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Figure 10 - click on each panel to enlarge
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The panels at the right
illustrate SCIMS results from R/V Oceanus Cruise 367 south
of Martha’s Vineyard in June, 2001. The upper panel
shows microlayer (red) and subsurface (blue) CDOM fluorescence
during a 5-hr transect at 41º14.18’N, 70º
38.16’W. Surface enrichments were evident throughout
the transect. The middle panel presents the total ion and
mass chromatograms (TIC and m/z 777) for the first 15 of 30
samples collected. These were flow-injected in triplicate
into a Finnigan LCQ ITMS and ionized using electrospray. Variation
in the TIC is minimal since total organic carbon is only slightly
enriched in the microlayer. The mass chromatogram for m/z
777 shows more variation, suggesting preferential enrichment.
The lower panel is the electrospray spectrum of sample extract
#14, which shows a broad envelope of ions from m/z 100-1100
representing primarily protonated or sodiated parent ions.
Prominent ions from a series of unknown but related compounds
are observed at 777, 819, 939, and 981. Low mass defects along
with mass differences of 162 amu suggest the presence of glycosyl
(sugar) moieties in these structures. Ions at 777 and 939
for example, may derive from mono- and diglycosyldiglycerides.
This will be explored further using a combination of ionization
modes and multistage (MSn) techniques.
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