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Electrospray ionization plays a central role in modern analytical chemistry. It is often used in combination with an HPLC system and is able to transfer large molecules, such as proteins and complexes, into the gas phase. A liquid solution containing the analyte is sprayed in a strong electric field. Charged droplets generated by this process release the analyte molecules which can ultimately be analyzed by the mass spectrometer system. However, the exact mechanisms of droplet generation and ion release are still not fully understood and are under investigation. Recent literature puts the focus on droplet disintegration and shows that the analyte ions are not exclusively released from the droplets within the ionization chamber but rather in the whole mass spectrometer system. Previous experiments allow the direct observation of the signatures of fragmented droplets within the analyzer region of a time-of-flight mass spectrometer: An oscilloscope was connected to a secondary electron multiplier which serves as an auxiliary ion detector, located downstream of the orthogonal acceleration stage of a time-of-flight mass spectrometer. The oscilloscope is thus able to monitor the time-resolved ion current in the mass analyzer region. Pulses of extraordinarily high ion currents are observable here which are attributed to aspirated charged droplets. This work provides insights into long-term experiments with this experimental setup. There is a focus on signal stability, in the presence of such droplet signatures. It is apparent that the standby time of the instrument between individual measurements and the time since a switch of the polarity mode, has a significant influence on the signal stability. There are also indications that the observations of droplet signatures and the MS signal stability are correlated. • Signatures of charged droplets aspirated from an ESI source into an MS vacuum system are observable in mass analyzer region. • Ion signal observed in TOF and droplet signature frequency are unstable, they decrease during instrument runs. • Instrument standby time between instrument runs and polarity mode switching leads to recovery of signals. • Charging of surfaces in the instrument possibly leading to long term signal drifts. [ABSTRACT FROM AUTHOR]

Linear ion traps and quadrupole mass spectrometers play vital roles in quantum technologies and classical mass spectrometry respectively. Therefore, such systems with nearly same operational principles, are very well studied both theoretically and experimentally. Despite such vast knowledge base, linear ion traps continue to be an important research topic, particularly the effect of small perturbations from ideal conditions. Here, non-degenerate nonlinear resonances of the ion dynamics in a linear three-segmented round-rod radio-frequency ion trap have been studied. Purposefully designed perturbation from an ideal 4-rod symmetric structure results in additional instabilities in the dynamics of the trapped ions. The weightage of the dodecapole potential increases by an order of magnitude in such an asymmetric setup compared to that present in usual symmetric setup of nearly equivalent geometry. The experimental results are corroborated by ion dynamics simulations with commercial software SIMION. Increased dodecapole potential in the asymmetric structure leads to resolution of the frequency of ion oscillation in two mutually perpendicular directions in the radial plane which is otherwise unresolved in a symmetric structure in absence of dc potential. Such asymmetric linear trap, in principle, finds importance in the study of Coulomb crystal, mass spectrometry and relevant trapped ion dynamics. It also opens up the possibility to remove undesired ion species (often known as dark ion) within a chain of physical qubits. • One middle electrode in a three-segmented linear ion trap is taken of different diameter making the trap setup asymmetric. • Nonlinear resonances appear as non-degenerate in the rf stability diagram. • Weightage of the dodecapole potential is larger by an order of magnitude compared to symmetric setup of equivalent geometry. • Increased dodecapole potential has promising applications in mass spectrometry, dark ion elimination from trapped ion-chain. [ABSTRACT FROM AUTHOR]

Multi-pass zoom-mode methods have been described to extend the flight path and resolving power of multi-reflection time-of-flight mass spectrometers, by deflecting exiting ions back into repeat passes through the analyzer. Such methods have been adapted to the Astral analyzer, with repeated passes through a prism deflector found to compensate resolution-destroying aberrations. Changes to resolution were simulated and experimentally characterized, with more than a doubling of resolving power observed with only a moderate loss of transmission. Further methods are also proposed to eliminate the mass spectrum uncertainty caused by overlapping of signals from ions that have undergone unknown numbers of passes. [Display omitted] • Multi-pass zoom mode extends ion flight path and doubles Astral analyzer resolving power. • Switchable deflector moves analyzer between ion trapping and ion transmitting modes. • Deflection-induced aberrations self-compensate at odd total number of passes. • 80 % transmission retained at 3 passes through the analyzer. [ABSTRACT FROM AUTHOR]

Mass spectrometry imaging (MSI) is a powerful analytical technique for the two-dimensional (2D) localization of chemicals on surfaces. Conventional MSI experiments require to predefine the surface of interest based on photographic or microscopic images. Typically, these boundaries can no longer be changed or adjusted once the experiment has been started. In terms of a more interactive approach we recently developed a pen-like ionization interface which is directly connected to the mass spectrometer. The device allows the user to ionize chemicals by desorption electrospray ionization (DESI) and to freely move the interface over a surface of interest. A mini camera, which is mounted on the tip of the pen, magnifies the desorption area and enables a simple positioning of the pen. The combination of optical data from the camera module and chemical data obtained by mass analysis facilitates a novel type of imaging experiment: interactive mass spectrometry imaging (IMSI). For this application, we present a novel approach for a robust, optical flow-based motion detection. While the live video stream from the camera is used to track the pen's motion across the surface a post-acquisition algorithm correlates the coordinates of the pen trajectory with respective mass spectra obtained from a simultaneous mass spectrometric data acquisition. This algorithm is no longer dependent on a single, manually applied optical marker on the sample surface, which has to be visible on all video frames throughout the analysis. The advanced DESI-IMSI method was successfully tested on inkjet-printed letters as well as mouse brain tissue samples. Validation of the results was done by comparing DESI-IMSI with standard DESI-MSI data. [Display omitted] [ABSTRACT FROM AUTHOR]

A coherent classification of electrospray axial regimes is provided based on non-linear fluid dynamics as revealed by spray current measurements and fast time-lapse imaging of the electrified meniscus. The classification includes two periodic (dripping, pulsating), two transient/chaotic (burst, astable), and two stationary (cone-jet, jetting) regimes. The dripping faucet phase diagram is described as a particular case of a more complex electrospray phase diagram. Spray current measurements and electrospray characteristic curves are presented as essential for the diagnosis of the electrospray operation and the transition between its various regimes. Reaching a consensus on regime nomenclature and a standardized approach to designate transitions between electrospray regimes is suggested. Finally, the effect of the electrospray operating regime on the mass spectrometer signal is briefly summarized. [Display omitted] • Regime nomenclature and labels describing transitions observed in electrospray characteristic curves are suggested. • The dripping faucet is portrayed as a particular case of electrospray. • Research exposing the effect of electrospray regime on mass spectrometry signal is reviewed. [ABSTRACT FROM AUTHOR]

d -Cysteinolic acid (D-CA) is an important metabolite within the biosulfur cycle. A structural isomer, (R)-3-amino-2-hydroxypropanesulfonate ((R)-AHPS), is less common in nature but potentially can be misidentified as D-CA due to their many shared physical properties. To support confident assignment of these two isomers by use of mass spectrometry alone, this study explores the fragmentation reactions of their [ M + H ] + and [ M − H ] − ions using collision-induced dissociation (CID). Electrospray ionization mass spectrometry (ESI-MS) experiments were conducted on authentic standards using an ion trap mass spectrometer, while a triple-quadrupole (QqQ) mass spectrometer was used in the selective reaction monitoring (SRM) mode to record energy-resolved CID. Density-functional theory (DFT) calculations were carried out at the M06/6-31+G* level of theory to study gas-phase fragmentation mechanisms. The data generated revealed kinetically-controlled fragmentations involving participation of neighboring amino groups in the positive ion mode. Negative ion mode MS analysis could distinguish the structural isomers through different collision energy-resolved results for m/z 95 product ions, CH 3 SO 3 −. DFT calculations revealed an enthalpy (Δ H) (Gibbs energy (Δ G)) gap of 31.8 (31.4) kJ/mol between transition state barriers of a concerted mechanism for D-CA, and a more preferred stepwise mechanism for (R)-AHPS. [Display omitted] • MS of isomers d -Cysteinolic acid (D-CA) and (R)-3-amino-2-hydroxypropanesulfonate ((R)-AHPS) are explored. • Low energy CID of [M + H]+ ions cannot distinguish D-CA from (R)-AHPS. • D-CA and (R)-AHPS give the same [M + H–H 2 O]+ aziridinium product ion. • Low energy CID of [M − H]– of D-CA and (R)-AHPS show differences in product ions formed. [ABSTRACT FROM AUTHOR]

