Chromatography Forum

Hello,

I need help from Thermo ISQ users. I am using a Thermo Scientific ISQ. The default tune for the 69 ion is 20 million counts. This cause the multiplier to run at a high voltage and I have to change two multipliers in a year.

I have no idea why the default setting is so high. It seems to me that the abundance have nothing to do with signal to noise. I am now tuning the 69 ion down to 9 million counts, which cause the gain to set to 1E5 instead of around 3E5, and I still have about the same sensitivity.

I don't want to miss anything, so if you are a Thermo ISQ user, and you know of any reason why I should set my gain higher, please let me know.

Thank you so much.

chromuser2000

I'm not an ISQ user (we do have DSQ and TSQ)
What I understood from a chat with a service engineer there are 2 way's of tuning a ISQ. One is tuning m/z to a certain intensity (the one you are discribing) the other one is more simular to a DSQ or TSQ tune and is measuring the intensitity of a standard amout of PFTBE.
You might contact Thermo to explain the 2 way's of tuning.

ps: keep in mind that it was a simple chat, we dit not discuss the fundamentals, so I might not be 100% right in this.