Identification and Linkage of Tarballs from the Coasts of Vancouver Island and Northern California Using GC/MS and Isotopic Techniques

During January and February 1996, a significant number of tarball/patty incidents occurred along the coasts of Vancouver Island, Washington, Oregon, and California. Samples of the tarballs were collected from the affected beaches and analyzed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/flame ionization detector (GC/FID) using a tiered analytical approach developed for determining the origin of oils. Selected samples were further analyzed using a carbon isotopic technique. Also, the relative abundances of a large number of “source-specific marker” compounds, in particular alkylated series of polycyclic aromatic hydrocarbons within the same alkylation isomeric groups, were compared. Results of the analysis revealed that (1) California/Oregon samples were chemically similar and consistent with the same source. They were identified to be bunker type fuel; (2) The tarball samples collected from British Columbia and Ocean Shores, Washington were chemically similar and consistent with the same source (also bunker type fuel). They were found to be similar to but may have a source different than the California/Oregon samples; (3) The source of the tarball/patty samples was neither Alaska North Slope oil nor California Monterrey Miocene oil; (4) The spilled oil samples have been highly weathered since release, and the California samples were more heavily weathered than the British Columbia samples.     

The detection of various opiates and benzodiazepines by comprehensive two‐dimensional gas chromatography/time‐of‐flight mass spectrometry

A technique using comprehensive two‐dimensional gas chromatography/time‐of‐flight mass spectrometry (GC × GC/TOFMS) is applied to qualitative and quantitative drug testing. Human serum was ‘spiked’ with known quantities of benzodiazepines and a ‘street heroin’ mixture including some of the major metabolites and impurities. The sample components were extracted from the matrix by solid‐phase extraction (SPE). Constituents containing polar hydroxyl and/or secondary amine groups were derivatised with N‐methyl‐N‐(tert‐butyldimethyl)trifluoroacetamide (MTBSTFA) to improve the chromatographic performance. An orthogonal separation of the matrix constituents was achieved by coupling a DB‐5ms (5% phenyl) to a BPX50 (50% phenyl) GC column. The eluant was focused onto the second column by a twin‐stage cryo‐modulator. Rapid 6 s modulation times were achieved by transfer from a 30 m × 0.25 mm (length × internal diameter) to a 2 m × 0.1 mm column. TOFMS with rapid spectral acquisition (≤500 spectra/s) was employed in the mass range m/z 40–650. A clean mass spectrum was obtained for each analyte using mass spectral deconvolution software. The sensitivity and repeatability of the method were evaluated by the preparation of calibration standards for two benzodiazepines, flunitrazepam and its major metabolite 7‐aminoflunitrazepam (7‐amino‐FN), in the concentration range 5–1000 ng/mL. The limits of detection (LODs) and limits of quantitation (LOQs), calculated by repeat injections (×10) of the lowest standard, were 1.6 and 5.4 ng/mL (flunitrazepam); 2.5 and 8.5 ng/mL (7‐amino‐FN), respectively. There is scope to extend this protocol to screen a large number of drugs and metabolites stored in a library database. Copyright © 2009 John Wiley & Sons, Ltd.     

Homogeneous periodic heat flow via nonequilibrium molecular dynamics

Two nonequilibrium methods for simulating homogeneous periodic heat flow are applied to 108 three-dimensional soft spheres in both the fluid and face-centered cubic solid phases. Both nonequilibrium methods use irreversible thermodynamics to express heat conductivity in terms of the work required to generate heat flow. The Evans-Gillan method, derived from Green-Kubo theory, correctly reproduces Ashurst's heat conductivities. An approach based on Gauss' principle of least constraint, in which the heat flow is constrained to a fixed value, fails this test. Heat flow is an inhomogeneous, nonlinear function of particle velocities and coordinates. Thus, Gauss' principle cannot be relied upon for treating inhomogeneous nonlinear nonholonomic constraints.Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract #W-7405-Eng-48. Work performed at U.C. Davis-Livermore with the support of the Army Research Office and the Air Force Office of Scientific Research.     

On the Investigation of Stochastic Global Optimization Algorithms

This discussion paper for the SGO 2001 Workshop considers the process of investigating stochastic global optimization algorithms. It outlines a general plan for the systematic study of their behavior. It raises questions about performance criteria, characteristics of test cases and classification of algorithms.     

Oxygen-17 and carbon-13 nuclear magnetic resonance spectra of thiophene- and pyrrole-2-carboxaldehyde condensation products prepared from ephedrine derivatives

Natural abundance ¹⁷O nmr (acquired in acetonitrile at 70°) and ¹³C nmr (acquired in deuteriochloroform at 37°) spectroscopic data for four oxazolidines and related imino alcohols are reported: relationships of chemical shifts and ¹⁷O line widths at half-heights to structures are discussed.     

Redefined element factor for simplified i.d.t. design

It is shown that the response of interdigital transducers with uniform periodicity and duty factor can be written as the product of a redefined element factor and an array factor even if the magnitude and phase of the electrode voltages are completely arbitrary.