The quantification and identification of saccharides in pristine marine aerosols can provide useful information for determining the contributions of anthropogenic and natural sources of the aerosol. However, individual saccharide compounds in pristine marine aerosols that exist in trace amounts are difficult to analyze due to their low concentrations. Thus, in this study, we applied gas chromatography–tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring (MRM) mode to analyze the particulate matter with an aerodynamic diameter equal or less than 2.5 μm (PM2.5) samples, and the results were compared with those of conventional GC-MS. To investigate the chemical properties of pristine marine aerosols, 12 PM2.5 samples were collected while aboard Araon, an ice-breaking research vessel (IBRV), as it sailed from Incheon, South Korea to Antarctica. The method detection limits of GC-MS/MS for 10 saccharides were 2–22-fold lower than those of GC-MS. Consequently, the advantages of GC-MS/MS include (1) more distinct peak separations, enabling the accurate identification of the target saccharides and (2) the quantification of all individual saccharide compounds with concentrations outside the quantifiable range of GC-MS. Accordingly, the time resolution for sampling saccharides in pristine marine aerosols can be improved with GC-MS/MS.
A cheaper, greener approach for the synthesis of highly monodisperse and tunable size CdSe semiconductor quantum dots was developed by thermolysis of a mixed solution of CdO and Se in non-coordinating solvent 1-octadecene at 240 °C. Systematic vary of the precursor molar ratios allowed the particle size (from 2.5 nm to 5.5 nm) to be tuned and the size distribution (full width at half maximum of photoluminescence spectra from 26 nm to 37 nm) to be controlled. The results revealed that initial Cd:Se molar ratios play an important role in controlling both the size and size distribution of the as-prepared CdSe quantum dots. Moreover, the obtained CdSe quantum dots are all of zinc blende phase. The possible reason was discussed. The reaction has been conducted in relatively low temperature at 210 °C in the absence of expensive organic phosphine ligands, such as trioctylphoshine and trioctylphoshine oxide. This approach has great value for both the laboratory research and industrial application in term of "green chemical principles".
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