Infrared Fibers Can Protect Against Chemoterrorism

Hugh Pickens writes "Although most Americans take the safety of their drinking water for granted, ordinary tap water can become contaminated within minutes, says Prof. Abraham Katzir of Tel Aviv University's School of Physics and Astronomy who has developed a fiber-optic system that can detect poisons such as pesticides in water in amounts well below the World Health Organization safety threshold using 'colors' in the infrared spectrum which distinguish between pure and contaminated water. 'With our naked eyes we can't distinguish between pure water and water that contains a small amount of alcohol or acetone. They're all clear,' says Katzir. 'But we can clearly distinguish between liquids using an infrared spectrometer which can distinguish between "colors" in the invisible infrared spectrum.' Connected to a commercial infrared spectrometer, the fibers serve as sensors that can detect and notify authorities immediately if a contaminant has entered a water reservoir, system, building or pipeline. 'Toxic materials are readily available as pesticides or herbicides in the agriculture industry, and can be harmful if consumed even in concentrations as low as few parts per million,' says Katzir. Cities like New York are especially susceptible to a chemoterrorist threat. With many skyscrapers holding water reserves on the top of the building, a terrorist only needs to introduce poison into a tank to wreak havoc. 'A terrorist wouldn't have to kill tens of thousands of people. Only 50 deaths — as horrible as that would be — would cause nationwide panic,' says Katzir."

Comments

Terrorism nuthin - what about H2O pollution?

[zooblethorpe]

Frankly, after hearing and reading about the water infrastructures of many major cities, NYC included, I strongly suspect such a system as this would be more readily useful in verifying that tap water is actually safe from pollutants caused by run-of-the-mill industry and poor water treatment / storage / transportation facilities. Good chunks of the NYC aqueduct system are 100+ years old, with some sections of pipe coming in from the Adirondacks still made of wood, fer cryin' out lout.

Sure, pesticides intentionally dumped in a reservoir are definitely a Very Bad Thing (TM), but polychlorinated biphenyl or polycyclic hydrocarbon aromatics are also *not* Part Of This Nutritious Breakfast (TM). There are plenty of nasties we've put into our *own* water supply, either out of cluelessness or laziness or greed, and new and easy ways of detecting these can only be good.

Cheers,

Re:This capability has been around for 20 years

[deglr6328]

NIR would be inappropriate for this application. If you're looking for contaminant poisons in drinking water you need to have exquisitely sensitive detection thresholds in the part per billion level. A NIR spectrometer using conventional (quartz) fiber optics would be forced to look at the second and third overtones of the fundamental molecular absorption lines in the mid-IR. These overtones have a mere thousandth or hundredth of the relative absorption intensity as the fundamental lines and therefore your signal for extremely low concentrations of contaminants is going to be waaaaay below the noise in your detector. NIRS is best suited for detection of percent level deviations in chemical mixtures, not trace analysis. What this guy from Israel has done is use drawn fibers of silver chloride/bromide, which have spectacular transmittance in the mid-IR, to detect the fundamental absorption bands of trace contaminants using the evanescent waves of IR light that poke slightly outside the surface of a fiber optic. I wish I could find his latest paper that this press release is about though.....