Dr. Rayson’s research interests pertain to the investigation of metal atoms and ions in complex chemical environments. These studies involve the elucidation of atomization, ionization, and excitation mechanisms occurring within the high temperature systems of inductively coupled argon plasma discharges and resistively heated graphite furnace atomizers. Alternately, studies of the chemical moieties on the cell walls of plants which are responsible for the selective binding of heavy metal ions from contaminated waters and soils are also pursued in the Rayson laboratory. The elucidation of these complex chemical processes necessitates the implementation of numerous, independent techniques. These “tools” have included the use of temporally and spectrally resolved atomic emission and absorption spectroscopies, laser excited luminescence measurements in both time and wavelength domains, multi-nuclear NMR spectroscopy, and frontal affinity chromatography. An example of the application of such an arsenal of techniques has been the elucidation of multiple (i.e., three) metal-coordination sites involving carboxylate groups and two additional ion-exchange site containing carboxylate and sulfonate groups, respectively, on the surface of a cell wall material derived from the plant Datura innoxia.
It is only with an understanding of the chemical and physical processes occurring within these complex systems that the required level of predictability can be realized for their full utilization. This includes the elimination of matrix interferences in inductively coupled plasmas and heated graphite atomizers and the application of biologically generated materials for the inexpensive remediation of contaminated soils and waters.
1. H.-Y. D. Ke, G.D. Rayson and P.J. Jackson, "Luminescence Study of Eu3+ Binding to Immobilized Datura innoxia Biomaterial," Environ. Sci. Technol., 27 (1993) 2466-71.
2. J. R. Lujan, D. W. Darnall, P. C. Stark, G. D. Rayson J. L. Gardea-Torresdey, “Metal Ion Binding By Algae and Higher Plant Tissues: A Phenomenological Study of Solution pH Dependence,Solvent Extraction and Ion Exchange 12 (1994) 803-816.
3. G. D. Rayson, D. W. Darnall and P. J. Jackson, “Recovery of Toxic Heavy Metals from Contaminated Ground Water, “ Radioactive Waste Management and Environmental Restoration, 18 (1994) 99-108.
4. H.-Y. D. Ke, W. L. Anderson, R. M. Moncrief, G. D. Rayson and P. J. Jackson, “Luminescence Studies of Metal Ion-binding Sites on Datura innoxia Biomaterials,” Environmental Science and Technology 28 (1994) 586-589.
5. R. M. Moncrief, W. L. Anderson, H.-Y. D. Ke, G. D. Rayson and P. J. Jackson, “Impact of pH on Binding Metal ions by Datura innoxia Biomass,” Separation Science and Technology 30 (1995) 2421-2428.
6. L. R. Drake, T. R. Baker, P. C. Stark, and G. D. Rayson, “A Laser Based Spectrofluorometer for the Efficient Probing of Metal Ion Binding Sites on Solid Biomaterials,” Instrumentation Science and Technology 23 (1995) 57-69.
7. L. R. Drake, Shan Lin, and G. D. Rayson, “Chemical Modification and Metal Binding Studies of Datura innoxia,” Environmental Science and Technology 30 (1996) 110-114.
8. L. R. Drake and G. D. Rayson, “Plant Materials for Metal Selective Binding and Preconcentration,” Anal. Chem. 68 (1996) 22A (Invited).
9. G.D. Rayson and D.Y. Shen, "Inductively Coupled Argon Plasma Axial Viewing Absorption Measurements Using a Power Modulated Plasma," Spectrochim. Acta, Part B, 47B (1992) 553.
10. G. D. Rayson and M. R. Fresquez, “The Thermal and Temporal Impact of Mg and Pd Chemical Modifiers on Thermal Pretreatment Cu and Ag Analyte Loss in ETA-AAS,” Canadian Journal of Applied Spectroscopy 38 (1993) 114-119.