Patent ID: 7034292

Claim:
An apparatus for analyzing chemical species, comprising: an ion source for operation at substantially atmospheric pressure to produce ions from a sample substance; at least one vacuum stage having means for pumping away gas to produce a partial vacuum; means for delivering said ions from said ion source into one of said at least one vacuum stage; a collision cell configured in at least one of said at least one vacuum stage such that said ions may be directed into said collision cell, wherein said collision cell comprises at least one higher neutral gas pressure region, in which the neutral gas is controllably elevated to be higher than in other vacuum regions proximal to said collision cell, such that collisions between said ions and neutral gas molecules occur within said higher neutral gas pressure region while such collisions essentially do not occur within other vacuum regions proximal to said collision cell; a detector configured in one of said at least one vacuum stage; at least two multipole ion guide segments, each of said multipole ion guide segments having a plurality of poles, wherein at least a portion of each of said at least two multipole ion guide segments is positioned within said collision cell; and independent RF frequency and DC voltage sources applied to each of said at least two multipole ion guide segments, wherein said RF frequency and DC voltages applied to each of said at least two multipole ion guide segments are controlled independently of each other.