WASHINGTON — Three simple numbers will prove whether sarin was used to gas Syrians last month: 99-125-81.
Chemists this week around Europe are feeding samples of bodily tissue and dirt collected after chemical attacks in Syria into sophisticated machines, waiting for those three numbers to read out in a bar graph on a computer screen. The numbers are sarin’s fingerprint, said Carlos Fraga, a chemist who specializes in nerve agent forensics at the Pacific Northwest National Laboratory in Richland. “You’re always going to see that.”
In a process that takes about two weeks, chemists have to turn that solid dirt and tissue first into liquid and then into gas.
Chemists dissolve the samples by putting them into a solvent, such as methanol, and shaking them, Fraga said. Then that’s injected into a gas chromatograph, which looks like a big oven. It heats the liquid, turning it into a gas, then acts as a giant sorting machine. The suspected sarin is separated, but at this point scientists still can’t figure out what it is. It’s just not mixed up with everything else anymore.