Noah,
I believe visualizing the spray is essential to good nanospray LCMS analysis. I
think this so much I have just completed a new product for Flex Ion nanospray
source users, an auxiliary light source, that actually lets you see the spray
before you decide it is OK.
Here is a link to the webpage, hot off my desk last night prior to running an
ad this week for it:
http://www.esisourcesolutions.com/products/auxiliary-light-source-for-thermo-flex-ion-sources/
That is as commercial as I will let myself get on this forum, but your query is
timed perfectly so I ventured near that imaginary line because this is a super
important part of doing good nanocapillary LCMS analysis.
That line about heated capillaries making good spray quality unneeded is
bizarre. I simply cannot help but take strong exception to such a statement. I
mean, sure for regular ESI spray, but not nanospray.
Next we can discuss the limitations of a packed pulled tip column and move you
into a decent steel tip nanospray system, but that is another product!
Let me know what you think, I am always happy to discuss further these
topics....
John Neveu
Rest of post
-----Original Message-----
From: ABRF Discussion Forum <email obscured>] On Behalf Of nod2007
Sent: Saturday, April 28, 2018 1:16 PM
To: <email obscured>
Subject: Re: [ABRF Discussion Forum] Nanoflow chromatographic peak shape
problems
Brian,
I tried to post a lengthy response to this last week but reasons I don't
understand, it got bounced.
I often see what you describe and show. I have always guessed that it has to do
with unstable, sputtering spray. I have never been able to achieve "pretty"
spray on my fusion with the easy nLC1000. I see lots of jagged peaks and the
time scale of the jumps at least seems to be consistent with the observed jumps
I see in the spray. It doesn't seem to effect the number of IDs, but I always
worry about MS1 based quantification from these peaks.
I have a fusion and I'm using ~45 cm, 75 um ID laser-pulled tips, packed with
1.8 um sepax c18, flowing at 350 nl/min. I think the pressure is ~500 bars for
a lot of the run. I think my spray voltage is 1800 V, maybe 2000? capillary
temp 275dC.
In my previous lab, no one even put the cameras on the sources, and it doesn't
seem to be effecting their productivity. The argument is that since the
introduction of the heated capillary, spray quality doesn't matter. I'd feel
better if both my spray and my peaks looked prettier, but I've wasted a lot of
time playing with it even thought it's not clear that it matters at all.
Noah
Noah Dephoure, Ph.D.
Assistant Professor
Sandra and Edward Meyer Cancer Center
Department of Biochemistry
Weill Cornell Medical College
413 East 69th Street, BRB1520
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