It is strange how coincidental this discussion has been to my past week. We have had three projects messed up by siliconized tubes during this time.
Two were due to researchers grabbing the wrong bag of tubes, and the third was a sample from a collaborator. In each case, siliconizing reagent from the tube swamped out peptide signals during ESI-LC-MS and also MALDI analyses.
The predominant signals observed (but plenty of others were scattered through the gradient) were a singly charged m/z 419 and a dimer ion at 836. Is this what most of you have seen?
In any event, we have found that PCR tubes provided by Robbins Scientific (Part #1045-00-0) are generally relatively cleaner. Methanol washing is a good idea as well.
-Elliott
>>> Ruth Hogue Angeletti <angelett@aecom.yu.edu> 02/04 8:16 AM >>>
Dear Ken
Beyond the problems you describe, we've had other tube problems lately that
have been driving us nuts. We had happily been using tubes from two
manufacturers for several years. When reordered recently, the same part
number came DNase-RNase free, with coatings that we can't live with. We
are now using one kind of Eppendorf, but their cleanest plastic doesn't
seem to come in a 0.5 ml size. With all the expensive instruments, we have
to torment over a one penny item. All knowledge would be appreciated.
Thanks
Ruth
At 12:20 PM 2/4/99 +1100, Ken Mitchelhill wrote:
>Colleagues,
>
>we have had discussions in the past regarding leeching of "detergent like"
>polymers from tubes that swamp ESI spectra.
>
>I thought I was using relatively MS clean tubes until recently when I have
>been undertaking an exhaustive study of a protein digest by nano-ESI MS/MS
>where I have had, because of the size of the project, to store fractions
>for a few weeks at -20 degrees C.
>
>I have noticed that fractions containing more than about 25% acetonitrile
>contain these pesky polymers after about a weeks storage. The polymers are
>not present in the original solvent and their time dependent appearance
>seems also to be organic concentration dependent.
>
>Apart from the obvious solutions like doing the experiment quicker or
>removing the organic solvent by evaporation prior to storage, does anyone
>out there have other suggestions.
>
>In particular, is anyone using a tube (specific make and model required
>here) where one can store say 60% acetonitrile for weeks without extracting
>polymeric material from the plastic?
>
>Regards....Ken
>
>********************************
>
>Ken I. Mitchelhill
>The John Holt Protein Structure Laboratory
>St. Vincent's Institute of Medical Research
>41 Victoria Parade
>Fitzroy 3065 Victoria
>AUSTRALIA
>
>Telephone: 61-3-9288 2480
>Facsimile: 61-3-9416 2676
>
>Email: k.mitchelhill@medicine.unimelb.edu.au
>
>Laboratory: http://www.medstv.unimelb.edu.au/WWWDOCS/SVIMRdocs/JHPSL.html
>ABRF: http://www.abrf.org
>
>***********************************
>
>
>
>
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