I have seen a series of peaks that differ by 44 when I was running
nanospray. The samples I ran ( >2mL) were concentrated / desalted on a
C-18 micro concentrator ( <2uL resin) and eluted with 10 uL of 50% ACN,
0.1% formic acid. I found that the water I diluted my samples with had
trace amounts of this delta 44 material that concentrated on the C-18.
Totally swamped my mass spectra at times. I switched to B+J water and the
peaks went away. I never identified the contaminant.
Mike Knierman
knierman@lilly.com
>This might have been discussed before, what are the common polymers,
>detergents or plasticizers that show up in ESI spectra as series of
>polymers differ by 44 amu? If not detergents, can these materials be
>bleeds from tubes, columns, capillary or concentrator membranes?
>
>Hong Li
>
>