Abstract

From Conventional Mass Analyzers to Modern Hybrid Instruments

Juergen Gross, Head Mass Spectrometry Lab, Heidelberg University

Mass analyzers represent the core of any mass spectrometer. From the beginnings of mass spectrometry they have undergone a tremendous development. Starting from devices that employed a single principle of mass analysis at a time they have evolved to sophisticated configurations uniting different devices for ion collecting, ion focusing, and ion guiding prior to mass analyzing and eventually ion selecting stages. This talk starts with a compact overview of the various types and concepts of mass analyzers, i.e., magnetic sector (B), linear quadrupole (Q), linear quadrupole ion trap (LIT), three dimensional quadrupole ion trap (QIT), time-of flight (TOF), Fourier transform ion cyclotron resonance (FT-ICR), and Orbitrap. It discusses their respective underlying principles and outlines some basic properties of these analyzers before combinations of these elements are dealt with. The first impact in resolution and mass accuracy was achieved by the double-focusing magnetic sector instrument as devised by Mattauch and Herzog in 1934. From there, numerous variations of analyzers with combined magnetic and electric fields rapidly evolved. The next step was taken by attaching linear quadrupole mass filters as a second stage of tandem MS instruments. The capabilities of these so-called hybrid instruments was convincing and paved the road to ever developing advanced combinations of various stages. State-of-the-art mass spectrometers employ ion funnels to transmit and focus as many ions as possible from the ion source into the mass analyzer. They combine linear quadrupoles with time-of-flight or linear quadrupole ion trap analyzers, and offer tandem MS in different modes of operation. The final stage of mass analysis is often capable of high resolving power and impressing mass accuracy while preceding steps are designed with priority on speed and efficient ion transmission. Furthermore, traditional concepts of mono-directional ion motion along an instrument axis are now bein