Ion Trap Mass Analyzer Research Articles

Optimization of Linear Ion Trap Mass Analyzer with Triangular Electrodes by Simulation

Abstract As a novel linear ion trap, the triangular-electrode linear ion trap (TeLIT) has simple structure and good analysis capacity. To enhance the analysis capacity of TeLIT, the relationship between its geometry and performance was investigated, and the ion trajectories and mass peaks of TeLIT with different ratio of field radius (rx/ry) was analyzed using simulation software SIMION and AXSIM. The results showed that the analytical performance of the TeLIT could be enhanced by optimizing rx/ry to improve the internal electric fields distribution. As a result, the optimum mass resolution of the ion with m/z 1892 Th could reach 8387 when rx/ry = 5.75/5 and scan rate was 1500 Th s−1. Meanwhile, the resolution of the mass spectrum was in excess of 23000 when the scan rate was decreased to about 300 Th s−1.

Determination of multipole coefficients in toroidal ion trap mass analysers

In this paper, we present methods to determine multipole coefficients for describing the potential in toroidal ion trap mass analysers. Three different methods have been presented to compute the toroidal multipole coefficients. The first method uses at least square fit (LS) and is useful when we have ability to compute potential at a set of points in the trapping region. In the second method we use the Discrete Fourier Transform (DFT) of potentials on a circle in the trapping region. The third method uses surface charge distribution obtained from the Boundary Element Method (BEM) to compute these coefficients. Using these multipole coefficients we have presented (1) equations of ion motion in toroidal ion traps, (2) the Mathieu parameters in terms of multipole coefficients and (3) the secular frequency of ion motion in these traps. It has been shown that the secular frequency obtained from our method has a good match with that obtained from numerical trajectory simulation.

Studying mass spectrometric behaviors of {Au6 Ag2 (C)[PPh2 (4-CH3 -Py)]6 }(BF4 )4 and {Au8 [(PPh3 )2 O]3 (PPh3 )2 }(NO3 )2 by electrospray time-of-flight mass spectrometry and electrospray ion trap mass spectrometry.

Mass spectrometry (MS) has been recognized as a powerful technique to detect accurate chemical information about metal clusters. Maintaining metal clusters intact, which is a great challenge in MS analysis, was achieved in this work by choosing a suitable mass analyzer and carefully optimizing analysis parameters. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) and electrospray ion trap mass spectrometry (ESI-IT-MS) were applied to characterize the synthesized ligand-protected metal clusters [Au6 Ag2 (C)(L(1) )6 ](BF4 )4 (L(1) =2-diphenylphosphanyl-4-methylpyridine) (1) and [Au8 (L(2) )3 (L(3) )2 ](NO3 )2 (L(2) =bis(2-diphenylphosphinophenyl)ether, L(3) =triphenyl-phosphane) (2). Three kinds of buffer gas (helium, mass: 2; nitrogen, mass: 28; argon, mass: 40) and various radiofrequency (RF) amplitudes (from 70 to 330) were chosen to study the fragmentation rate during the "collision cooling" process in the ion trap analyzer. In the ESI-TOF-MS analysis, metal clusters 1 and 2 were mainly observed as intact clusters, which were Au6 Ag2 (C)(L(1) )6 (BF4 )2 (2+) , Au6 Ag2 (C)(L(1) )6 (BF4 )(3+) , Au6 Ag2 (C)(L(1) )6 (4+) for 1 and Au8 (L(2) )3 (L(3) )2 (2+) for 2. While, in the ESI-IT-MS analysis, only fragments could be found, such as Au6 Ag(C)(L(1) )6 (BF4 )(2+) , Au6 (C)(L(1) )6 (2+) , Au5 Ag(C)(L(1) )4 (2+) , Au6 Ag(C)(L(1) )6 (3+) , Au(L(1) )(+) for 1 and Au8 (L(2) )3 (L(3) )(2+) , Au8 (L(2) )3 (2+) , Au6 (L(2) )3 (2+) for 2. It is obvious that the two kinds of mass analyzers caused different MS behaviors of metal clusters. In the ion trap (IT) mass analyzer, particularly, "collision cooling" was contributing to further dissociation of fragile compounds, in which a higher RF amplitude and a larger mass buffer gas led to more fragmentation. In this work, intact metal clusters were obtained in ESI-TOF-MS, instead of ESI-IT-MS, in which the "collision cooling" process caused more cluster dissociation. It was concluded that the analyzer in ESI-TOF-MS is "softer" than that in ESI-IT-MS for metal clusters. Copyright © 2016 John Wiley & Sons, Ltd.

