Chromatography Forum

Good afternoon,

The sensitivity on one of our GC-MS is ~10x lower than the others. We are analyzing bde/bfrs using NCI. I decided to run an auto.tune and noticed that the entlens value is 0... I've tried changing the value through manual tune but it keeps going back to 0. I checked the wire connection for entlens inside the ms and it seems fine. I was wondering if anything else would give you 0 for entlens, other than no power to it?

Thanks

Sylvain

I hate wasting time knowing that it's probably something stupid

finally tune report looks normal... ended up changing tip seal, repeller insulator and filament (all 3 had scene better days). Now my tune report looks great.

Glad you got it fixed. What instrument do you have?

I'm running a 6890 (by agilent) with a 5973 in NCI mode.

I'm still not convinced that eveything's good though. The prob with this instrument is that there's too many user's

here's a general question pertaining to entlens value? what would make entlens' value vary from 4 to 30 in a short lapse of time? The source is clean.

Thanks

I cannot say what would cause it, other than a dirty source.

I will note that currently about half of the MSs I work with have the ENTLENS value as 0, while the others vary widely (5-22). We had an issue with Argon contamination over the last week, and since then half of the ENTLENS values dropped to zero.

wow have you noticed any changes due to the fluctuation in entlens value?

Thanks for the feedback, it helps

I haven't noticed a fluctuation in anything, especially sensitivity. On another, perhaps related, note; I had started using stune instead of atune for the instruments that are now exhibiting the ENTLENS=0 behavior.

I assume this prob was related to my other post... once i cleaned the source my entry lense value went back up to 28ish.

Thank you all

Cheers