That IS a hassle.
Here are my tips.
1)I have utilized a separate syringe and transfer silica line dedicated for
ultramark. That helps.
2)The ESI probe is another source of contamination. For this I have used an
acn:meoh 1:1 mix. Mehdi Moini's (first ref on esi ultramark in jams) paper
mentions this mix. Perhaps there are better ones. I have another
syringe/transfer line for the acn:meoh which I attach to the grounding union
and pump several syringe full while the source is on. Then I attach the
solution to the sheath liquid input and pump some more through here. This
is because some ultramark lurks in the inter silica/needle space where the
sheath liquid passes. Then I attach the N2 from the aux gas line to the
sheath liquid input and blow that area DRY!!!. Then if you want you go to
step 3) . Or rinse the sample input once more with the 1:1 and then go.
But first I turn off the ESI and do the next step. Another thing is to
replace the ESI silica after a tune. I always like to have giant rolls of
that stuff around anyway. Polymicro Technologies sells it among others.
Pull the silica out the needle end though.
3)I have found that the peek sleeve around the heated cap. is one other
source for contamination (in addition to the spray shield). I direct the
acn:meoh at the crannies around the peek sleeve and at the shield itself. I
remove the ESI probe and then do this for better access. I also use
kemwipes here.
4)Then put it back together and go.
The LCQ has had that tune solution "hard wired" into its code (unlike the
xsq insts). Trusting the guys at Finnigan to write code that tunes my trap
has always worked for me. On the up side those ultramark spikes make great
internal calibrations available to you!! The lcq has the ability to let you
do a 2 point cal correction to the existent tune file as a kind of short
term cal. correction so as to let you put off re-"Ultramarking" the system.
I have sometimes dedicated an ESI probe to Ultramark tunes so as to avoid
having to do the probe rinse step. Not everyone has that luxury.
If anyone has any comments about this that don't jibe with this let me know.
I'd love 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
>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
>-------------------------------------------------------
>
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