Derek,
I have not specifically tried the following methods with DMF so I'm not
certain they will work. All are based on either binding the analyte to the
target surface or the differential solubility of sample/matrix and
contaminants in water.
Mock, Sutton and Cottrell (1992) RCMS, 233-238 took advantage of the
properties of a gold surface to bind analytes and mentioned that surfaces
could also be improved by pre-spraying with nitrocellulose dissolved in an
organic solvent such as acetone (btw, if you contemplate electrospraying
acetone/nitrocellulose, make certain your life insurance is paid up!).
Xiang and Beavis (1994) RCMS 8, 199-204 used physical crushing to form
microcrystals of alphacyanohydroxycinnamic acid/sample which allowed
removal of bulk solvent and washing without apparent loss of sample.
Vorm, Jensen, Mortensen and Mann (EMBL) (sorry I don't have a complete
reference) used a matrix/nitrocellulose mixture in acetone/isopropanol to
bind the analyte followed by water extraction. The technique does require
drying the sample, but you can try it without a sample drydown.
I hope this proves to be of some use.
regards,
At 4:58 PM +0100 5/29/01, Derek Bradley wrote:
>Hi All,
>
>I have a colleague who is asking me to analyse via MALDI, a substance which
>is dissolved in DMF and which he swears blind is insoluble in anything
>normal for MALDI like acetonitrile or methanol. With the boiling point of
>DMF being about 154C I figure it's going to be forever and a day before
>even 1ul evaporates normally from the spot so I was hoping someone out
>there has had experience of DMF based samples and can offer some useful tips.
>
>I've asked him to try blending the sample with amounts of acetonitrile to
>see if this will speed things up without dropping his substance out of
>solution. I'm not convinced sticking the plate in an oven for a few hours
>is the way to go although using a hairdryer has been mooted....
>
>Any helpful hints will be gratefully received!!
>
>Thanks,
>
>Derek Bradley
>Dept. of Medicine
>UCL
>London
Gary Hathaway
Director, PPMAL
1-626-395-2769
hathaway@its.caltech.edu
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