Frank Cheng-Yu Wang

The primary biodegradation of dispersed crude oil in the sea.

Dispersants are important tools for stimulating the biodegradation of large oil spills. They are essentially a bioremediation tool - aiming to stimulate the natural process of aerobic oil biodegradation by dispersing oil into micron-sized droplets that become so dilute in the water column that the natural levels of biologically available nitrogen, phosphorus and oxygen are sufficient for microbial growth. Many studies demonstrate the efficacy of dispersants in getting oil off the water surface. Here we show that biodegradation of dispersed oil is prompt and extensive when oil is present at the ppm levels expected from a successful application of dispersants - more than 80% of the hydrocarbons of lightly weathered Alaska North Slope crude oil were degraded in 60 d at 8 °C in unamended New Jersey (USA) seawater when the oil was present at 2.5 ppm by volume. The apparent halftime of the biodegradation of the hydrocarbons was 13.8 d in the absence of dispersant, and 11 d in the presence of Corexit 9500 - similar to rates extrapolated from the field in the Deepwater Horizon response.

Two valve switching modulator for comprehensive two-dimensional gas chromatography

This paper describes a new design for a valve switching modulation system developed for comprehensive two-dimensional gas chromatography (GC x GC). This system is based on the differential flow and is different from the earlier reported in the literature. It has several advantages and constructed of inexpensive, commercially available parts that are easily installed on most gas chromatographs. Operation is easy and robust and requires no external coolants. This new design allows GC x GC analysis to be conducted in any laboratory environment capable of supporting conventional GC and imposes no additional consumable costs. The system is flexible and permits the use of a wide range of stationary phase combinations. The system has been successfully tested for complete material transfer and is suitable for quantitative analysis. The flexibility of this system is demonstrated using several test mixtures that show its extended application in petroleum, biochemistry, and environmental studies.

Comprehensive three-dimensional gas chromatography mass spectrometry separation of diesel

Diesel, a complex hydrocarbon mixture, was examined using comprehensive two-dimensional gas chromatography (GC×GC) and a field ionization mass spectrometer (FIMS), which preferentially yields molecular ions, providing an extra dimension for component separation. Molecular ions collected at low mass resolution can be assigned an NM-class (Nominal Mass-class) value that does not completely express hydrogen deficiency. In contrast to formulae and Z-class assignments that are possible from ultrahigh mass resolution, NM-class assignments are not unambiguous; however, the separation provided by GC×GC can result in coelution of components that differ in NM-class. Hence, compounds that are unresolved by GC×GC separation can be resolved by FIMS provided they differ in mass. This technique allows for easy, automated data processing, evaluation of coelution on quantitative analysis (e.g., using FID) and the identification of additional chemical species and structures. The development of GC×GC×MS creates new opportunities to improve the ability to determine hydrocarbon composition and structure in complex petroleum and refined petroleum products.