Patent ID: 8030610

Claim:
A mass spectrometer comprising: a) an ion source that generates ions of an analyte of interest and one or more background ions; b) a mass separator that receives ions generated by the ion source, the mass separator substantially separating ions in a first range of mass-to-charge ratio values and transmitting at least a portion of the ions in the first range of mass-to-charge ratio values through an exit; c) a reaction region containing a neutral organic chemical species, the reaction region receiving the ions transmitted through the exit of the mass separator and causing collisions of at least a portion of the transmitted ions with the neutral organic chemical species that reacts with the one or more background ions to change the m/z value of one or more background ions, but that does not substantially react with the ions of the analyte of interest, thereby allowing only ions with mass-to-charge ratio values in a second mass-to-charge ratio range to be extracted from an exit of the reaction region; and d) an ion detector that detects ions extracted from the reaction region, the ion detector detecting the ions of the analyte of interest with a level of noise that is reduced by the collisions in the reactive region, wherein a mass-to-charge ratio of the ions of the analyte of interest can be determined from the ion detection.