Patent ID: 6770875
Filing Date: 2004-08-03
Classification: B01D,G01N,H01J

Abstract:
An apparatus for selectively transmitting and determining the mass to charge ratio of ions, comprising:at least one ionization source for producing ions; a high field asymmetric waveform ion mobility spectrometer, comprising: i) an analyzer region defined by a space between first and second spaced apart electrodes, said analyzer region having a gas inlet at a first end and a gas outlet at a second end for providing a flow of gas through said analyzer region, said analyzer region having an ion inlet and an ion outlet, said ion inlet for introducing a flow of ions produced by said ionization source into said analyzer region and said ion outlet for supporting extraction of ions from said analyzer region; ii) an electrical controller connectable to said electrodes and capable of applying an asymmetric waveform voltage and a direct-current compensation voltage to selectively transmit a type of ion in said analyzer region between said electrodes at a given combination of asymmetric waveform voltage and compensation voltage; and iii) a mass spectrometer having a sampler orifice, said sampler orifice being positioned proximate to said ion outlet to receive said selectively transmitted ions for analysis within said mass spectrometer, wherein, said first and second electrodes comprise curved electrode bodies and provide a non-constant electric field therebetween, said ions being selectively focussed in a focussing region created between said curved electrode bodies in said analyzer region.