Here is a ref from the STMS archives in response to a HIGH mass background
problem.
http://www.chemistry.gatech.edu/stms/iontrap2.txt
and here are my $0.02:
I have seen some the Protana tips give high background at low mass in my
hands. Protana may not have this problem and it could have been a batch or
my own fault, but...The New Objective tips were lower background. I also
found that the solvent for the conductive "paint" I used to provide a
conductive path produced considerable(!) background at times at low mass.
Switching to New Objective and reducing the amount of paint and allowing it
to dry before use, reduced the background to useable but NOT non-zero
levels. I am not a day to day user of this technique however and my
comments may be those of a novice. Maybe you can do a summary post of
answers when you get a good handle on what is going on. I know I'd like to
hear!
Matt Sweeney
mattsweeney@earthlink.net
Mass Spec Consulting
Training/Operations/Consulting/Method Development
LC/MS Pharmacokinetics, Peptides, Proteins, Metabolism,
Maintenance Classes, Specialist in Finnigan Equipment and Software
-----Original Message-----
From: Denise A. Meagher <wenzed@rockvax.rockefeller.edu>
To: Recipients of ABRF List <abrf@aecom.yu.edu>
Date: Thursday, November 18, 1999 10:25 AM
Subject: LCQ contamination
>
>Hello all,
>
>We're seeing lower MW peaks on our LCQ in the range
>200-500 Da even when spraying a blank. Does anyone
>else have this problem. The largest of the peaks
>seen are at 254 Da and 299 Da. Our instrument is
>equipped with a nanospray.
>
>Thanks for any help.
>
>Denise
>
>Denise A. Meagher
>Protein Chemisty Coordinator
>Protein/DNA Technology Center
>The Rockefeller University
>1230 York Avenue, Box 105
>New York, NY 10021
>
>Phone: 1-212-327-7525
>FAX: 1-212-327-8620
>email: wenzed@rockvax.rockefeller.edu
>
>
>