Tandem MS techniques, usually coupled with collision-activated dissociation (CAD), are commonly used to provide insight into the structural aspects of isolated ionized analytes of interest. However, CAD does not always allow definitive determination of the elemental connectivity of ionized molecules. MS/MS based on ion-molecule reactions of isolated analyte ions with carefully selected neutral reagents can be used to obtain more in-depth structural information. Ion-molecule reactions have been used to identify unique structural features in many ionized analytes, such as small organic compounds, lipids, drug metabolites, and biopolymers. However, all previous interfaces for the introduction of reagents for ion-molecule reactions have utilized a single reagent approach. In this study, a multi-ported pulsed valve inlet system was developed that enables fast and efficient successive introduction of three different neutral reagents into a commercial linear quadrupole ion trap instrument for the examination of their ion-molecule reactions with mass-selected ions. The inlet system is easy to attach to the existing hardware without any additional instrument modifications. Furthermore, by integrating automatic triggering, the neutral reagents were successively introduced on a chromatographic time scale. Hence, the pulsed valve interface allows the examination of three different ion-molecule reactions for each ionized component of a complex mixture as they are eluting from a high performance liquid chromatograph. The examination of three different ion-molecule reactions with five repeats was demonstrated for an ionized analyte while it was eluting from an HPLC. The performance of the pulsed valve system was evaluated using several previously described ion-molecule reactions to identify specific functionalities is drug metabolites. The new reagent inlet system not only enables automatic, high-throughput screening of complex mixtures by using at least three different ion-molecule reactions but it also allows rapid testing of new neutral reagents for the identification of functionalities for which diagnostic reactions need to be developed.

Multi-port pulsed valve interface for a linear quadrupole ion trap mass spectrometer to enable rapid screening of multiple functional-group selective ion-molecule reactions during HPLC runs

248th National Meeting (2014)

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