Development of an ion transmission enhanced tandem ion guide system for triple quadrupole mass spectrometer

The mass spectrometer coupled to atmospheric pressure ionization source needs to have differential pumping system in order to maintain high vacuum in analyzer part. Commercial triple quadrupole mass spectrometer typically has from 3 to 4 differential pumping stages and the RF ion guide was generally utilized as an ion focusing device in higher pressure region of ion path. The ions generated under atmospheric pressure needs to be efficiently focused to minimize the loss of ion prior to introducing into quadrupole analyzer by using RF lens system. Using a QqQ which has 4 differential pumping stages, we have investigated fringing field of RF ion guide installed in second and third differential pumping stage and finally the sensitivity was improved 5 times.