Similar instruments have been used to test for traces of gas in seawater.
In Brussels on Friday, officials discussed plans to step up testing for traces of horse meat and phenylbutazone.
"We're moving and testing boxes to test for traces of anthrax as a precautionary measure," said Sandra Carroll, a spokeswoman for the F.B.I. in Newark.
Those samples were tested for traces of the previously undetectable steroid THG, which was the drug at the heart of the Bay Area Laboratory Co-Operative investigation.
The coupons were color-coded, so the clothing could be subjected to forensic testing for traces of gunpowder or explosives, and then correlated with delivery addresses to identify houses that were being used by the I.R.A.
"They can test for traces of explosive or any sort of shrapnel, if it was a high-speed forceful impact, which is what it looks like because the pieces are small and shredded," he said.
Neither of Di Luca's backup blood samples has been tested for traces of CERA, an anemia-fighting substance that is a new generation of the drug EPO, which is banned by the World Anti-Doping Agency.
In 1997, for example, after exterminators in Pascagoula, Miss., sprayed a powerful agricultural insecticide, methyl parathion -- which Dr. Jackson described as a "junior strength nerve agent" -- in hundreds of homes, experts at the federal laboratory huddled for four days and nights until they came up with a reliable urine test for traces of breakdown products of the chemical.
It audits its suppliers to make sure they comply, and has samples of foods tested for traces of DNA that would indicate that some of the ingredients have been genetically modified.The laboratory tests for GM ingredients do not work by screening for genetic modification per se, but look for already known pieces of DNA or protein that reveal the presence of recognised GM foods.
