Postdoctoral research associate Cornell University, Ithaca, New York, 1965-1967. Research scientist Hercules, Inc., Wilmington, Delaware, 1967-1971. Associate foundation scientist Southwest Foundation Research and Education, San Antonio, 1971-1976.
Senior research scientist Southwest Research Institute, 1976-1986. Associate division chief Drug Testing Laboratory, United States Air Force, 1986-1988. Function chief Occupational and Environmental Health Laboratory at Brooks Air Force Base, 1988-1992.
Consultant chemist Air Force Center for Environmental Excellence, Brooks Air Force Base, Texas, 1992-1994. Alternate division chief Armstrong Laboratory, 1994-1999, chief chemistry division, since 1999.