I am a little wary of the idea of venting a system to clean these parts and
then relying on the tune created prior to the vent. I have noted that it
usually looks OK anyway. It is still not my own practice. It does get to
some of the places where the ultramark may be hiding. I couldn't say if the
ultramark in these "post-source" areas are capable of being ionized and
detected however. I usually assume that pre- and in-source locations of
contamination CAN lead to "background" and anything anywhere else CAN ONLY
degrade ion-optic performance. This degradation mechanism would be produced
by insulation of ion optic components produced by organic and inorganic
deposits. The insulation would reduce signal and is one big reason that
mass specs need cleaning/tuning. But...
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: Paul Jedrzejewski <pjedrzej@lynx.dac.neu.edu>
To: Recipients of ABRF List <abrf@aecom.yu.edu>
Date: Thursday, November 11, 1999 3:15 PM
Subject: LCQ Calibration
>Hi Tom,
>
>Welcome to LCQ user's club. It is a MAJOR pain; this ultramark stuff.
>
>I will second what Matt and Dan have already stated. Most importantly is
>to have a dedicated pluming for tuning together with the ESI probe
>elements which come in contact with this solution. It will save tons of
>time. I keep this stuff in a separate box labeled as such, so that it
>does not get mixed with other hardware.
>
>Simplifying your source (ala nanospray) is a good idea. It deposits less
>of this stuff on the heated capillary and beyond, thus cleaning is much
>faster. I have used fast flow nanospray needles loaded with 10uL (huge!)
>tuning solution. If you don't have nanospray source, I also use a
>simplified home-built source (a holder and one-piece fused silica line
>(50um ID) to the syringe) which can be operated at 100's nL/min, thus
>limiting the contamination.
>
>A word about cleaning. After using the std setup for tuning (and also
>using the nano setup but not as bad), I found it necessary to clean the
>heated capillary, lens, and skimmer.
>These parts were washed with MeOH/Hexane and ultrasonicated in MeOH,
>where as, the heated capillary was washed by pushing/pulling some of the
>same solution. Once all was assembled, I would bake the source at 250
>overnight and pray.
>
>Good luck,
>Paul
>
>
>
>>To: Recipients of ABRF List <abrf@aecom.yu.edu>
>>cc:
>>Subject: LCQ Calibration
>>
>>A question for those of you who have LCQ mass spectrometers. Has anyone
>devised
>>a cleaner calibration mixture for the LCQ--one not using Ultramark? We are
>>finding that we spending a significant amount of time cleaning the
>instrument
>>after running the calibration mixture as prescribed by the vendor.
>>
>>Thanks in advance,
>>Tom McClure
>>-------------------------------------------------------
>>
>>
>>
>
>
>
>________________________________________________________________
>Paul T. Jedrzejewski, Ph.D.
>Barnett Institute
>341 Mugar Bldg.
>Northeastern University
>360 Huntington Ave.
>Boston, MA 02115
>
>phone: 617.373.2857
>fax: 617.373.2855 http://www.barnett.neu.edu
>__________________________________________________________________
>
>