Design and performance of a novel hybrid mass spectrometer is described. It couples a linear ion trap mass spectrometer to an orbitrap mass analyzer via an rf-only trapping quadrupole with a curved axis. The latter injects pulsed ion beams into a rapidly changing electric field in the orbitrap wherein they are trapped at high kinetic energies around an inner electrode. Image current detection is subsequently performed after a stable electrostatic field is achieved. Fourier transformation of the acquired transient allows wide mass range detection with high resolving power, mass accuracy, and dynamic range. The entire instrument operates in LC/MS mode (1 spectrum/s) with nominal mass resolving power of 60,000 and uses automatic gain control to provide high-accuracy mass measurements, within 2 ppm using internal standards and within 5 ppm with external calibration. The maximum resolving power exceeds 100,000 (fwhm). Rapid, automated data-dependent capabilities enable real-time acquisition of up to three high-mass accuracy MS/MS spectra per second.
An ion rotating excitation mode of operation of a segmented gas-filled radio-frequency quadrupole (RFQ) ion guide for a high-resolution orthogonal time-of-flight (TOF) mass spectrometer is described. It is shown theoretically, by computer simulation and experimentally, that ion rotating excitation in a gas-filled RFQ has several advantages over other types of ion oscillation excitation. The main advantages are an approximately twofold increase in average ion kinetic energy for the same maximal deviation from the RFQ axis and therefore an increase of about this factor of average internal excitation energy of ions, and the extended mass range of fragment ions that can be observed. The new method of ion decomposition by ion rotation around the axis of an RFQ ion guide was experimentally implemented and tested using a home-built`SIN-COS' generator to supply the excitation voltage. This generator enables control of phase shift and amplitude of excitation voltages applied to quadrupole rods smoothly from the data acquisition program running on a PC. Copyright # 2001 John Wiley & Sons, Ltd.As a result of the orthogonal injection of ions, 1,2 the coupling of electrospray ionization (ESI) to time-of-flight mass spectrometry (TOFMS) has now become an attractive technique, especially for structural investigation of biomolecules. Tandem mass spectrometry (MS/MS) capabilities in this case are very important and, within the last few years, the literature on ESI-TOFMS has begun to focus on MS/MS techniques with hybrid instruments. Commonly, fragmentation of ions in these systems is achieved by traditional methods for collision-induced dissociation (CID). 3±5 However, a collision cell which is often also a radio-frequency ion guide provides the intrinsic possibility of inducing of collision-induced fragmentation of selected ions by resonant excitation of ion oscillations at the auxiliary angular frequency:where q M is the Mathieu parameter, o is the fundamental angular radio frequency (RF) of the voltage applied to the quadrupole ion guide (collision cell), q is the ion charge, m is its mass, V rf is RF-amplitude, and r 0 is the radius of the radiofrequency quadrupole (RFQ), i.e. the minimal distance from axis to rods. These oscillations may be considered on average as harmonic due to the quadratic dependence of averaged effective RFQ potential (or ion`potential' energy) on the distance r av from the RFQ axis:where t v is the ion velocity relaxation time, and F is the maximal field strength at the considered point. The last approximate equality is valid for low enough gas pressure in the RFQ (when ot v ) 1) and in the vicinity of its axis. The motion of an ion in the RF-only quadrupole ion guide can be excited through the application of an auxiliary voltage on one set of pole pairs (dipolar excitation) or on two sets of these (quadrupolar excitation). In the presence of a background neutral gas, the excited ion motion will result in an increase in the number and energy of collisions. As kinetic energy is transferred to ion inter...
The rapidly increasing adoption of high-resolution accurate-mass methods in analytical laboratories has fueled demand for instruments that combine high performance and reliability with small size and greater ease-of-use. This paper presents the major design principles that are driving the evolution of the hybrid quadrupole-Orbitrap instrument architecture to enable a greater range of applications and users. These principles may be summarized as follows: better usage of physical space and better access for service by means of size reduction of pumping and ion optics; expanded use of technologies from electronics in ion-optical design; flexibility in performance via modularity of design of the hardware and software components; and, harmonization of interfaces with other instruments to facilitate sharing and transferability of analytical workflows. The design of a novel family of hybrid mass spectrometers is described in detail, and performance evaluation is carried out on a wide variety of samples for its three representatives: the Orbitrap Exploris 120, Orbitrap Exploris 240 and Orbitrap Exploris 480 mass spectrometers.The new instrument family is shown to offer compelling potential not only for high-end proteomics and biopharmaceutical applications, but also for screening, trace, targeted and clinical analysis by liquid chromatography/mass spectrometry methods.
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