In this study, we introduce the design, characterization, and application of an integrated thermal desorption corona discharge ionization (TD-CDI) device, which was developed for direct mass spectrometry (MS) analysis of drugs in solid or liquid samples. The structure and operational parameters of the TD module were optimized through simulation and experimental investigations. For the CDI module, a hollow needle was used as the discharge electrode and sample inlet, allowing self-aspiration and efficient ionization of the desorbed samples. The TD-CDI device was tested and characterized using different mass spectrometers, exhibiting satisfactory stability and quantitative performance. Owing to its compact structure, it can be coupled to a miniature MS instrument to implement rapid identification of various drugs in urine solutions. [Display omitted] • A compact thermal desorption module was coupled to a self-aspiration corona discharge ionization source for drug analysis. • Simulation and experimental methods were combined to optimize various operational parameters. • The TD-CDI device was coupled with both large and miniature mass spectrometers to realizedrug analysis in real samples. [ABSTRACT FROM AUTHOR]

A dual-stage asymmetric ion funnel (DAIF) interface has been designed to remove the bottleneck in ion transmission from atmospheric ionization to the vacuum chamber. This leads to increased sensitivity and improved performance of the mass spectrometer. Both ion funnels are asymmetrically constructed, with a precisely calculated 7 mm radial offset in the ion path. This accelerates the separation of ions from the neutral stream, reduces contamination, and enhances the flow field and vacuum system. The performance of the DAIF interface was investigated through numerical simulations and experimental tests, utilizing the Hexin API-5000 TOFMS as our experimental platform. The results indicate that the asymmetric ion funnel has a powerful desolvation capability, achieving a high transmission efficiency of 87.9%. The novel DAIF interface enhances sensitivity by an order of magnitude. In addition, the robustness of the instrument can be improved by efficiently removing neutral molecules and contaminants from the DAIF. These features make DAIF suitable for various MS systems and ionizations. [Display omitted] • Dual-stage asymmetric ion funnel interface. • High transmission efficiency. • Efficiently removing neutral molecules and contaminants. [ABSTRACT FROM AUTHOR]

Lead (Pb) isotopes have been widely used in isotopic dating and geochemical tracing. The rapid development in Earth sciences requires high precision and accuracy of isotopic measurements of low Pb contents or small amounts of samples. However, low ionization efficiency can significantly affect the sensitivity and precision of the measurement. Emitters, such as silicon dioxide (SiO 2) gel used in the thermal ionization mass spectrometer (TIMS) measurement of Pb isotopes, can reduce Pb loss at the low-temperature stage and improve Pb ionization efficiency at the high-temperature stage, but they inevitably introduce Pb blank and affect the quality of the results. Therefore, the emitters should possess the features of both high ionization efficiency and low Pb blank. In the present study, a SiO 2 gel solution was produced via a double-bottle method and then purified by the Sr-spec® resin. We further measured Pb blank value of this emitter using the isotopic dilution method and examined its ionization efficiency via measuring isotopic composition of standard reference materials of Pb solution and rock powders using different amounts of Pb. Analytical data show that Pb blank values of the twice-purified SiO 2 gel solution are lower than 1 pg/μL (lowest value of ∼0.3 pg/μL). Moreover, it can effectively improve Pb ionization, and maintain high and stable ion signal intensity during the measurement runs. Analytical results of Pb isotopic compositions, obtained from nano- to subnano-gram Pb amounts of reference materials, all fall in the ranges of their reference values, meeting the requirements in precision and accuracy for the measurements on micro-samples. This emitter is useful for Pb isotopic measurement of micro-samples and predictable to promote the application of Pb isotopic geochemistry. [Display omitted] • SiO 2 gel was produced by reaction of SiCl 4 and water with a double-bottle configuration. • Low Pb blank of the gel was obtained via purification of the Sr-Spec® ion exchange resin. • This gel can effectively improve Pb ionization during the TIMS measurement. • The gel emitter ensures Pb isotopic measurement of micro-sample in sub-nanogram level. [ABSTRACT FROM AUTHOR]

CHandra's Atmospheric Composition Explorer-2 (CHACE-2) is a neutral gas mass spectrometer aboard Chandrayaan-2 orbiter. CHACE-2 is a quadrupole based mass spectrometer which detects neutral atoms/molecules in the mass range of 1–300 amu. The data product from CHACE-2 observations provide the partial pressure for different masses that essentially constitute the mass spectra. CHACE-2 scans different masses using suitable voltages such that each mass is contributed by nine mass bins, known as samples. Each spectrum (mass along x-axis and partial pressure along y-axis) is constructed based on these 9 samples, where the fifth sample is expected to be at the center of the peaks. During the actual measurements in space, mass shifts have been observed such that the center of the peaks doesn't coincide with the expected mass bin, but rather shifted to either lower or higher mass bins. Also, the 9 samples that determines the peak shape need not follow the expected pattern. Suitable criteria have been arrived at in order to verify the quality of each spectrum. In view of the large data sets, an algorithm has been developed to determine and calibrate the mass shift, verify the quality of the spectrum based on the criteria and generate suitable flags in the output file. The algorithm is referred to as 'Peak Filter Algorithm'. The output of the algorithm has been validated and the output has been found to be matching with that expected. The details of the algorithm along with the validation results are presented in this paper. The output of the algorithm is significant for the scientific analysis of CHACE-2 data, and also useful for the analysis of data from instruments similar to that of CHACE-2 in future missions. • Algorithm to filter the mass spectra data from CHACE-2 on Chandrayaan-2. • Important for the scientific analysis of data from CHACE-2. • Useful for quality check of mass spectrometer data in future missions. [ABSTRACT FROM AUTHOR]

Infrared ion spectroscopy (IRIS) requires reproducibility and standard protocols in order to be fully appreciated as an analytical tool. An important parameter in IRIS measurements is the infrared laser power (energy per pulse), which is often difficult to control precisely on a day-to-day basis. We have developed an automatic variable attenuator to keep the laser power at a well-defined value, independent of IR frequency and time, while maintaining full overlap of the laser beam with the ion cloud in our quadrupole ion trap mass spectrometer. The device has been used to record IR spectra of the metabolite prostaglandin D2 at different laser pulse energies, allowing us to assess the effects on the IRMPD spectra of excessive ion depletion, a threshold pulse energy below which dissociation is not observed, and unobserved fragments due to electron detachment or fragmentation to below the low mass cut-off of the trap. Image 1 • IRMPD intensities are reproducible when an automatic variable laser attenuator is used to control the laser pulse energy. • IRMPD spectra are recorded as a function of laser pulse energy in a quadrupole ion trap mass spectrometer. • Effects on the IR spectra due to an elevated dissociation threshold and excessive ion depletion are discussed. • Effects due to electron detachment and the formation of fragment ions below the low mass cut-off of the MS are discussed. [ABSTRACT FROM AUTHOR]