Additive Manufacturing Design and Fabrication of Ceramic Cylindrical Ion Trap Mass Analyzer Chips for Miniaturized Mass Spectrometer Smart-Device (Internet of Things) Applications

The current computing power and network capabilities of handheld smart devices is helping to drive the development of new sensors, enabling the Internet of things. A chip-based mass spectrometer technology promises to offer a smart-device autonomous microsystem chemical analysis capability for sample determination and process monitoring for multiple applications in a small low-power instrument package. This project focuses on the development of cylindrical ion trap (CIT) mass analyzer chips fabricated using three-dimensional (3-D) additive manufacturing (AM) and planar low temperature cofired ceramic thick film processes for a chip-based mass spectrometer microsystem. The CIT is a mass analyzer composed of planar electrodes and operates by trapping and ejecting sample ions based on their mass in a radiofrequency field. Because of its simplicity, CITs may be easily miniaturized and connected in tandem to achieve multiplexing. AM materials and methods enable enhanced trap miniaturization through micromachining and electrode patterning methods, fast and cost-effective prototyping, batch fabrication, and material formulation flexibility. The current design incorporates three parallel ceramic plate metalized electrodes making up a singular trap geometry in a 10-mm2 ceramic chip, forming a mass analyzer of reduced size, mass, and power, with enhanced material robustness for extended range use and in harsh environments. Unique processes have been developed to produce these devices which include conformal metallization layers, adhesion layers, ceramic paste formulations, sacrificial supporting materials, and cofiring methods. Additionally, 3-D printing brings a unique design and fabrication capability enabling novel structures, material blending, and heterogeneous integration. With true digital control, the designs are easily scalable and shape agnostic.

Structure and Property of Ladder Electrode Linear Ion Trap Mass Analyzer

Abstract The theoretical simulation and optimization of a new linear ion trap mass analyzer-ladder electrode ion trap mass analyzer (LeLIT) was described. The LeLIT was consisted of two pairs of ladder electrodes and one pair of end-electrodes. Compared with conventional rectilinear ion trap (ReLIT) which is built with plate electrodes, LeLIT can adjust and optimize the electric field distribution to obtain optimal performance. Meanwhile, the structure of LeLIT is more similar to the geometrical structure of hyperbolic electrode than that of ReLIT, but it is much easier for processing compared with hyperbolic electrode. According to the simulation results, the optimization of electric field distribution inside the ion trap could be realized through adjusting its geometric parameters such as height, width and field radius ratio of ladder electrodes, which was expected to further optimize the mass spectrometry performance of ion trap. As indicated by theoretical simulation results, mass resolution of 10150 at the scanning speed of 225 Da s−1 was obtained with a LeLIT (dimension of X0 × Y0 = 9 mm × 5 mm). LeLIT can significantly improve the mass resolution while maintaining its simple structure. As indicated by the preliminary experiment results, LeLIT has a good analyzing performance as tandem mass spectrometry.

High Pressure Mass Spectrometry: The Generation of Mass Spectra at Operating Pressures Exceeding 1 Torr in a Microscale Cylindrical Ion Trap.

We present the first demonstration of high pressure mass spectrometry (HPMS), which we define as mass spectrometry performed at pressures greater than 100 mTorr. Mass analysis is shown at operational pressures exceeding 1 Torr of helium buffer gas. A differentially pumped MS system was constructed for HPMS development consisting of two chambers. The first chamber (mass analysis chamber) was operated at pressures up to 1.2 Torr and contained the ionization source and a microscale cylindrical ion trap (CIT) mass analyzer. The CIT had critical dimensions of r0 = 500 μm and z0 = 650 μm. The second chamber was held at a lower pressure (≤10 mTorr) and contained an electron multiplier for detection. Mass spectra for xenon, 2-chloroethyl ethyl sulfide (CEES), and octane were acquired with helium buffer gas pressures ranging from 0.04 to 1.2 Torr in the mass analysis chamber. Full-width at half-maximum of mass spectral peaks was found to increase 143% for xenon, 40% for CEES, and 77% for octane over this pressure range, with maximum peak widths of 1.19, 1.26, and 0.82 Da, respectively. Data were fitted with an algebraic model that factors in ion-neutral collision peak broadening effects at high pressures. Experimental and theoretical peak broadening slopes showed good agreement at buffer gas pressures greater than 0.2 Torr. Experiments presented here demonstrate mass spectrometry at pressures orders of magnitude higher than conventionally practiced with any type of mass analyzer. The use of HPMS provides a way to eliminate turbo pumping requirements, leading to significant reduction in MS system size, weight, and power and facilitating a path toward compact/hand-held mass spectrometers with numerous potential applications.

