Patent ID: 8723107

Claim:
An apparatus for the analysis of a sample substance, comprising: a. an ion source for producing ions from said sample substance; b. at least two vacuum regions, wherein said vacuum regions are separated from each other by partitions, and wherein said vacuum regions are in communication with each other such that said ions can move through said partitions, wherein the apparatus is operated so that the at least two vacuum regions have different background gas pressures; c. a mass analyzer located in at least one of said vacuum regions, said mass analyzer having a linear entrance axis along which said ions enter said mass analyzer; d. a mass analyzer detector located in a detector region; e. at least one RF multipole ion guide comprising an entrance end and an exit end, wherein ions move through said ion guide from said entrance end to said exit end, wherein said ion guide further comprises a first portion that is a curved, non-segmented portion, wherein said first portion further comprises a first curved ion guide axis extending longitudinally along and radially concentric with the entire length of said first portion, wherein said first portion extends continuously from a first of said vacuum regions, through a first of said vacuum partitions, and into at least a second of said vacuum regions, such that a first part of said first portion is located within said first vacuum region, and a second part of said first portion is located within said second vacuum region, and wherein the background gas pressure in said first vacuum region is sufficiently high that collisions between said ions and background gas molecules occur in said first part, and wherein the background gas pressure in said second vacuum region is sufficiently low that collisions between said ions and background gas molecules essentially do not occur in said second part or in any subsequent part of said ion guide through to said ion guide exit end; f. means for transferring said ions from said ion source into said entrance end of said RF multipole ion guide; g. a first linear axis extending from and tangential to said first curved ion guide axis at said entrance end of said ion guide, wherein said ions enter said ion guide along said first linear axis; and, h. a second linear axis extending from and tangential to said first curved ion guide axis at said exit end of said ion guide, wherein said second linear axis is coincident with said linear mass analyzer entrance axis, whereby the curvature of said second part of said first portion is sufficient such that background particles created in said ion source or in said first vacuum region have essentially no line-of-sight with said detector or detector region.