The 13C-labelled methionine breath test is a non-invasive test with the potential to evaluate metabolic liver mitochondrial dysfunction in vivo. This study aimed to develop an optimised protocol for breath collection in sheep and compare 13C-methionine and methyl-13C-methionine as substrates for future breath test applications in ruminants. Two doses (1 mg/kg and 2 mg/kg) of 13C-methionine or methyl-13C-methionine in saline were administered via intravenous injection to four South Australian Merino ewes aged three years with an average body weight of 65 kg. Exhaled breath samples were collected at baseline and every 10 min for 180 min after administration of the 13C-labelled substrate, and analysed using an isotope ratio mass spectrometer. Dose recovery of 13CO 2 derived from 13C-methionine was higher at each time-point compared to that derived from methyl-13C-methionine, at both concentrations. 13C-methionine dose evaluation indicated that intra-individual and inter-individual variability of percentage dose recovery was lower in animals dosed with 2 mg/kg 13C-methionine compared to 1 mg/kg 13C-methionine. Mean cumulative percentage dose recovery of animals administered 1 mg/kg and 2 mg/kg 13C-methionine at 60 min, 120 min and 180 min was 5.34 ± 0.87%, 11.52 ± 1.29% and 16.30 ± 1.45%, and 12.30 ± 0.34%, 25.12 ± 0.59% and 34.45 ± 0.57%, respectively. We conclude that the 13C-labelled methionine breath test can be reliably performed in sheep through intravenous administration of 2 mg/kg 13C-methionine. This study also demonstrated the utility and advantage of 13C-methionine compared to methyl-13C-methionine as substrates for future breath testing applications to evaluate hepatic mitochondrial function in sheep and other ruminants. Further development of the test could be employed to evaluate disease progression and efficacy of applied therapeutics in sheep models of human diseases characterised by hepatic dysfunction. In addition, the 13C-methionine breath test could be utilised in animal production to assess hepatic metabolic function and the potential impact of nutritional mismanagement. Image 1 • 13C-labelled methionine is a safe substrate for breath test applications in sheep. • Intravenous substrate delivery yields reliable 13CO 2 detection, bypassing rumen. • Methyl-13C-methionine results in lower 13C recovery compared to 13C-methionine. • 13C-methionine produces more than two-fold increase in detectable 13CO 2. • 2 mg/kg 13C-methionine produces increased output reliability; lower variation. [ABSTRACT FROM AUTHOR]

This work applies the technique of mapping ion detection using a reflectron mass spectrometer against flight-time and reflection voltage to elucidate the complex metastable fragmentation pattern of the biomolecular ion 3-aminophenol+ (3-AP+, C 6 H 7 NO+). Multi-photon ionization experiments revealed the excited ion's fragmentation routes for the first time and comparisons with calculated flight-times enabled 18 different μs-timescale dissociations to be assigned. These included the rare observation of a double hydrogen loss channel from a fragment ion. DFT calculations provided further insights into the most prominent apparent fragmentation sequence: 3-AP+ (m / z 109) → HCO + C 5 H 6 N+ (m / z 80) → CNH + C 4 H 5 + (m / z 53) → C 2 H 2 + C 2 H 3 + (m / z 27). Image 1 • 2D mapping reveals an exceptionally rich metastable dissociation pattern of 3AP+. • Double hydrogen loss has been detected from a fragment ion – a rare observation. • Ab initio calculations elucidated the strongest apparent fragmentation sequence. [ABSTRACT FROM AUTHOR]

Graphical abstract A typical image of C 60 + photoionsmeasured by a high-resolution velocity-map-imaging spectrometer. The photoion energy distribution in the transverse dimension (along the X-axis) can be extracted from the image, indicating that our apparatus has sufficiently high energy resolution to quantify the influence of weak space charge effects on the photoion kinetic energy distribution in a low charge-density regime (107 ions / cm3). Highlights • Proposing an approach to explore the space charge effects involving a low charge densities. • Presenting quantitative information on the space charge effects in the order of 0.1 meV. • Providing a benchmark for estimating the space charge effects in high precision measurements. Abstract We experimentally explore weak space charge effects (SCEs) in multiphoton ionization (MPI) experiments using C 60 as an example of heavy species. The laser-induced delayed ionization of C 60 was used to prepare a photoion pulse with a decreasing initial charge density distribution from a start value that is one order of magnitude smaller than the density limit (3☓108 ions/cm3) proposed previously to assume that the SCEs can be negligible. The photoion spectra at different time slices of the photoion pulse were measured using a velocity map imaging spectrometry. This allows us to quantify the SCEs on the photoion spectra in such low-density and heavy-species regime. The weak SCEs explored here can help us to understand and improve the temporal-spatial resolutions in those high-precision measurements. [ABSTRACT FROM AUTHOR]

Mass spectrometry (MS) is a powerful analytical technology widely used in a broad range of applications. Laboratory-scale mass spectrometers, however, are hardly used outside the analytical laboratories due to the large sizes and weights. Miniature mass spectrometers are therefore developed to facilitate on-site MS analysis. How to stabilize their analytical performances under complex environmental conditions on-site is a challenging problem, which needs to be addressed for the development of miniature MS instrumentation. Here, we report a neural network algorithm which enables automatic mass calibration corrections for a Cell miniature MS system (PURSPEC Technologies Inc.). To simulate the change of complex environmental conditions on-site, variations of temperature from 5 °C to 40 °C, pressure from 98647 Pa to 99406 Pa, humidity from 30 % to 65 %, were employed. The mass accuracy, characterized by the difference between measured mass and nominal mass, after autocorrection of the algorithm was within 0.08 Da. [Display omitted] • The complex environmental conditions on-site have a significant impact on mass accuracy. • A neural network algorithm was developed to correct the mass shift under complex on-site environments. • A test workflow was applied to simulate a real on-site analysis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Peak jitter in SPMS is caused by particle position in the ion source. • Dynamic calibration and time scale adjustment allow to add mass spectra without loss of resolution. • Developed method improve detection limit for trace compounds contained in the particles. • New calibration relation providing mass accuracy increase in comparison to the regular quadratic formula is suggested. Abstract Delay Extraction (DE) in Single Particle Mass Spectrometry (SPMS) provides substantial resolution enhancement. However, DE has two main drawbacks which are discussed in our article. First, ion peak position in this case becomes very sensitive to initial ion coordinate. Therefore, substantial peak jitter is observed when switching between mass spectra of individual particles. This peak jitter obstructs correct mass spectra accumulation resulting in wide peaks with irregular shapes in the accumulated mass spectrum, which leads to the fact that isotopic pattern identification becomes difficult. In the present article two ways of the peak jitter compensation, Dynamic Calibration and Mass Spectra correction based on Spectra Correlation, are proposed. It was shown that both proposed techniques provide substantial resolution improvement in the summed mass spectrum especially for small peaks with complex isotopic patterns. Second, time delay distorts regular quadratic dependence between time-of-flight and m/z. In our paper we also propose calibration equation with variable exponent for SPMS modified with DE. It is shown that usage of an exponent as a fitting parameter allows to achieve mass accuracy comparable with 4th degree equation proposed earlier. [ABSTRACT FROM AUTHOR]

