseline noise level. When zoomed in enough it looks like a peak every 2 AMU or so and when zoomed out resembles grass. You all know what I mean.

iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii noise .