Integration of a Multichannel Pulsed-Valve Inlet System to a Linear Quadrupole Ion Trap Mass Spectrometer for the Rapid Consecutive Introduction of Nine Reagents for Diagnostic Ion/Molecule Reactions.

Gas-phase ion/molecule reactions have been used extensively for the structural elucidation of organic compounds in tandem mass spectrometry. Reagents for ion/molecule reactions can be introduced into a mass spectrometer via a continuous flow apparatus or through a pulsed inlet system. However, most of these approaches enable the use of only a single reagent at a time. In this work, a multichannel pulsed-valve inlet system was developed for the rapid consecutive introduction of up to nine different reagents or reagent systems into a linear quadrupole ion trap mass spectrometer for diagnostic gas-phase ion/molecule reactions. Automated triggering of the pulsed valves enabled these experiments to be performed on the high-performance liquid chromatography (HPLC) time scale. This enables high-throughput screening of several functionalities in analytes as they elute from an HPLC column.

Adjacent pulsed nanoelectrospray ionization emitters for the alternating generation of ions of opposite polarity.

An approach that allows for adjacent closely spaced nanoelectrospray ionization (nESI) emitters to be pulsed alternately to generate ions of opposite polarity for transmission through a common interface is described. The potential difference between two or more nESI emitters in close proximity is minimized by applying the same polarity to both emitters at any given point in time but with the magnitude of only the active emitter's potential being sufficiently high to sustain a stable spray. The reduced difference in potential between emitters allows the distance between emitters to be decreased to within a few millimeters so that compromises imposed by the use of multiple emitters for the generation of ions from distinct solutions using a common atmosphere interface are minimized.