Calling all LCQ users....
I am running nanospray on my LCQ using a solvent of 70% methanol:1% formic
acid. Almost all samples from in-gel digests and are cleaned up by reverse
phase micro guard column (LC Packings) and eluted in the above solvent.
Over time a transparent gel-like material builds up in a disc-shaped area
centred around the capillary orifice on the LCQ inlet and also in the bore
of the capillary itself, necessitating removal and cleaning. After every
few samples and always at the end of the day, the orifice is flushed with a
50% methanol:water mix, but the gel does not dissolve in this. It appears
to have limited solubility in neat methanol.
Has anyone else seen this? Can electrospray conditions and heat lead to
polymerisation between methanol and formic acid? Is the gel anything
related to acrylamide? Can it be prevented?
Help!!
Len
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Dr Len C. Packman
Assistant Director of Research
Protein and Nucleic Acid Chemistry Facility
Department of Biochemistry
University of Cambridge
80 Tennis Court Road
Old Addenbrookes Site
Cambridge, CB2 1GA, UK
Tel: +44 (1223) 333639
FAX: +44 (1223) 766002
e-mail: lcp2@mole.bio.cam.ac.uk
Visit my WWW page at http://www.bio.cam.ac.uk/proj/adr/PNAC/pnac.html