Security staff at airports and embassies could use a spray-on version of the test as a quick and handy way of finding traces of explosives such as TNT and Semtex. He says that a big advantage of this approach is that it picks out all major compounds containing nitrate, a chemical group found in many common explosives.
Laboratories normally use chromatography to detect traces of explosives.
A solution of the suspect sample is forced through a stainless steel tube filled with a silica-based particles. Because different substances flow through the tube at different speeds, the explosive becomes separated from the other components of the sample. The concentration of the explosive can then be determined by bathing this part of the sample in ultraviolet light and measuring how much light is absorbed. Organic compounds in soil, for example, can also absorb ultraviolet light, which can mask traces of explosive. So McGuffin and her colleague John Goodpaster turned to a technique called fluorescence quenching.