A Rapid, Fluorescence-Based Field Screening Technique for Organic Species in Soil and Water Matrices.

Real-time detection of hydrocarbon contaminants in the environment presents analytical challenges because traditional laboratory-based techniques are cumbersome and not readily field portable. In the current work, a method for rapid and semi-quantitative detection of organic contaminants, primarily crude oil, in natural water and soil matrices has been developed. Detection limits in the parts per million and parts per billion were accomplished when using visual and digital detection methods, respectively.

A weight-of-evidence approach to identify nanomaterials in consumer products: a case study of nanoparticles in commercial sunscreens.

Nanoscale ingredients in commercial products represent a point of emerging environmental concern due to recent findings that correlate toxicity with small particle size. A weight-of-evidence (WOE) approach based upon multiple lines of evidence (LOE) is developed here to assess nanomaterials as they exist in consumer product formulations, providing a qualitative assessment regarding the presence of nanomaterials, along with a baseline estimate of nanoparticle concentration if nanomaterials do exist. Electron microscopy, analytical separations, and X-ray detection methods were used to identify and characterize nanomaterials in sunscreen formulations.

Determination of isoelectric points and the role of pH for common quartz crystal microbalance sensors.

Isoelectric points (IEPs) were determined by the method of contact angle titration for five common quartz crystal microbalance (QCM) sensors. The isoelectric points range from mildly basic in the case of Al2O3 sensors (IEP = 8.7) to moderately acidic for Au (5.

Effect of ion energies on the surface interactions of NO formed in nitrogen oxide plasma systems.

The contributions of various gas-phase species in surface reactions are of significant value to assess and improve catalytic substrates for abatement of vehicular emissions. The impact of ions on surface scatter of NO radicals is investigated with an aim toward improving and tailoring surfaces for the reduction or removal of nitrogen oxide (N(x)O(y)) species via inductively coupled plasmas (ICPs). Nascent ions are monitored via mass spectrometry and energy analysis for a variety of N(x)O(y) precursor gases.

Contributions of CF and CF2 Species to fluorocarbon film composition and properties for C(x)F(y) plasma-enhanced chemical vapor deposition.

Inductively-coupled C(x)F(y) (y/x = 2.0-4.0) plasma systems were investigated to determine relationships between precursor chemistry, CF(n) radical-surface reactivities, and surface properties of deposited films.

Comparison of CH, C3, CHF, and CF2 surface reactivities during plasma-enhanced chemical vapor deposition of fluorocarbon films.

The overall character of films deposited using plasma-enhanced chemical vapor deposition relies on the interactions of gas-phase molecules with the depositing film surface. The steady-state surface interactions of CH, C3, CHF, and CF2 have been characterized at the interface of depositing fluorocarbon (FC) films using the imaging of radicals interacting with surfaces (IRIS) technique. IRIS measurements show that the relative gas-phase densities of CH, C3, CHF, and CF2 in mixed FC plasmas depend on the CH2F2/C3F8 ratio.

Gas-phase chemistry in inductively coupled plasmas for NO removal from mixed gas systems.

Inductively coupled rf plasmas were used to investigate the removal of NO from a variety of gas mixtures. Laser-induced fluorescence and optical emission spectroscopy were employed to measure the relative gas-phase density of NO as a function of the applied rf power, gas mixture, and catalytic substrate type. In general, the overall density of NO decreases as a function of applied rf power in both NO and N(2)/O(2) plasmas, but the addition of gases such as H(2)O vapor and CH(4), as well as the presence of Au-coated substrates, significantly affects the behavior of NO in these systems.