Research in the Aquatic Chemistry Laboratory

1. Sources, fate and impacts of pharmaceutical chemicals, steroids and xenoestrogens (PCXSs) in aquatic ecosystems.  GC-MS and LC-MS/MS are used to measure PCSXs in water, sediments and fish in the tidal freshwater Potomac River through an ongoing study in Hunting Creek (Alexandria, VA) supported by Alex Renew Enterprises. Our research collaborators contribute vital expertise in analytical chemistry (Dr. Tom Huff of the Mason Shared Research Instrumentation Facility -- extraction technology, GC-MS and LC-MS/MS), and fish and plankton ecology (Drs. Chris Jones and Kim De Mutsert from the Environmental Science & Policy Department).  Michael and Monica
Monica Ahir (MS Chemistry & Biochemistry) and Michael Cagle (MS Environmental Science & Policy) are investigating the sources, distribution and food chain transfer of PCSXs in the tidal freshwater Potomac River. Both use LC-MS/MS (Waters Alliance 2690 HPLC with Micromass Quattro micro triple-stage-quadrapole mass spectrometer) in their projects.

Selected Publications
  • Thomas, P.M. and G. Foster.  (2004) Determination of nonsteroidal anti-inflammatory drugs, caffeine and triclosan in wastewater by gas  chromatography/mass spectrometry.  J. Environ. Sci. Health, Part A, 39, 1969-1978
  • Thomas, P.M. and G. Foster.  (2005)  Tracking acidic pharmaceuticals, caffeine and triclosan through the wastewater treatment process.  Environ. Toxicol. Chem. 24, 25-30
  • Shala, L. and G. Foster (2010) Surface Water Concentrations and Loading Budgets of Pharmaceuticals and Other Domestic-Use Chemicals in an Urban Watershed (Washington, DC, USA).  Arch. Environ. Contam. Toxicol. 58, 551-561
  • Arya, G., S. Tadayon, J. Sadighian, J. Jones, K. De Mutsert, T. Huff and G. Foster (In Press)  Pharmaceutical chemicals, steroids, xenoestrogens in water, sediments and fish from the tidal freshwater Potomac River (Virginia, USA). J. Environ. Sci. Health, Part A (online open access)
2.  Binding of pharma-chemicals to aquatic humic substances (AHS). Fluorescence spectrophotometry is used to experimentally determine sorption constants (Kd) through fluorescence quenching. Carol Ajjan (PhD Chemistry & Biochemistry) and Dan Cairnie (BS Chemistry) use a Shimadzu RF 6000 fluorometer to determine the binding of a variety of pharma-chemicals in several sources of AHS. Stern-Volmer and Ryan-Weber models are used with non-linear curve fitting to derive Kd values from quenching experiments.
3.  Acid dissociation and charge properties of aquatic humic substances (AHS). Auto-titration is used to determine the acid dissociation constants of AHS obtained from local sources (DAX-8 resin isolation). Sharon Becker (BS/MS Chemistry-Biochemistry) and June Kang (MS Chemistry) use Mettler-Toledo GS10 auto-titrators in conjuction with a modified Henderson-Hasselbalch model (MHHM) and non-linear curve fitting to obtain acid dissociation constants (KaSharonJune) in AHS.