Highlights • The submitted manuscript describes the measurement of mass difference between Pd 102 and Ru 102 performed with the Penning-trap mass spectrometer JYFLTRAP. • A very careful evaluation on the atomic mass difference of the pair Pd 102 – Ru 102 in the Atomic Mass Evaluation based on the analysis of full bulk of spectroscopy information for nearest nuclides showed a dramatic deviation of more than 10 σ with the mass measurement performed at the SHIPTRAP Penning trap. • Since the evaluated mass difference was obtained via numerous local connections in β- and electron capture decays and very precise (n , γ) data which agree with each other perfectly, the reliability of the SHIPTRAP measurement was challenged. • To solve the problem, the measurement of the mass difference Pd 102 – Ru 102 has been undertaken at the JYFLTRAP Penning-trap setup using both the Time-of-Flight and the Phase-Imaging Ion Cyclotron Resonance techniques. • The obtained result is around 8 times more precise and in excellent agreement with the value obtained at SHIPTRAP. This agreement manifests the reliability of the Penning trap mass spectrometry. Abstract The Q -value for the neutrinoless double electron capture on 102Pd, Q ϵϵ (102Pd), is determined as the atomic mass difference between 102Pd and 102Ru. A precise measurement of the Q ϵϵ (102Pd) at the SHIPTRAP Penning trap showed a more than 10 σ deviation to the adopted Atomic Mass Evaluation (AME) value. The reliability of the SHIPTRAP measurement was challenged because the AME value was based on numerous experiments including β and electron capture decays and very precise (n , γ) data, all agreeing with each other. To solve the discrepancy, the Q ϵϵ (102Pd) has now been determined with the JYFLTRAP Penning trap at the IGISOL facility in the Accelerator Laboratory of the University of Jyväskylä. The measurement was performed both with the Time-of-Flight and the Phase-Imaging Ion Cyclotron Resonance techniques. The obtained result, Q ϵϵ (102Pd) = 1203.472(45) keV, is eight times more precise and agrees well with the value obtained at SHIPTRAP, Q ϵϵ (102Pd) = 1203.27(36) keV, confirming that 102Pd is not a good candidate for a search for neutrinoless double-electron capture. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Size selected O 3 −(H 2 O) n and O 2 −(H 2 O) n clusters with n = 0–4 were reacted with CH 3 Cl in the gas phase. • O 2 −(H 2 O) n clusters reacts readily with CH 3 Cl in an S N 2 reaction, O 3 −(H 2 O) n clusters do not. • The computed S N 2 reaction barriers are in accordance with the experimental observations. Abstract Size selected O 3 −(H 2 O) n and O 2 −(H 2 O) n clusters with n = 0–4, produced by electrospray ionization in a corona discharge, were reacted with CH 3 Cl in the collision cell of a quadrupole-time-of-flight mass spectrometer under near thermal conditions. The ozonide–water clusters react primarily by ligand exchange, substituting CH 3 Cl for H 2 O; dehydration due to collisionally induced dissociation is also observed. Only extremely weak signals are observed for the S N 2 reaction between O 3 −(H 2 O) n and CH 3 Cl, yielding Cl−(H 2 O) n−m , also for the naked ozonide (n = 0). This is in contrast to superoxide–water clusters, where the S N 2 reaction with CH 3 Cl occurs readily. High level quantum chemical computations predict energy barriers in accord with the experimental observations, and the difference in nucleophilicity between O 3 − and O 2 − is discussed in light of quantum chemical calculations and Marcus theory. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The design of a prototype thermal ionization cavity (TIC) source installed on a MAT262 mass analyser is presented. • Some key design improvements, e.g. a sectioned cavity design for easier sample loading, are unique. • We have performed a detailed calculation and experimental verification of the ion optics. • First analyses of 1–3 μm diameter uranium oxide particles are very promising. • A ∼10 times improvement in the overall efficiency for uranium analysis compared conventional TIMS has been found. Abstract The design of a prototype thermal ionization cavity (TIC) source attached to the mass analyser of a MAT262 thermal ionization mass spectrometer is presented. In addition to a detailed calculation and experimental verification of the ion optics, the new design includes several innovative features that set it apart from previously reported TIC sources. The goal is to employ this new ion source for high-efficiency isotope ratio analysis. For uranium adsorbed to a single resin bead, an overall efficiency gain of about a factor of 10 compared to the same sample type analysed by state-of-the-art conventional thermal ionization mass spectrometry (TIMS) on a Triton instrument is reported (ions detected per atom loaded). First attempts at isotope ratio analysis of micrometre sized uranium oxide particles, as is commonly done for nuclear safeguards, seem to confirm the enhancement in overall efficiency and could help with the analysis of the minor uranium isotopes on such samples. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • An optimized T-trap with uniform electric field was obtained based on electric field analysis and SIMION simulation. • A high correlation was found between the in-trap electric field gradient distribution and the ion emission characteristics. • Directional ion excitation ability can be achieved with appropriate structure modification. • The finding can be used to implement structure optimization of asymmetric ion trap analyzers. Abstract The toroidal-cylindrical ion trap (TCIT) is a small multi-function tandem ion trap analyzer with a simple structure and a compact design. The asymmetric structure of the out toroidal ion trap (T-trap) confers the in-trap region with a non-uniform electric field distribution, particularly when a plate ring electrode is used. To optimize the electric field distribution in the trap, the shapes of the toroidal electrodes were modified to compensate for the electric field. For this purpose, we developed a simple simulation-based method for evaluating the optimized asymmetric structure of the ion trap electrode. Specifically, static electric field distribution in the trap was acquired using COMSOL software and then simply analyzed, while the SIMION simulation platform was adopted to characterize both the ion motion and the performance of the T-trap with an modified structure. The results revealed that electrode optimization can not only improve the non-uniformity of the in-trap electric field distribution but also implement unidirectional emission of the ions upon resonance excitation, thereby significantly increasing the utilization efficiency of the ions in TCIT. In addition, a high correlation was found between the electric field gradient distribution in the trap and the ion emission characteristics, which can provide an simple but useful guiding significance for the performance and structural optimization of T-trap. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 2122 proteins were identified for S. solfataricus P2. • 48 peptides out of 549 genome search-specific peptides map to 31 new genes. • High resolution MS data demonstrate lysine methylation on the novel protein. Abstract Archaea are well-known for their ability to adapt to harsh environments, which are too severe for the growth of bacteria and Eukaryotes. So far, the studies of Archaea proteomics haven't achieved satisfying proteome coverage yet. In this work, S. solfataricus P2, a typical model Archaea was chosen for proteogenomic analysis to further characterize the proteome. Among 2938 predicted protein-coding genes, 2122 proteins (>72%) were identified. Furthermore, 48 peptides out of 549 genome search-specific peptides were mapped to regions of the genome where no genes were annotated. 31 previously unidentified protein-coding regions were matched by these 48 peptides using FgenesB and 7 of these regions were assigned by at least two unique genome search-specific peptides. Findings in this work suggest the effectiveness of proteogenomics pipeline in expanding the depth of proteome and genome annotation. [ABSTRACT FROM AUTHOR]

A modified post-extraction differential acceleration (PEDA) technique employing two pulsed electrodes was used to demonstrate mass-resolved stigmatic imaging over a broad m / z range. By varying the pulse voltages, a potential energy cusp was introduced into the ion acceleration region of an imaging mass spectrometer, creating two m / z foci that were tuned to overlap at the detector plane. This resulted in two focused m / z distributions that stretched the mass-resolved window with m /Δ m ≥ 1000 to 165 Da without any loss in image quality; a range that doubled the 65 Da achieved under similar conditions using the original PEDA technique. [ABSTRACT FROM AUTHOR]

The kinetic energy that is released upon bond rupture is often represented as T 1/2 . A value that is derived from the FWHM of a fragment peak by the use of two different conversion formulas. The choice of formula depends on whether the peak is recorded by scanning a magnetic sector or an electrostatic analyzer. We have conducted a systematic variation of the possible scan configurations of two different double focusing instruments in two countries. We have found that a double focusing mass spectrometer in normal geometry gives rise to T 1/2 values that are 1.4 times larger when analyzing peaks that are obtained from magnet scans compared to the peaks that are obtained by scanning an electrostatic analyzer. The E scans (MIKE experiments) give rise to the same values for both of the employed mass spectrometers. The results are explained in terms of energy defocusing when the reactions take place too far away from the focal points and show that only the E scans T 1/2 values can be compared from instrument to instrument. [ABSTRACT FROM AUTHOR]

Quadrupole mass spectrometry (QMS) has an important application in the field of rapid on-line analysis of hydrogen isotopes. However, due to the interference of isotope fractionation effect and mass overlap peaks, accurate quantitative analysis of hydrogen isotopes by quadrupole mass spectrometry has always been a challenging problem. For the calibration of a low-resolution quadrupole mass spectrometry, standard samples of hydrogen isotopes gas mixtures with different HD contents were prepared by platinum catalyst that accelerated hydrogen isotope exchange reaction. The results show that the fraction of ionized fragments of various hydrogen isotopes in the mixture is stable and less affected by the coexistence of other isotopes. Taking the main fragment peak as the calibration basis, considering the isotope fractionation effect and mass overlap peak interference, the calibration curve between hydrogen isotope abundance and mass spectral signal was obtained by systematic correction method, and the linear correlation coefficient is 0.9991. The average relative errors between the correction values and the standard values of isotope abundance measured are 1.87% (hydrogen content) and 3.43% (deuterium content), respectively. The method developed in this work can be used for rapid on-line quantitative analysis of hydrogen isotope gas mixtures. [Display omitted] • Pt was used as catalyst to prepare H-D mixed standard samples with different HD contents. • The effect of mixed air intake on the dissociation coefficient of monatomic ions was studied. • The overlap of the peaks of the quadrupole mass spectrum was corrected to obtain the independent partial pressures of different molecules. • The quantitative analysis of the mixture gas of H-D system was realized by using the corrected low resolution quadrupole mass spectrometry. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Detection of larger masses becomes increasingly difficult as the geometrical dimensions of a trap become smaller. • Coplanar traps were developed to investigate limits of ion trap miniaturization. • In spite of a microscale radius, a larger mass range than previous report was demonstrated in a microscale planar linear ion trap (μPLIT). Abstract An extended mass range covering m/z 70–240 in a microscale (r 0 = 800 μm) planar linear ion trap (μPLIT) is demonstrated, enabled by optimization of dipole resonance ejection conditions without increasing trapping voltage or frequency compared with prior results. This represents a significant increase in the measureable mass range of coplanar traps and microscale traps in general. Performance was demonstrated using headspace vapor of octafluorotoluene (OFT) as well as mixture of perflurotributylamine (PFTBA) and OFT. Typical mass resolution of approximately 3 Da (FWHM) was observed. [ABSTRACT FROM AUTHOR]

