Advancements in the interface of chromatography and mass spectrometry

The challenge of creating an interface between chromatographic methods and mass spectrometers has been sufficiently resolved to provide analytically useful instruments. Currently, there are two problems associated with many of the existing interface designs. Many interfaces are of a very specific design and thus have a limited analytical usefulness. Other interface designs inefficiently transfer ions into the mass spectrometer. Each of these shortcomings were addressed independently.; A method for the soft ionization of gas chromatographic (GC) analytes was developed using gas phase proton transfer reactions with electrospray ionization (ESI) generated ions. The technique increases the analytical usefulness of current ESI/MS instruments and allows for the selective MS analysis of chromatographicaly resolved analytes. Our studies reveal that the ionization occurs by proton transfer from protonated solvent clusters produced by ESI. The design and benefits of a fixed volume reaction cell for the proton transfer reactions are shown. We determine that this is an efficient and analytically useful method of ionization for GC effluent. Our prototype interface achieves a reproducible detection limit of 100 femtomoles on column for high proton affinity analytes. This technique is capable of selective ionization for analytes with a proton affinity comparable to or greater than that of the solvent used in the ESI spray.; Matrix Assisted Laser Desorption (MALDI) and Electrospray Ionization (ESI) are currently the most widely used ionization techniques for the mass spectral analysis of large, non-volatile analytes. It is becoming increasingly popular to interface these ionization sources with the quadrupolar ion trap. The ion trap as a mass spectrometer offers low detection limits, adequate resolution, robustness and MS/MS capabilities. Currently, ions created externally by ESI or MALDI are injected into ion trap instruments while the rf potential is on. The injection efficiency of this methodology is very low and as a result, the instrument functions well below its theoretical capability. In this dissertation, we investigate the effectiveness of a methodology, referred to as “sudden-onset rf”. In this approach, the rf potential on the ring electrode is left off until an injected ion bunch has traversed into the ion trap. Ion trajectory simulations performed by SIMION demonstrate the effectiveness of trapping ions with the sudden-onset rf method in the ion trap “stretched” electrode geometry. All the ions contained within a particular ion retention volume at the time of rf onset are retained. The size and shape of this ion retention volume are empirically determined for both axial and radial ion injections and a detailed explanation of the ion retention volume as a function of ion position is provided. In addition, we demonstrate the relationship between ion retention volume and ion kinetic energy. This work demonstrates that sudden-onset rf injection is ideally suited for use with pulsed ionization sources and auxiliary ion bunching devices.