Researchers at the National Institute of Standards and Testing in Maryland, USA, have developed an instrument that can detect gases present in infinitesimal amounts (Environmental Science & Technology, Vol 28, No 6). The instrument uses microwaves similar to those used in microwave cookers to measure as little as 10 parts per billion of any volatile organic or inorganic matter.

The sample gas is pulsed through a nozzle into a detection cavity where it is chilled down to --272oC. At this temperature, molecules can be distinguished from one another through their light absorption patterns. The device can be used to monitor automotive emissions and indoor air quality.