Optimization of Performance of Toroidal Ion Trap with Trianglar Electrode by Theoretical Simulation

Abstract Owing to the ion storage capacity far superior to that of three-dimensional ion trap of the same volume, toriodal ion trap is deemed to be another useful candidate of miniaturization of ion trap mass analyzer in recent years. To further optimize the performance of mass spectrometry of toriodal ion trap, especially the ion detection efficiency and the mass resolving power, a new toriodal ion trap built with triangular electrodes was proposed and investigated theoretically. The new toroidal ion trap was composed of two identical ring electrodes with triangular cross section and two cylindrical electrodes of different sizes. Ions were extracted from the ion trap through resonance excitation for mass analysis. The asymmetrical triangular electrode structure was obtained through theoretical simulation and optimization of ion detection efficiency and mass resolving power. The mass resolution (M/ΔM) of ∼1500 at m/z 609 was obtained for a toriodal ion trap with an optimal electrode structure.

Stability Diagrams for Paul Ion Traps Driven by Two-Frequencies

In this paper, we present and discuss stability diagrams for Paul traps driven by two ac voltages. In contrast to a typical Paul trap, here we suggest a secondary ac voltage whose frequency is twice the frequency of the primary one. The ratio between their amplitudes can be used to expand the region of stability and to access different states of motion of trapped ions. This provides a further mechanism to trap, cool, and manipulate single ions and also to improve the experimental framework where ion clouds and crystals can be prepared and controlled. Such approach opens the possibility of designing more sophisticated trapping architectures, leading to a wide variety of applications on ion trap research and mass analysis techniques.

Trace analysis of sulforaphane in bee pollen and royal jelly by liquid chromatography-tandem mass spectrometry.

In this study, we investigate for the first time the presence of sulforaphane (SFN) residues in two of the most currently consumed food/dietary supplements, royal jelly and bee pollen. Chromatography-tandem mass spectrometry (LC-MS/MS) was the method employed, the mass spectrometer consisting of an ion-trap mass analyzer used with electrospray ionization (ESI) in positive ion mode. An efficient sample treatment involving a solvent extraction with methanol, centrifugation, and concentration in a rotary evaporator was proposed. In all cases average analyte recoveries were between 92 and 106%. Chromatographic analysis (16min) was performed on a core-shell technology based column (Kinetex C18, 150×4.6mm, 2.6μm, 100Å). The mobile phase consisted of 0.02M ammonium formate in water and acetonitrile, with a flow rate of 0.5mL/min in gradient elution mode. The fully validated method was selective, linear from 8 to 1000μg/kg (bee pollen), or from 10 to 1250μg/kg (royal jelly), precise and accurate; relative standard deviation (% RSD) and relative error (% RE) values were below 10%. Low limits of detection (LOD) and quantification (LOQ) were obtained, namely, 3μg/kg (LOD) and 8 (bee pollen) and 10 (royal jelly) μg/kg (LOQ). The method was applied for SFN analysis in several royal jelly and bee pollen samples. SFN was detected at trace levels in some bee pollen samples (<23μg/kg) examined, whilst SFN went undetected in the royal jelly samples analyzed.

Direct Analysis of Nonvolatile Chemical Compounds on Surfaces Using a Hand-Held Mass Spectrometer with Synchronized Discharge Ionization Function.