Previously, we have reported the development of a miniature mass spectrometer with a continuous atmospheric pressure interface, whose sensitivity was sacrificed due to the limited gas flow rate. In this study, a circular lens was designed and integrated on the ion transfer pathway between the two pumping stages, and a ten-fold sensitivity improvement could be achieved when coupling with external ionization sources. Besides the capability of working with ionization sources in the atmosphere, there is also an in-vacuum plasma ionization source, so that both volatile and non-volatile samples could be analyzed. A 10 ppbv detection sensitivity was achieved for dimethyl methyl phosphonate (DMMP) in air using the plasma ionization source. Furthermore, the miniature mass spectrometer was also demonstrated for the direct analyses of progesterone in drinking water and atrazine in soil samples using paper spray and syringe spray, respectively. [ABSTRACT FROM AUTHOR]

It is experimentally challenging to generate and detect nano-sized neutral metal oxide clusters with high-resolution mass spectrometry. Herein, a vacuum ultraviolet (VUV) photoionization time-of-flight (TOF) mass spectrometer based instrument has been home-made to study the generation, distribution, and reaction of nano-sized neutral metal oxide clusters. The VUV laser generation system has been designed to produce four 118 nm laser beams to ionize neutral metal oxide clusters in a supersonic beam with the “head-to-head” style. The TOF mass spectrometer is capable of analyzing nano-sized neutral metal oxide clusters with high mass resolution. Nano-sized neutral manganese oxide clusters Mn m O n ( m = 5–58; n = 8–82) have been generated and the mass resolution ( m /Δ m ) for Mn 41 O 59 (∼1.3 nm) is about 7270. The association products Mn m O n C 2 H 4 can be observed for the reaction of neutral manganese oxide clusters with C 2 H 4 . The rate constants for the reaction of (Mn 2 O 3 ) N ( N = 2–22) with C 2 H 4 have been experimentally determined. [ABSTRACT FROM AUTHOR]

Gas phase decomposition of the ions [M + PbNO 3 ] + (M stands for fluoro-substituted N -nitrophenylaza-crown ether conjugate), has been studied by the electrospray ionization-collision induced dissociation-tandem mass spectrometry (ESI-CID-MS/MS). The conjugates containing hydrogen atom at ortho position to the crown moiety, form abundant fragment ions which can be assigned as complexes of deprotonated conjugates and lead cation, thus the ions [M − H + Pb] + (fragment ions formed as a result of HNO 3 loss). Interaction between the nitro group (present at the second ortho position to the crown moiety) and the metal cation affects the formation of fragment ion [M − H + Pb] + (but does not prevent its formation). Ions [M − H + Pb] + are very rare example of the organometallic species (containing metal-carbon bond), in which metal cation is also complexed by crown ether moiety. [ABSTRACT FROM AUTHOR]

MS/MS sequencing is an unrivaled technique to decipher binary information chemically encoded in the backbone of sequence-controlled synthetic polymers constructed with two co-monomers of different mass, arbitrarily designated as the 0- and 1-bit of the ASCII alphabet. Efficiency of this “reading” step relies however on the simplicity of MS/MS patterns, which depends on both polymer chemistry and chain length. In this context, polyurethanes (PUs) were very promising candidates as dissociation of small deprotonated oligomers (n < 8) yielded a single fragment series. The carbamate bond cleavage reaction was hence studied in details to tentatively anticipate the CID behavior of longer chains prior to optimizing their synthesis. In spite of the simplicity of MS/MS spectra, three different mechanisms were evidenced; however, they were not expected to induce MS/MS complexity when activating longer chains, as verified for sequence-controlled PUs containing up to two bytes of information ( i.e. , 16 co-monomers). In contrast, the ionization step appeared to be an issue: deprotonation yield of the end-group in negative ion mode electrospray was observed to strongly decrease as PU chain length increases. This sensitivity issue was addressed by introducing a second acidic end-group to allow doubly deprotonated oligomers with no impact on their CID behavior. [ABSTRACT FROM AUTHOR]

A method for high-resolution mass selection is presented which makes use of a multi-reflection time-of-flight mass spectrometer with in-trap lift. The new method needs no additional gating or deflection components. The concept is described in detail and demonstrated with both offline and online measurements on short-lived nuclides performed with ISOLTRAP at ISOLDE/CERN. [ABSTRACT FROM AUTHOR]

A method to fractionate and separate nitrogen compounds according to their carbon number is presented here. Typical Brazilian vacuum residue was submitted to solid-phase extraction using a strong cation exchanger to fractionate the basic nitrogen compounds according to their molecular weight. The method described in this paper extended vacuum residue characterization by gradually removing the most basic species that suppress the ionization of compounds with higher mass (and thus less efficiently ionized). Approximately 1393 peaks were assigned when untreated vacuum residue was directly infused into a positive-ion electrospray ionization (ESI(+)) mass spectrometer coupled to Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). In contrast, more than 3500 different nitrogenous elemental compositions were attributed after fractionation. Nitrogen compounds with carbon numbers up to C 100 were detected. Also, new classes (NO, N 2 O, and NOS) of nitrogen compounds were detected after the fractionation. [ABSTRACT FROM AUTHOR]

Sequential ion/ion and ion/molecule reactions are demonstrated in a linear ion trap mass spectrometer and are used to probe the reactivity of metal complexes in unusual ionization states. Taking advantage of the instrument’s electron transfer dissociation (ETD) capabilities, the mono- and bis-phenanthroline complexes of Fe(I), Co(I), Ni(I), Cu(I), and Zn(I) were formed by reduction of the corresponding M(II) species in an ion/ion reaction with the fluoranthene radical anion. The chemistry of the M(I) species was probed in ion/molecule reactions with allyl iodide. The bis-phenanthroline complexes generally give slow reactions and the metals were oxidized to M(II) iodide complexes with presumably the release of allyl radicals. The mono-phenanthroline complexes are much more reactive and give M(II) iodide complexes, M(II) allyl complexes, and adducts. The overall reactivity is in accord with density functional theory calculations and mirrors that of proposed intermediates in condensed-phase catalytic cycles. [ABSTRACT FROM AUTHOR]

The increasing variability of the illicit drug market has imposed serious health risks for people who use drugs (PWUD), particularly due to the increasing co-occurrence of opioids and etizolam (or other benzodiazepines) in some jurisdictions. A miniature mass spectrometer (MS) equipped with paper capillary spray ionization was evaluated for its ability to quantify fentanyl, fluorofentanyl, carfentanil, and etizolam in illicit drug samples. Prior to testing actual drug samples, inter- and intra-day reproducibility, calibration linearity, and analytical sensitivity were assessed. The development of a continuous spray solvent delivery system improved MS/MS quantitation by prolonging ionization stability. A simple, rapid and quantitative tandem mass spectrometry method was developed and employed for the analysis of real-world illicit drug samples provided by PWUD at a harm reduction site in Victoria, British Columbia, Canada. Limits of detection ranged from 0.001 to 0.24% w/w of illicit analyte in the original solid drug samples. Target analytes were detected and quantified via the miniature MS system for samples where conventional on-site drug checking technologies were not always effective. These promising results demonstrate the potential role for miniature mass spectrometer systems for on-site drug checking services that can be both sensitive to trace, toxic levels as well as adaptable/selective for new drug threats as they appear in the illicit drug supply. [Display omitted] • The increased variability of the illicit drug market has imposed serious health risks for people who use drugs (PWUD). • A rapid & quantitative miniature MS method was developed and employed for the analysis of real-world illicit drug samples. • Target analytes were quantified via miniature MS, where other on-site drug checking technologies were not always effective. • Miniature MS systems for on-site drug checking services are sensitive, adaptable and selective for new drug threats. [ABSTRACT FROM AUTHOR]

