Mass Analysis at the Advent of the 21st Century

Abstract

There have been many new and exciting developments in mass spectrometer systems in recent years. Many of these developments are being driven by challenges presented by molecular biology. The activity is fueled by resources being devoted to drug development, for example, and other medically and biologically related activities. Progress in these applications will be accelerated by improved sensitivity, specificity, and speed. In mass spectrometry, this translates to greater mass resolving power, mass accuracy, mass-to-charge range, efficiency, and speed. It is safe to say that the demands resulting from current analytical needs are likely to be met to varying degrees but probably not by a single analyzer technology or hybrid instrument. On-line and/or off-line separations and manipulations combined with mass spectrometry will also play increasingly important roles. For any analyzer, or combination of analyzers, to become widely used it must have an important application for which its figures of merit are best suited, relative to competing approaches. The relative cost of competing technologies is also an important factor. The mass filter has seen so much use in the past 30 years because its characteristics best fit a wide range of applications. As an example, biological applications, which are currently driving many instrument development activities in mass spectrometry, demand more information, of higher quality, from less material, faster, and at lower cost. Which technologies will dominate biological applications in the coming years is open to speculation. However, in considering the relative merits of today's dominant mass analyzers, areas of opportunity for improvement are apparent. Furthermore, new and more demanding measurement needs are constantly being recognized that will continue to exercise the creativity of the mass spectrometry community.

Orbitrap mass spectrometry: Instrumentation, ion motion and applications

“…The dynamic range of the instrument was also measured as a function of analyte (reserpine) concentration and found to be 10 3 -10 4 , which compares favorably with the dynamic ranges of quadrupole ion traps (QITs) (10 2 -10 3 ) (McLuckey & Wells, 2001) and LIT/FT-ICR (10 3 -10 4 ) (Syka et al, 2004b) instruments. Hu et al (2005) suggested that the dynamic range may be limited by the StQ rather than by the orbitrap.…”

“…These bioanalytical demands were addressed by such hybrid instruments as the quadrupole/time-of-flight (QqTOF, where Q refers to a mass-resolving quadrupole, q to a radio frequency (RF)-only quadrupole or hexapole collision cell and TOF to a time-of-flight mass spectrometer) (Morris et al, 1996) and the linear quadrupole ion trap/Fourier transform ion cyclotron resonance (LIT/FT-ICR) (Syka et al, 2004b) that perform in the high resolution (>10,000) and high mass accuracy (<5 ppm) regimes (Marshall, Hendrickson, & Jackson, 1998;McLuckey & Wells, 2001;Williams et al, 2003). The QqTOF, which can be regarded as a triple quadrupole (QqQ) instrument where the third quadrupole is replaced by an orthogonal TOF, was originally used for rapid de novo peptide sequencing (Shevchenko et al, 1997) but has found application in many areas of research including metabolite (Levsen et al, 2005), nucleic acid (Oberacher, Niederstatter, & Parson, 2005) and glycoprotein (Morris et al, 2007) analysis.…”

Ion Trap Collision-Induced Dissociation of Human Hemoglobin α-Chain Cations

“…Factors known to play important roles in deriving structural information from whole multiply charged proteins include the nature of the activation method, the charge state and polarity of the ion, and mass analyzer characteristics such as mass-to-charge range, mass resolution, and mass measurement accuracy. It is the nature of the ion and the dissociation conditions that determine the potential information available, while the performance characteristics of the mass analyzer [31] determine the extent to which the potential information is extracted via mass measurement. In this report, we describe the charge state dependent dissociation behavior of intact multiplyprotonated apohemoglobin ␣-chain ions over the charge state range of…”

Dipolar DC Collisional Activation in a “Stretched” 3-D Ion Trap: The Effect of Higher Order Fields on rf-Heating

“…Ion trap CID, on the other hand, generally involves tens to hundreds of low electronvolt energy collisions over time frames of a millisecond to hundreds of milliseconds [3,4]. Ion traps are popular tools in part due to the ability to conduct multiple mass selection steps with intervening reactions and are often used as stand-alone instruments or as part of a hybrid tandem mass spectrometer [5].…”