Synchronized discharge ionization (SDI) was previously developed for hand-held mass spectrometers with discontinuous atmospheric pressure interfaces. The function of SDI has been demonstrated for analysis of volatile organic compounds in air at high sensitivity, which is attributed to the fact that ions were produced next to the ion trap mass analyzer inside the vacuum manifold. In this study, a simple sampling device was designed and fitted to a hand-held mass spectrometer to characterize its potential in direct analysis of low-volatility chemicals on surfaces. Nine chemicals of vapor pressures ranging from 10(-4) to 10(-8) Torr (at room temperature), including pesticides, illicit drugs, and explosives, were selected to evaluate and demonstrate the analytical capability of the designed system. Compounds of vapor pressures below 10(-7) Torr, such as tetryl, cocaine, and tetrahydrocannabinol (THC), have been successfully detected. Direct analysis of pesticides from fruit and explosives from a large surface area has also been demonstrated. Tandem mass analysis was performed, which helped to confirm the analyte identity as well as to improve the signal-to-noise ratio (S/N).

Real Time Online Correction of Mass Shifts and Intensity Fluctuations in Extractive Electrospray Ionization Mass Spectrometry.

Real time online calibration of mass shift and intensity fluctuation to improve the accuracy of measurements for identification and quantitation in trace mass spectrometric analysis was demonstrated using extractive electrospray ionization mass spectrometry (EESI-MS). The signals of authentic compounds (e.g., lysine (Lys), proline (Pro), and histidine (His)) spiked into the extractive solution for the EESI process were used as the references to calibrate the signal of analytes (e.g., methionine (Met)) in the untreated sample solution. The intensity of the analyte signal was recorded simultaneously with the reference signals. The analyte signals at a given time point were calibrated on the basis of these correlation factors and real time signal response of the reference. The calibrated signal of Met at 10 μg L(-1) was improved with a better signal-to-noise ratio (S/N from 2.3 to 4.3), better linearity (R(2) from 0.9758 to 0.9980), and reduced relative standard deviation (RSD from 9.8% to 6.0%). The shift of mass-to-charge ratio of Met signal between the detected and theoretical values was decreased from 247 ± 133 to -7 ± 167 ppm for 50 min of detection using a linear ion trap mass analyzer and was reduced from -0.27 ± 0.60 to -0.12 ± 0.23 ppm for 50 min of detection using an Orbitrap mass analyzer (P = 95%). This method has been validated using a certified standard amino acids solution (GBW(E)100062) and applied for quantitative detection of amino acids in chicken feed, urine, nutritional drink, and facial mask samples, showing that the method is useful to improve the accuracy of mass spectrometric analysis.

Linear ion trap with added octopole field component: the property and method.

It is well known that superimposition of some positive octopole field will benefit the performance of ion trap mass analyzer. In the radial-ejection linear ion trap (LIT), adding some octopole field component to the main quadrupole field is usually accomplished by stretching the ejection rod pair. In this study, the effect of octopole potential and some other higher order potential on the performance of LIT mass analyzer is investigated. A simple and effective method, which is to add some octopole component by building a LIT with a pair of rectangular electrodes and a pair of semi-circular electrodes, is reported. Its properties were studied by numerical simulations and experiments. The results showed that a certain amount of positive octopole component could be produced by simply adjusting the position and width of the rectangular electrodes. A resolution of over 1200 at m/z 609 (~1600 Da/s) was observed in this type of LIT. They also performed tandem mass spectrometry well. The device with optimum geometry for ion ejection from rectangular electrodes provided comparable performance to that for ion ejection from semi-circular electrodes. This type of LIT design is easy for fabrication and assembly.

Hydrophilic interaction liquid chromatography–electrospray ionization-tandem mass spectrometry of a complex mixture of native and oxidized phospholipids

A mixture of native and oxidized phospholipids (PLs), generated by the soybean lipoxygenase type V-catalyzed partial oxidation of a lipid extract obtained from human platelets, was analyzed by Hydrophilic Interaction Liquid Chromatography-ElectroSpray Ionization-Tandem Mass Spectrometry (HILIC–ESI-MS/MS). The complexity of the resulting mixture was remarkable, considering that the starting lipid extract, containing (as demonstrated in a previous study) about 130 native PLs, was enriched with enzymatically generated hydroperoxylated derivatives and chemically generated hydroxylated forms of PLs bearing polyunsaturated side chains. Nonetheless, the described analytical approach proved to be very powerful; indeed, focusing on phosphatidylcolines (PCs), the most abundant PL class in human platelets, about fifty different native/oxidized species could be identified in a single HILIC–ESI-MS/MS run. Low-energy collision induced dissociation tandem MS (CID-MS/MS) experiments on chromatographically separated species showed single neutral losses of H2O2 and H2O to be typical fragmentation pathways of hydroperoxylated PCs, whereas a single H2O loss was observed for hydroxylated ones. Moreover, diagnostic losses of n-hexanal or n-pentanol were exploited to recognize PCs hydroperoxylated on the last but five carbon atom of a ɷ-6 polyunsaturated side chain. Despite the low resolution of the 3D ion trap mass analyzer used, the described HILIC–ESI-MS/MS approach appears very promising for the identification of oxidized lipids in oxidatively stressed complex biological systems.

