High base line in EI GC/MS

[panpicha]

I have a trouble with high baseline results. Do you know why this is happened?

[rb6banjo]

Without more details, you're not going to get very good answers. Does your MS give you a reasonable tune?

[panpicha]

yes I got a normal tune result.
I'm thinking about something in the GC/MS methods that make it high.
Do you have any advice about this?

[Don_Hilton]

This can be air, column bleed, a data acquisition parameter like a detection threshold. If you have a sample introduction system other than liquid injection with a syringe, it could be a malfunction with that injection system. If yoy have a split to some other components in the GC oven, it could be related to them. And, even though the good tune would suggest against it, it could be an electronic problem.

Given that each kind of instrument has different properties (and problems common to that instrument), what kind of instrument (make and model) and what version software are you using?

Waht is the instrument configuration?

What was the background level when all was well and what has happened to the instrument since. What is the background level now? What was the scan range then and what is it now?

How do air/water checks look?

Do you have a full scan of the background? Pictures really help - there are instructions for posting.