Improved ion transmission from atmospheric pressure to high vacuum using amulticapillary inlet and electrodynamic ion funnel interface

A heated multicapillary inlet and ion funnel interface was developed to cou ple an electrospray ionization (ESI) source to a high-vacuum stage for obta ining improved sensitivity in mass spectrometric applications. The inlet wa s constructed from an array of seven thin-wall stainless steel tubes solder ed into a central hole of a cylindrical heating block. An electrodynamic io n funnel was used in the interface region to more effectively capture, focu s, and transmit ions from the multicapillary inlet. The interface of seven capillary inlets with the ion funnel showed more than 7 times higher transm ission efficiency compared to that of a single capillary inlet with the ion funnel and a 23-fold greater transmission efficiency than could be obtaine d using the standard orifice-skimmer interface of a triple-quadrupole MS. T he multiple-capillary inlet and ion funnel interface showed an overall 10% ion transmission efficiency and approximately 3-4% overall detection effici ency of ions from solution based (i.e., prior to electrospray). The improve d performance was achieved under conditions where ESI operation is robust a nd results in a significant increase in dynamic range.