Additive Manufacturing Design and Fabrication of Ceramic Cylindrical Ion Trap Mass Analyzer Chips for Miniaturized Mass Spectrometer Smart-Devices

A chip based mass spectrometer technology promises to offer smart-device autonomous microsystem chemical analysis capability for sample determination and process monitoring for multiple applications in a small low power instrument package. This project focuses on the development of cylindrical ion trap mass analyzer chips fabricated using 3D Additive Manufacturing and planar Low Temperature Co-Fired Ceramic thick film processes toward the realization of a chip based mass spectrometer microsystem. The cylindrical ion trap (CIT) is a mass analyzer comprised of planar electrodes and operates by trapping and ejecting sample ions based on their mass in an RF field. Because of its simplicity CITs may be easily miniaturized and connected in tandem to achieve multiplexing. Additive manufacturing materials and methods enable enhanced trap miniaturization through micro machining and electrode patterning methods, fast and cost effective prototyping, batch fabrication, and material formulation flexibility. The current design incorporates three parallel ceramic plate metalized electrodes making up a singular trap geometry in a 10mm2 ceramic chip, forming a mass analyzer of reduced size, mass, and power, with enhanced material robustness for extended range use and in harsh environments. Unique processes have been developed to produce these devices which include conformal metallization layers, adhesion layers, ceramic paste formulations, sacrificial supporting materials, and co-firing methods. Additionally, 3D printing brings a unique design and fabrication capability enabling novel structures, material blending and heterogeneous integration. With true digital control, the designs are easily scalable and shape agnostic.

Optimum Radius Size between Cylindrical Ion Trap and Quadrupole Ion Trap

Quadrupole ion trap mass analyzer with a simplified geometry, namely, the cylindrical ion trap (CIT), has been shown to be well-suited using in miniature mass spectrometry and even in mass spectrometer arrays. Computation of stability regions is of particular importance in designing and assembling an ion trap. However, solving CIT equations are rather more dif- ficult and complex than QIT equations, so, analytical and matrix methods have been widely used to calculate the stability regions. In this article we present the results of numerical simulations of the physical properties and the fractional mass resolu- tions of the confined ions in the first stability region was analyzed by the fifth order Runge-Kutta method (RKM5) at the optimum radius size for both ion traps. Because of similarity the both results, having determining the optimum radius, we can make much easier to design CIT. Also, the simulated results has been performed a high precision in the resolution of trapped ions at the optimum radius size.

Determination of aminoglycosides in honey by capillary electrophoresis tandem mass spectrometry and extraction with molecularly imprinted polymers

A new analytical method based on capillary zone electrophoresis-tandem mass spectrometry is proposed and validated for the identification and simultaneous quantification of nine aminoglycosides in honey samples. Detection using an ion trap mass analyzer operating in the multiple reaction monitoring mode was used. Different parameters were optimized in order to obtain an adequate separation combined with the highest sensitivity. In order to achieve high selectivity in the sample treatment, a commercially-available molecularly imprinted polymer has been used for the solid phase extraction of the analytes. Under optimum conditions, recoveries for fortified samples ranged from 88.2 to 99.8%, with relative standard deviations lower than 8%. The limits of detection ranged from 0.4 to 28.5 μg kg−1. Furthermore, the decision limit and the detection capability were evaluated, ranging from 3.5 to 60.5 μg kg−1 and from 6.0 to 103.1 μg kg−1, respectively, demonstrating the sensitivity and applicability of this fast and simple method.

Computer Modeling of an Ion Trap Mass Analyzer, Part I: Low Pressure Regime.

