A detector that can detect small quantities of explosive material mixed in seawater has been devised by M Sailor and his colleagues at the University of California, San Diego, USA. The device is portable and hence could prove to be immensely useful for detection of sea mines. The device uses polysiloles, a kind of silicon-based plastics which is luminescent. The new device is capable of detecting TNT even at a concentration of 50 parts per billion ( Angewandte Chemie , Vol 40, p2104).