| 摘要 |
A method of detecting a dangerous substance such as explosives or drugs in an article (27) in transit comprises the steps of taking a sample of atmosphere (28) from the vicinity of the article, causing the sample to enter an ionization chamber (24) of a mass spectrometer (30), obtaining a mass spectrum of one or more constituents of the sample, comparing the mass spectrum with one or more reference spectra, and generating a signal indicative of any said dangerous substance in the sample. |