We present the multi-particle simulation program suite Computational Ion Trap Analyzer (CITA) designed to calculate the ion trajectories within a Paul quadrupole ion trap developed by the Jet Propulsion Laboratory (JPL). CITA uses an analytical expression of the electrodynamic field, employing up to six terms in multipole expansion and a modified velocity-Verlet method to numerically calculate ion trajectories. The computer code is multithreaded and designed to run on shared-memory architectures. CITA yields near real-time simulations with full propagation of 26 particles per second per core. As a consequence, a realistic numbers of trapped ions (100+ million) can be used and their trajectories modeled, yielding a representative prediction of mass spectrometer analysis of trace gas species. When the model is compared with experimental results conducted at low pressures using the conventional quadrupole and dipole excitation modes, there is an excellent agreement with the observed peak shapes. Owing to the program's efficiency, CITA has been used to explore regions of trapping stability that are of interest to experimental research. These results are expected to facilitate a fast and reliable modeling of ion dynamics in miniature quadrupole ion trap and improve the interpretation of observed mass spectra. Graphical Abstract ᅟ.

Recent Advances in the Study of the Inclusion Complex Darunavir-β-Cyclodextrin by LC-MS.

Darunavir is a protease inhibitor used in the treatment of human immunodeficiency virus (HIV) infection. This work proposes a LC-MS method indicative of stability for the determination of darunavir in the complex darunavir-β-cyclodextrin, a recent advance for the use of antiretroviral. The method was completely validated according to the International Conference on Harmonization guidelines, showing accuracy, precision, selectivity, robustness, and linearity. The separation was achieved on a 250 mm × 4.6 mm CN Luna column with water +0.1% glacial acetic acid-acetonitrile +0.1% glacial acetic acid, 60 + 40 (v/v) at phase at a flow rate of 1.0 mL/min. UV detection was performed at 268 nm at 25°C. Mass spectral analyses were performed with electrospray ionization ion source and ion trap mass analyzer. The method was linear over the concentration range of 10-60 μg/mL with correlation coefficients at 1.000 and LODs and LOQ of 1.13 and 3.43 μg/mL, respectively. The drug for HIV infection was subjected to acid, basic, oxidative, and neutral degradation and photolysis. Degradation products were identified by LC-MS and LC-tandem MS; therefore, the method can be regarded as indicative of stability. The validated method is very useful to the routine quality control for quantification of darunavir in inclusion complex darunavir-β-cyclodextrin.

Rapid Mass Analysis of Reserpine and Arginine by Ion Trap Mass Spectrometer

Abstract A fast mass analysis method using digital ion trap technology was reported. The mass analysis was realized by scanning the frequency of digital RF voltage and dipole ion resonance voltage during ion injection period without the conventional ion cooling, ion resonance ejection or ion cleaning process. It can decrease about three fourth of traditional analysis time using ion trap mass spectrometry. The ion signal was optimized through the modification of frequency scanning rate, ion gate voltage and other experimental parameters. For example, an optimal mass spectroscopy of reserpine ( m / z 609) and arginine ( m / z 174) were obtained when the ion gate voltage was 9 V and the digital RF frequency was scanned from 1 MHz to 400 kHz at rate of 2385 Th s −1 . The results indicated that the obtained mass spectra were in very good agreement with conventional analytical method using ion trap mass analyzer.

Design and performance evaluation of a linear ion trap mass analyzer featuring half round rod electrodes.

A novel linear ion trap mass analyzer featuring half round rod electrodes (HreLIT) has been built. It is mainly composed of two pairs of stainless steel electrodes which have a cross-section of half round rod and a pair of end electrodes. The HreLIT has a simple structure and so it could be assembled by hand with relatively high mechanical accuracy. The external dimension of HreLIT is 50mm × 29.5mm × 28mm (length × width × height) and its internal volume is about 3.8cm(3). A home-made HreLIT mass spectrometer with three-stage vacuum system was built and the performance of HreLIT was characterized using reserpine solution and PPG standard solution. When the scan rate was 254u/s, mass peak with FWHM of 0.14u was achieved for ions with m/z 609, which corresponds to a mass resolution of 4350. The HreLIT was also operated at a low q value of 0.28 to extend its mass range. The experiment result showed a mass range of over 2800u and the amplitude of radio frequency (rf) signal was only 1560V (0-p). Three-stage tandem mass spectrometry was successfully performed in the HreLIT, and the collision-induced dissociation (CID) efficiencies of MS(2) (CID of ions with m/z 609) and MS(3) (CID of ions with m/z 448) were 78% and 59%, respectively.