Air particulate matter (PM) samples were collected from June 2006 to May 2007 for determination chemical elements. PM samples were taken in two size fractions (PM₂.₅ and PM₁₀) with MiniVolume air samplers on rooftops of various buildings (15-25 m above ground) in the city of Riyadh. The samples were subjected...
Ion pairs and solubility related to ion-pairing in water influence many processes in nature and in synthesis including efficient drug delivery, contaminant transport in the environment, and self-assembly of materials in water. Ion pairs are difficult to observe spectroscopically because they generally do not persist unless extreme solution conditions are...
The heterogeneous reactions of ambient particulate matter (PM)-bound polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) with NO₃/N₂O₅, OH radicals, and O₃ were studied in a laboratory photochemical chamber. Ambient PM[subscript 2.5] and PM₁₀ samples were collected from Beijing, China and Riverside, California, and exposed under simulated atmospheric long-range transport conditions...
Atmospheric measurements of semivolatile organic compounds (SOCs) were made at Mt. Bachelor Observatory (MBO), located in Oregon’s Cascade Range, to understand the trans-Pacific and regional transport of SOCs from urban areas. High volume air sampling (~644 m³ for 24 hour periods) of both the gas and particulate phases was conducted...
The synthesis of isoindazoles bearing α-ketoester and α-hydroxyester groups via the coarctate cyclization of ester terminated azo-ene-yne precursors is described. Whereas previous studies on isoindazole formation have shown the reaction to proceed through a kinetic coarctate pathway, functionalization of the terminal acetylene with a methyl ester sufficiently stabilizes the carbene...
Historic and current use pesticides (HUPs and CUPs), with respect to use in the United States and Canada, were identified in trans-Pacific and regional air masses at Mt. Bachelor Observatory (MBO), a remote high elevation mountain in Oregon’s Cascade Range located in the United States, during the sampling period of...
This chapter describes a mass spectrometry-based strategy that facilitates the unambiguous identification and characterization of proteins modified by lipid peroxidation-derived 2-alkenals. The approach employs a biotinylated hydroxyl amine derivative as an aldehyde/keto reactive probe in conjunction with selective enrichment and tandem mass spectrometric analysis. Methodological details are given for model...
This research is the first to quantify complex PAH mixtures in NIST SRMs using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/ToF-MS), with and without extract cleanup, and reports previously unidentified PAH isomers in the NIST SRMs. We tested a novel, high orthogonality GC column combination (LC-50×NSP-35), as...
During the routine determination of the vitamin contents of dehydrated foods, it was observed that nicotine acid values were often lower than expected. The methods of extraction of the food samples were therefore studied, together with the manner of preparation of the assay medium in an effort to secure optimum...