Isolation and Monitoring of the Endohedral Metallofullerenes Y@C82 and Sc3@C82:On-Line Chromatographic Separation with EPR Detection

The direct coupling of high-performance liquid chromatography (HPLC) with on-line electron paramagnetic resonance (EPR) detection is demonstrated for monitoring separations of endohedral metallofullerenes (M@C2n). The HPLC-EPR approach readily permits detection of the paramagnetic species, such as Y@C82 and Sc3@C82, in the presence of the dominant empty-cage fullerenes (C60, C70) and diamagnetic metallofullerenes (e.g., M2@C2n). The results indicate that on-line EPR provides a noninvasive, selective detector for HPLC metallofullerene separations that is readily adaptable to air-sensitive and/or labile compounds. Specifically, the “EPR-active” metallofullerenes, Y@C82 and Sc3@C82, are selectively monitored on-line for an initial separation of the metallofullerene fraction from the dominant empty-cage fullerenes utilizing a combination of polystyrene columns. This preparative “cleanup” procedure is followed by HPLC-EPR separation and monitoring of Y@C82 and Sc3@C82 species using a selective tripodal π-acidic-phase column (Trident-Tri-DNP) for the final stages of isolation

Short-term temporal variation in PM2.5 mass and chemical composition during the Atlanta Supersite Expriment, 1999

Measurements in urban Atlanta of transient aerosol events in which PM2.5 mass concentrations rapidly rise and fall over a period of 3-6 hr are reported. The data are based on new measurement techniques demonstrated at the U.S. Environmental Protection Agency (EPA) Atlanta Supersite Experiment in August 1999. These independent instruments for aerosol chemical speciation of NO3-, SO4(2-), NH4+, and organic and elemental carbon (OC and EC), reconstructed the observed hourly dry PM2.5 mass to within 20% or better. Data from the experiment indicated that transient PM2.5 events were ubiquitous in Atlanta and were typically characterized by a sudden increase of EC (soot) and OC in the early morning or SO4(2-) in the late afternoon. The frequent temporal decoupling of these events provides insights into their origins, suggesting mobile sources in metro Atlanta as the main contributor to early morning PM2.5 and more regionally located point SO2 sources for afternoon PM2.5 events. The transient events may also have health implications. New data suggest that short-term PM2.5 exposures may lead to adverse health effects. Standard integrated filter-based techniques used in PM2.5 compliance monitoring networks and in most past PM2.5 epidemiologic studies collect samples over 24-hr periods and thus are unable to capture these transient events. Moreover, health-effects studies that focus on daily PM2.5 mass alone cannot evaluate the health implications of the unique and variable chemical properties of these episodes

Investigation into a surface plasmon related heating effect in surface enhanced Raman spectroscopy

10.1021/ac070497wAnalytical Chemistry79238870-8882ANCH

Effects of N-methyl pyrrolidone on the uptake of hypericin in human bladder carcinoma and co-staining with DAPI investigated by confocal microscopy

Technology in Cancer Research and Treatment65383-394TCRT

Automated HPLC Separation of Endohedral Metallofullerene Sc@C2n and Y@C2n Fractions

We describe an automated HPLC separation of the endohedral metallofullerenes such as Sc@C2n and Y@C2n from empty-cage fullerenes utilizing two polystyrene chromatographic columns (500 and 1000 Å) in series. Rapid separation of the metallofullerene fraction from the empty-cage fullerenes (e.g., C60) under anaerobic conditions is achieved. For the isolated Sc@C2n fraction, all even-carbon-membered species from Sc2@C74 to Sc2@C104 were identified by negative-ion chemical ionization mass spectrometry. In addition, Sc3@C82 was a prominent component of this fraction. For the separated Y@C2n sample, the mass spectral data indicate the presence of Y@C82 and all even-carbon-numbered diyttrium species from Y2@C82 to Y2@C104.