“Specifically what I do is weigh molecules,” said Marshall, referring to a workhorse of laboratory techniques called mass spectrometry. He and his research team at Florida State University specialize in analyzing jumbles of molecules, complex mixtures such as blood or crude oil.
Using a magnet to spread out a mixture’s components according to weight — like a prism spreads out light into its rainbow of wavelengths — mass spec applications range from detecting performance drugs in Olympic athletes to determining the age of meteorites.
Marshall took mass spec to new levels of accuracy in 1973 by inventing a way to view the whole spectrum at once rather than one wavelength at a time. Many researchers have since adapted his technique for their own use: one pharmaceutical company has used it to screen 1.4 million drug candidates in the last three months alone, he said.
The analytical chemist himself has worked with companies such as Exxon to examine crude oil. “The more you can tell what components are in a particular stock, the more you know how much to pay for it or what you need to do with it to get the products you want,” he said.
Their record to date is identifying 11,000 different molecules in a sample of oil. “That's close to a fingerprint, a unique identifier for an oil source,” he said. Other “fingerprints” he is working to establish are for crime scenes: the particular accelerant used in an arson case, for example, or identifying characteristics of an explosive such as its packaging and fuse.
Marshall said he has been interested in science as long as he can remember. “I grew up during the Sputnik period. That’s when everyone was excited about science,” he explained. “Then it just increased as time went along.”
Marshall received his undergraduate degree from Northwestern University in 1965 and his Ph.D. from Stanford University in 1970. He is a member of the ACS analytical, biological and physical chemistry divisions.
The ACS Award in Analytical Chemistry is sponsored by Fisher Scientific Co.