All fragment ions observed in high-resolution electron ionization (EI) mass spectra of methyl stearate have been completely classified into three different series, such as methyl ester (CnHmO 2), aliphatic hydrocarbon (CnHm) and acylium (CnHmO) ions. From the EI mass spectra classified into aliphatic hydrocarbon series, complementary McLafferty rearrangement (compMcLR) ion at m/z 224 and complementary McLafferty rearrangement+1 (compMcLR+1) ion at m/z 222 were identified from the standpoints of notable intensity and rearrangement reactions. The fragmentation of the keto- and enol-form molecular ions M.+ was discussed on the basis of the sites of unpaired electron (radical) and positive charge, which were determined by the spin density evaluated by density functional theory (DFT). The structure of M.+ determined by DFT rationally indicated that the compMcLR and compMcLR+1 ions at m/z 224 and 222 are produced by charge migration, while the McLR and McLR+1 ions at m/z 74 and 75 are produced by charge retention. The difference in the peak abundance of m/z 74 and 224 ions were evaluated from the difference in the ionization energy of the corresponding neutral fragments, based on Stevenson's rule. [Display omitted] • All fragment ions observed in high-resolution EIMS of methylstearate were completely classified into methylester, aliphatic hydrocarbon and acylium series ions. • Complementary McLafferty rearrangement (compMcLR) ions at m/z 224 and 222 were identified from the reconstructed EI mass spectra of hydrocarbon series ions at 70, 20 and 15eV impact energy. • The compMcLR and compMcLR+1 ions at m/z 224 and 222 could be explained by the charge migration, while the McLR and McLR+1 ions at m/z 74 and 75 could be explained by the charge retention. • The charge-retention/migration reactions and peak abundance for above ions were evaluated from the DFT calculations and Stevenson's rule. • The reaction path involved transition state for the formation of the McLR and compMcLR ions from enol-form was calculated using the global reaction route mapping by the anharmonic downward distortion following (ADDF) method. [ABSTRACT FROM AUTHOR]

Isotope dilution mass spectrometry was used to independently assess the accuracy of mass measurement methods developed to quantitatively dispense milligram quantities of aqueous solution. Solutions of isotopically enriched 158Gd and enriched 155Gd were prepared with the molality (mol g−1) of the 155Gd solution being approximately 400 times more dilute than the 158Gd solution. Aliquots of the 158Gd solution were flame sealed in glass ampoules and the 155Gd solution was quantitatively dispensed as a series of 1-g sample aliquots and larger (45 g–55 g) calibration aliquots. Calibration mixes of the solutions were prepared by mass and the Gd isotopic compositions of the 155Gd, 158Gd, and mixed Gd calibration solutions were measured using a high-resolution multi-collector inductively coupled plasma mass spectrometer. These data were used to calculate an elemental amount ratio for Gd in the solutions. Several 155Gd solution sample units were then spiked with small aliquots (0.25 mg–6 mg) of 158Gd solution for which the masses were determined using glass microcapillary and inkjet dispensing methods. The measured Gd isotopic compositions of these mixed solutions, along with the previously calibrated Gd elemental amount ratio and the known masses of the 155Gd aliquots, were used to calculate masses of dispensed 158Gd solution samples. These isotope dilution-based mass measurements have relative expanded uncertainties <0.1% (k = 2), which will allow solution masses measured by microcapillary and inkjet dispensing methods to be assessed for accuracy. [Display omitted] • Measuring mass of sample matrices by isotope dilution mass spectrometry. • Low uncertainty determination of mass for milligram size solution samples. • Verification of small solution aliquots weighing methods at < 0.1% uncertainty. [ABSTRACT FROM AUTHOR]

The increasing prevalence of designer drugs has contributed towards the adoption of rapid screening techniques, such as direct analysis in real time-mass spectrometry (DART-MS). Recently, the National Institute of Standards and Technology (NIST) developed a DART-MS Forensics Database and Data Interpretation Tool (DIT) to assist practitioners with the interpretation of seized drug mixtures. However, this resource was only designed for DART ionization coupled with AccuTOF high-resolution mass spectrometers. This study assesses the effectiveness of the NIST DART-MS Forensics Database and DIT for mixture interpretation using other soft ionization sources, such as electrospray ionization (ESI), and coupling DART to an Agilent 6530 quadrupole time-of-flight (Q-TOF) mass spectrometer. As the seized drug community continues to shift towards the use of in-source collision-induced dissociation (IS-CID) with single-stage mass spectrometers coupled with soft ionization sources, it is imperative to understand the similarity of the generated IS-CID fragment ion spectra and the effectiveness of the DIT for seized drug screening using instrumentation other than the DART-AccuTOF. Pearson product-moment correlations (PPMCs) revealed a high degree of spectral similarity between the ESI-IS-CID and DART-IS-CID fragment ion spectra collected across a range of activation conditions. The 95% confidence interval for the average highest PPMC coefficient across the 12 designer drugs in this study was 0.9295 ± 0.0031. More importantly, nearly identical mixture interpretation results were obtained when the ESI-IS-CID and DART-IS-CID fragment ion spectra were analyzed with the DIT. In all cases, the DIT was able to identify a potential library match with at least two match types between the low and high IS-CID spectra for all compounds present in each mixture. Demonstrating the potential applicability of the NIST DART-MS Forensics Database and DIT for the screening of seized drug mixtures using instrumentation other than the DART-AccuTOF provides support for the expanded applicability of this freely available resource. [Display omitted] • ESI- and DART-generated IS-CID spectra are highly comparable. • NIST DIT is compatible with IS-CID spectra from non-DART AccuTOF instrumentation. • Support for expanded applicability of the NIST DART-MS Forensics Database and DIT. • Similar screening results for drug mixtures using ESI- and DART-IS-CID spectra. • Proposed criteria to maximize the value of NIST DIT screening results. [ABSTRACT FROM AUTHOR]

A photoelectron velocity-map imaging (VMI) apparatus has been developed from the DUV-IR photoionization mass spectrometry and spectroscopy instrument. A 45-degree plate-set is designed and combined with the upright reflection time-of-flight mass spectrometer (Re-TOFMS) to pick up target cluster anions and change their trajectory after the vertical reflection. Following the ion-extraction zone, the mass-selected cluster anions then pass through up-down and left-right trajectory adjustment and beam focus until the arrival at the photoelectron detachment zone to encounter the normal incidence of a pulsed UV laser. The detached electrons are subject to acceleration and detected by a dual micro-channel plate detector and imaging on the phosphor screen. This 45-degree ion-extraction photoelectron VMI setup not only expands the function of our DUV-IR instrument for structural chemistry but also facilitates the compatibility with the conventional upright reflection of TOFMS. [Display omitted] [ABSTRACT FROM AUTHOR]

Volcanic gas sampling and post-collection chemical determination in a laboratory may preclude any real-time continuous monitoring of volcanic activity. We describe the development, and show the advantages, of a system used for the continuous monitoring of fumarolic gases discharged from the Pisciarelli site (Campi Flegrei, Southern Italy) based on a commercial quadrupole mass spectrometer (QMS-301 Omnistar™). Although numerous technical problems were addressed due to the ephemeral nature of the emission point and the harsh environment, we also report measurements of the chemical composition of the major gas species emitted from the fumarole for two different periods (in 2009 and 2012). The CO 2 /H 2 S, H 2 S/H 2 , He/CO 2 and CH 4 /CO 2 molar ratios were investigated in order to detect magmatic and/or hydrothermal components in the system, while the N 2 /O 2 ratio was adopted to infer other non-volcanic processes, such as air contamination and mixing with polluted surface waters. The presented methodology allows continuous gas sampling and provides the first evidence of short-term gas variations not available by direct sampling, which is often impractical and hazardous. Compared to the current techniques that are used worldwide for the full characterization of gaseous emissions, i.e. chemical analysis of traditional soda-filled under-vacuum bottles and MultiGAS surveys (laboratory-based and in situ , respectively), QMS-based monitoring is complementary and, in prospect, an alternative. With our method, the geochemical monitoring benefits of the real-time analysis for high sampling rates that can be made comparable to the continuous measurements of geophysical networks. This allows a better understanding of hydrothermal features, particularly of chemical fluctuations occurring on the very short-term, which is fundamental for the evaluation of the evolution of unrest episodes at Campi Flegrei, one of the most hazardous volcanic areas in the world. [ABSTRACT FROM AUTHOR]

