Selective ionization using high frequency filtering of reactive ions

摘要

Selective ionization at atmospheric or near atmospheric pressure of a sample diluted in air is provided in multiple steps. Initially, components of air and/or other gas are ionized to generate reactive ions. The reactive ions are then filtered using a high frequency filter to yield selected reactive ions. Thereafter, the selected reactive ions are reacted with sample molecules of a sample being analyzed in a charge transfer process. Depending on the properties of the sample molecules, the filter may select some reactive ions to enter the sample zone and block others entirely thus controlling ion chemistry and charge transfer yields in the sample zone. The described system is directed to controlling ions at the ion source level, using a high frequency filter technique, in connection with subsequent analysis. The method generates the ions of choice for subsequent analysis in such platforms as ion mobility and differential mobility spectrometers.

主权项

1. A selective ionization device, comprising:
an ionization zone in which reactive ions are generated, the reactive ions being generated from a gas that is separate from a sample being analyzed; a sample zone that contains the sample being analyzed; and a high frequency filter that receives the reactive ions propelled from the ionization zone and delivers selected reactive ions to the sample zone wherein the reactive ions from the ionization zone are selectively filtered via control of electrodes of the high frequency filter to generate the selected reactive ions, wherein the electrodes are controlled via an asymmetric waveform alternating between high and low fields that subjects the reactive ions to oscillations within the high frequency filter resulting in separation of the reactive ions based on differences between high field and low field mobilities of the reactive ions, wherein a compensation voltage is further applied to then deliver the selected reactive ions from the high frequency filter, wherein, in the sample zone, the selected reactive ions react with the sample molecules of the sample being analyzed in a charge transfer process at atmospheric or near atmospheric pressure.