Corona discharge ion source for analytical instruments

Abstract

An ion mobility spectrometer comprises an ion mobility cell (10) into which molecules of a sample to be analysed are introduced. The ion mobility cell (10) is doped with ions produced by a corona discharge ionisation source (40). In one mode of operation, the corona discharge ionisation source (40) operates to produce a continual dopant stream, and in a second mode of operation, the corona discharge ionisation source (40) produces dopant ions selectively. In the non-continuous mode of operation, the ion mobility cell (10) may be doped with chemical dopant ions instead, switching between the two dopant regimes being accomplished very rapidly. The ion mobility spectrometer is particularly suitable for the detection of explosive compounds and narcotics, the ion mobility spectrum of explosives doped with ions from the corona discharge ionisation source differing from the ion mobility spectrum of such explosive compounds doped with chemical dopants.

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