A radio frequency ion funnel reaction chamber is applied for use with a proton transfer reaction ion trap mass spectrometer (PIT-MS). The improvement in sensitivity over our dc-only drift tube ranged from 7.2 x for isoprene to 65 x for benzene. The ideal settings of the ion funnel are found to be a dc voltage of 60 V, RF voltage of 240 V and a pressure of 1.80 mbar. An experimental and theoretical investigation of the ion funnel is presented. Simulations using SIMION and experimental measurements of the m / z dependent transmission of the ion funnel are performed, as well as simulations of the trajectories of ions and their survival probability. These are used to deduce a greater understanding of the operation of the ion funnel and the sensitivity improvements. The funnel is shown to favor transmission of higher m/ z, and to increase sensitivity by a combined effect of focusing and increased effective reaction time. The product ions of an example set of compounds are measured systematically and the reagent ion branching profiles studied and compared to ion trap fragmentations. This represents an important undertaking in the characterization studies of ion funnel technology for use in PTR-MS. [ABSTRACT FROM AUTHOR]

A new charge detection mass spectrometer that combines array detection and electrostatic ion trapping to repeatedly measure the masses of single ions is described. This instrument has four detector tubes inside an electrostatic ion trap with conical electrodes (cone trap) to provide multiple measurements of an ion on each pass through the trap resulting in a signal gain over a conventional trap with a single detection tube. Simulations of a cone trap and a dual ion mirror trap design indicate that more passes through the trap per unit time are possible with the latter. However, the cone trap has the advantages that ions entering up to 2 mm off the central axis of the trap are still trapped, the trapping time is less sensitive to the background pressure, and only a narrow range of energies are trapped so it can be used for energy selection. The capability of this instrument to obtain information about the molecular weight distributions of heterogeneous high molecular weight samples is demonstrated with 8 MDa polyethylene glycol (PEG) and 50 and 100 nm amine modified polystyrene nanoparticle samples. The measured mass distribution of the PEG sample is centered at 8 MDa. The size distribution obtained from mass measurements of the 100 nm nanoparticle sample is similar to the size distribution obtained from transmission electron microscopy (TEM) images, but most of the smaller nanoparticles observed in TEM images of the 50 nm nanoparticles do not reach a sufficiently high charge to trigger the trap on a single pass and be detected by the mass spectrometer. With the maximum trapping time set to 100 ms, the charge uncertainty is as low as ±2 charges and the mass uncertainty is approximately 2% for PEG and polystyrene ions. [ABSTRACT FROM AUTHOR]

In this study we report theoretical and experimental evidence for the formation of ionic products by the ion-neutral reaction of C 2 H 2 N + with C 2 H 6 . Our investigations consist of laboratory measurements using a guided ion beam mass spectrometer together with complementary ab initio quantum chemical computations, at the MP2/6-311++G(d,p) level of theory, in order to elucidate the energetics and geometries of the intermediates and transition states that are involved in the production of the observed product ions. This study also provides insights on the isomeric nature of the observed product ions, their formation pathways together with collision energy and pressure dependences. The experimental data agrees well with the predictions of the ab initio calculations. Despite data provides evidence for the occurrence of C 2 H 5 + as the most salient product ion, the production of CH 3 + , C 2 H 3 + , C 3 H 5 + , C 3 H 7 + and C 2 H 4 N + is also evident. A reaction scheme was proposed to elucidate the mechanisms responsible for the formation of the observed product ions. These processes might be intermediate steps in the generation of long chain carbon and nitrogen-bearing compounds in Titan's ionosphere, the interstellar medium or circumstellar envelopes. [ABSTRACT FROM AUTHOR]

We describe CHILI, the Chicago Instrument for Laser Ionization, a new resonance ionization mass spectrometer developed for isotopic analysis at high spatial resolution and high sensitivity of small samples like contemporary interstellar dust grains returned by the Stardust spacecraft. We explain how CHILI addresses the technical challenges associated with such analyses by pushing most technical specifications towards their physical limits. As an initial demonstration, after many years of designing and developing CHILI, we have analyzed presolar silicon carbide grains for their isotopic compositions of strontium, zirconium, and barium. Subsequently, after further technical improvements, we have used CHILI to analyze, for the first time without interference, all stable isotopes of iron and nickel simultaneously in presolar silicon carbide grains. With a special timing scheme for the ionization lasers, we separated iron and nickel isotopes in the time-of-flight spectrum such that the isobaric interference between 58 Fe and 58 Ni was resolved. In-depth discussion of the astrophysical implications of the presolar grain results is deferred to dedicated later publications. Here we focus on the technical aspects of CHILI, its status quo, and further developments necessary to achieve CHILI’s ultimate goals, ∼10 nm lateral resolution and 30–40% useful yield. [ABSTRACT FROM AUTHOR]

Micron-scale (∼10 μm) analyses of rare earth elements (REEs) in silicate glass, zircon and apatite were carried with nano-scale secondary ion mass spectrometer (NanoSIMS) operating at high mass resolution mode (m/Δm = ∼10000, 10%), which eliminating isobaric interferences of heavy REEs by light REE monoxides. To achieve high lateral resolution, the primary O − probe was optimized to a current of ∼1 nA and a diameter <2.5 μm, scanning over the analysis area of 5 × 5 μm 2 or 10 × 10 μm 2 . The analyses were conducted at a combined mode of multi-collection and peak-jumping to improve the analytical efficiency. Fifteen ion species including rare earth elements and a reference element (Si or Ca) were counted through 4 times of magnetic field switch. The standards of NIST glass, apatite and zircon were analyzed in this study, which represent flat patterns, LREE-enriched and LREE-depleted and show different matrix effects. The relative sensitivity factors (RSF) of REEs are higher in zircon than NIST glass by a factor of 20–50% referred to 30 Si + , and they are higher in apatite than NIST glass by a factor of 2–3 referred to 42 Ca + . Therefore, the absolute concentration of REEs could be only calibrated with the matrix-matched mineral standards in the SIMS analysis. The analytical reproducibilities (1SD) were <5% for silicate glass (NIST SRM 610), <10% for apatite (Durango) and <15% for zircon (M257). The analytical accuracies determined from the measurements of the standards NIST glass (NIST SRM 612), apatite (MAD and Otter lake) and zircon (91500) were better than 10%, 20% and 30%, respectively, except for La interfered by ZrSiO and ZrO 3 for zircon. [ABSTRACT FROM AUTHOR]

Since their introduction, digital quadrupole mass spectrometers have described by analogy to traditional sinusoidal devices. However, digital quadrupoles exhibit unique behaviors and simplify many complex ion handling operations due to their uniquely flexible control over the frequency, duty cycle and amplitude of applied potentials. Matrix solutions to the Hill differential equation are used to explore the effects of these additional degrees of freedom on ion stability. Two parameters are explored: varying the frequency ratio of the applied potentials introduces a predictable number of bands of instability to the stability diagram. Varying the amplitude ratio of the applied potentials tunes the width of those unstable bands. Stability diagrams governing a digital mass filter employing asymmetric driving potentials to generate an arbitrary number of pass bands of adjustable width are systematically described. [ABSTRACT FROM AUTHOR]

Electron impact ionisation and dissociative ionisation of the two smallest primary alcohols have been investigated. A quadrupole mass spectrometer was used, with an internal ionising electron source resulting in an energy resolution of ∼0.8 eV. The partial ionisation cross sections (PICS) for a number of individual cations have been measured for energies between 10–100 eV. The present data compares well with previous results for methanol. Surprisingly, however, this study is the first to report individual PICS for ethanol. The sum of the present PICS for both methanol and ethanol is also compared to the total ionisation cross sections reported in the literature and are found to be in good accord. Additionally, appearance energies have been derived by fitting the Wannier equation to data measured within ∼2 eV of the cation formation threshold. However, the low energy resolution limits the precision with which these values are able to be determined. This study also establishes the validity of the data collected using the apparatus at Universidade Federal de Juiz de Fora (UFJF) and so provides a solid foundation for further studies of larger alcohols. [ABSTRACT FROM AUTHOR]

