Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
For full article and contact information, see Angew. Chem. Int. Ed. 1999, 38 (12), 1793 - 1795
Poison Gas Test That Fits in your Pocket
A simple biochemical test kit
detects sarin - much more
convenient than before
They are feared as the "poor country's nuclear weapon": the chemical weapons - also known as nerve gases - sarin and soman. They are easy to produce, and the necessary starting materials are cheap and relatively easy to obtain. Sarin and its relatives are deadly and internationally banned. Inspections of potential poison gas production plants are necessary, but are difficult. Until now, the procedure has consisted of taking soil samples on location and analyzing them with complicated special equipment, usually in a distant laboratory. A portable test kit, whose fundamental principles have been introduced by a research group working with Kim D. Janda and Peter Wirsching at California's Scripps Research Institute, could change this.
Many of the rapid tests currently in circulation in portable "suitcase laboratories" are based on the ability of artificially generated antibodies to quickly and accurately recognize specific substances, for which the antibodies have previously been "trained." Biochemists copied this idea, among other things, from the human immune system; here too, antibodies are responsible for crucial friend-foe recognition. In the case of sarin, however, there was a problem: previously, no one could obtain antibodies that reacted with this nerve gas.
Janda and Wirsching came up with a new trick, though. They used the fact that one of the natural decomposition products of sarin, methylphosphonic acid (MPA), has two relatively reactive binding sites. The researchers bound two conspicuous molecular fragments to these sites using an easily obtainable reaction solution. After this reaction, the nearly spherical MPA molecule looks like an air-traffic controller with two signal flags - and like the controller, the "signal flags" make the molecule far more noticeable. Janda and Wirsching were now finally able to "train" special antibodies to recognize MPA molecules modified in this way.
In the future, the search for traces of poison gas could thus look like this: a bit of dust is collected in a suspected weapons manufacturing plant, some solvent containing the "signal-flag reagent" is added, and the mixture is dripped onto a small plate containing the antibodies. If the antibodies recognize the decomposition products of sarin, the reaction mixture changes color, and the terrorist is convicted - without any high-tech machinery.