The rapid chemical identifications are critical when treating poisoning patients in hospitals. Conventional liquid chromatography-MS techniques would consume hours of valuable rescue time, even without considering sample transfer time. A diagnostic device readily available in emergency room would help doctors make quick treatment plan and greatly save rescue time. Over the past two decades, several key technologies have been developed for mass spectrometer miniaturization. As a first attempt, three complementary technologies (discontinuous atmospheric pressure interface, sinusoidal frequency scanning ion trap driving and Faraday detection) were integrated together, which enables the construction of a handheld mass spectrometer. The whole device weights 5.2 kg and could work for 2 h on battery. It has dimensions of 21 by 21.6 by 12.3 cm, which is able to be held by one hand. Different types of ionization sources could be coupled with the mass spectrometer to facilitate different sample analysis. This MS device has mass resolution: up to 900; limit of detection: 0.1 μg/mL. With acceptable analytical performances, this device could potentially be used in field or conventional hospitals for emergency management of poisonings. The capability of detecting drug of abuse and warfare agents/simulants were demonstrated. [Display omitted] • As a first attempt, three complementary technologies were integrated together, which enables the construction of a handheld mass spectrometer. • The capability of coupling with various ionization sources for drug of abuse and warfare agent analyses was demonstrated. • The device weights ∼5.2 kg, works for ∼2 h, which could be applied in emergency rooms or field hospitals. [ABSTRACT FROM AUTHOR]

Effectively focusing and transmitting ions from near atmospheric region ion sources to high vacuum mass analyzers is a key factor that affects the sensitivity and dynamic range in mass spectrometry. To improve the efficiency of ion transmission under limit vacuum conditions, a novel electrodynamic ion transmission device (MIR F-Disc) was developed and characterized in this work. An ion funnel was divided into four equal columns, all of which formed one pole in quadrupole field in the axial direction, thereby forming a coupling between the quadrupole field and the ion funnel electric field. The MIR F-Disc concept was verified by simulations, the optimal transmission efficiency was 70%–80%. Additionally, the MIR F-Disc was used as an atmospheric pressure ionization introduction orifice for a lab-built time-of-flight mass spectrometer. Three different modes of radio frequency (RF) and direct current (DC) electrical field applications were tested. The transmission efficiencies for peptides and proteins were typically over 70% of the total incoming currents from capillary, which was consistent with the simulation results. MIR F-Disc could provide ion fragmentation function under certain operating conditions with efficiency of over 80%. Taken together, the smaller size (less than 3 cm length with 0.7 mm orifice) and significant ion transmission efficiency as well as the ion fragmentation ability make the MIR F-Disc more suitable for mini-mass spectrometry. [Display omitted] • High ion transmission efficiency, simulation results show that the MIR F-Disc has an ion transmission efficiency of up to approximately 80% and actual tests based on reserpine give over 70% efficiency. • Wide mass range, the MIR F-Disc provides three different operation modes. Quadrupole mode provide sufficient transmission for ions with relatively small mass, which makes up for the shortcomings of traditional ion funnel. MIR F-Disc also provide Funnel mode used for large ions. The mixed mode is a combination of Funnel and Quadrupole mode which provides largest mass range ion transmission. • Ability of ion fragmentation, the quadrupole field with controlled vacuum allows the MIR F-Disc to fragment incoming ions, thus providing the possibility of tandem mass spectrometry. • Compact size, the overall length of the MIR F-Disc is less than 3 cm which makes it suitable for a variety of scenarios. The small outlet orifice reduces the requirement for vacuum system which makes it especially suitable for the miniaturization of mass spectrometry. [ABSTRACT FROM AUTHOR]

The volatile element Cl can be lost during the formation and evolution of planetary bodies, leading to fractionation of its two stable isotopes 35Cl and 37Cl. Chlorine isotope variations (reported as δ37Cl in parts per thousand (‰) relative to Standard Mean Ocean Chloride, SMOC) are documented to exceed 80‰ between different lunar rock samples and have been variably interpreted as the fingerprint of degassing during accretion, magma ocean, or volcanic portions of lunar history. The large intersample and intrasample variations observed by both bulk isotope ratio mass spectrometry (IRMS) and in-situ secondary ion mass spectrometry (SIMS) methods are difficult to interpret in part because of a paucity of bulk Cl isotope measurements. This lack of high-precision bulk data is due to the relative rarity of IRMS laboratories capable of making these high precision measurements on small samples of precious planetary materials such as those returned by human or robotic exploration. Here we present a new method for performing high precision δ37Cl measurements using the modified Middleton ion source of an existing accelerator mass spectrometer. For samples with as little as 1 μg Cl–the equivalent of 2–4 mm3 of a typical lunar rock sample–the average cathode accuracy is ∼1‰. Cathode reproducibility is typically ∼1‰ (2σ) for samples with at least 10 μg of Cl, increasing to ∼3–6‰ for aliquots with ∼1–2 μg Cl, similar to published SIMS results and sufficient to study astromaterials from the Moon, Mars, or 4 Vesta, which have tens of ‰ observed variations. [Display omitted] • δ37Cl measurements made using the ion source of an accelerator mass spectrometer. • For samples with ≥1 μg Cl, 69% of measurements are accurate to ≤1‰, and 86% to ≤2‰. • Reproducibility is ∼1‰ for samples with ≥10 μg Cl, and ∼3–6‰ for ∼1–2 μg Cl. • Method is sufficient to study astromaterials from the Moon, Mars, or 4 Vesta. [ABSTRACT FROM AUTHOR]

Accurate quantification of the composition in small amounts of gas is a challenging task, since there are a limited number of analytical methods having a highly sensitive and fast response. A recently introduced ion trap mass spectrometer (ITMS) was preliminarily studied as a candidate for routine quantitative analysis of small gas amounts detected as gas bursts. The ITMS was calibrated by an innovative in situ procedure using three pure gases: nitrogen, argon and hydrogen. Total pressure versus flow rate dependence was determined over three orders of magnitude, while the gas fraction pattern was simultaneously recorded by the ITMS. The obtained specific gas sensitivities of the ion gauge and pertaining ITMS fraction patterns were applied for quantification of synthetic binary gas mixtures with a composition ratio equal to 1:1, ranging from 3.17 × 10 −3 mbar L to 6.7 × 10 −5 mbar L. The error in quantification was substantially higher than for pure gases and depended on the amount and gas type. Argon was noticeably overestimated, while hydrogen was highly underestimated. At smallest gas amounts, the disproportion was as high as 1:0.36. The origin of error for low mass ions seems to be related to the ITMS's intrinsic principle of ion generation, separation and detection. [ABSTRACT FROM AUTHOR]

We describe a unique and novel isotope ratio mass spectrometer (IRMS), the Panorama , developed explicitly for high-mass-resolution analysis of isotopologue ratios of gas samples. The double-focussing instrument routinely operates at a mass resolving power of 40,000 with a maximum useful MRP of ∼80,000. The instrument achieves this exceptional MRP for a multi-collector using a Matsuda ion optical design with an ESA radius of 1018 mm and a magnetic sector radius of 800 mm. Collectors comprise 9 Faraday cups and a single channel of ion counting each with continuously variable collector slits. First results demonstrate both accuracy and precision comparable to, and in some cases, surpassing, other gas-source multi-collector IRMS instruments for singly-substituted species. For example, accurate bulk D/H and 13 C/ 12 C for methane gas measured with CH 4 as the analyte are measured simultaneously with internal precision of 0.02–0.04‰ (1 std error) and ∼0.006‰ (1 se), respectively. Ion counting with continuous rebalancing of sample and standard gases permits high-precision measurements of rare, multiply-substituted isotopologues with relative abundances as small as ∼0.1 ppm. In the case of methane, both 13 CH 3 D/ 12 CH 4 and 12 CH 2 D 2 / 12 CH 4 ratios are measured with precision of ∼0.1‰ and ∼0.5‰, respectively. Accuracy of the multiply-substituted species measurements is demonstrated using isotope ratio mixing experiments. The ability to measure both Δ 13 CH 3 D and ΔCH 2 D 2 (‰ variations relative to the stochastic reference frame) provides heretofore unmatched capabilities to identify kinetic reaction pathways, isotope fractionation during transport, mixing, as well as temperatures of formation for methane gas. The high-resolution instrument can be used for a wide variety of applications. For example, it easily resolves 36 Ar + from 18 O 18 O + for oxygen bond-ordering studies. It also easily resolves 14 N 16 O+ from 15 N 15 N+ for measurements of the doubly-substituted N 2 species. [ABSTRACT FROM AUTHOR]