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A discharge-type fusion neutron source generates neutrons by fusion reactions of hydrogen isotope atoms. In order to operate the fusion device based on the deuterium–tritium (D–T) fusion reaction, the tritium inventory is required to be decreased. In the present work, a self-sufficient system was installed into the fusion device for reducing the amount of hydrogen isotope fuel gas. The fuel gas was supplied and recovered with an intermetallic compound ZrCo in a sealed chamber in this system. A deuterium–deuterium operation was maintained for more than 60 min with stable discharge voltages, and the temperature of the ZrCo bed was changed to improve the neutron production rate. Factors that influenced the pressure inside the chamber were determined and optimized. Gas analysis using a quadrupole mass spectrometer indicates a dilution of the deuterium fuel was caused by hydrogen isotope exchange between the supplied deuterium gas and the absorbed protium on the chamber and electrodes surface. This system's hydrogen isotope control method and the amount of fuel were proposed for a D–T operation.

To support a phase III randomized trial of the multi-targeted tyrosine kinase inhibitor cabozantinib in neuroendocrine tumors, we developed a high-performance liquid chromatography mass spectrometry method to quantitate cabozantinib in 50 μL of human plasma. After acetonitrile protein precipitation, chromatographic separation was achieved with a Phenomenex synergy polar reverse phase (4 μm, 2 × 50 mm) column and a gradient of 0.1% formic acid in acetonitrile and 0.1% formic acid in water over a 5-min run time. Detection was performed on a Quattromicro quadrupole mass spectrometer with electrospray, positive-mode ionization. The assay was linear over the concentration range 50–5000 ng/mL and proved to be accurate (103.4–105.4%) and precise (

Novel, accurate, selective, and rapid high-performance liquid chromatography mass spectrometry method was developed for simultaneous analysis of amoxicillin trihydrate, dicloxacillin sodium, and their official impurity 6-aminopenicillanic acid. The chromatographic separation was carried out by applying the mixture on a C18 column (3.5 µm ps, 100 mm × 4.6 mm id) using acetonitrile:water (65 : 35 by volume) as a mobile phase within only 4 min. The quantitative analysis was executed using single quadrupole mass spectrometer in which electrospray ionization, selected ion monitoring, and negative mode were operated. The retention times were 1.61, 2.54, and 3.50 mins for amoxicillin, 6-aminopenicillanic acid, and dicloxacillin, respectively. The method was validated in linear ranges of 2–28 µg mL−1, 2–35 µg mL−1, and 1–10 µg mL−1 for amoxicillin, dicloxacillin, and 6-aminopenicillanic acid, respectively. The results obtained from the suggested HPLC/MS were statistically compared with those obtained from the reported HPLC method, where no significant difference appeared respecting accuracy and precision. According to the analytical eco-scale assessment method, the proposed method was proved to be greener than the reported one, where the analysis time and the amount of the wasted effluent decreased.

We show how the powerful combination of temperature-dependent kinetics coupled with detailed statistical modeling can be used to derive dynamical information about transition state barrier heights, the importance of multiple entrance channel complexes, crossings between spin surfaces, energetics, product states, and other information for metal-ion reactions. The methods are not new, but with improved computers, ion sources, ion transport, and better detection techniques, the ability to derive such parameters from the combination of methods has improved greatly. Temperature-dependent kinetics is very sensitive to the above list of parameters because the energy is varied in a controlled way that can be easily modeled. The present measurements, performed in our variable-ion source temperature-adjustable selected-ion flow tube (VISTA-SIFT), have been enabled by advances in ion transport and injection improvements so that dim sources can be used. Replacing the quadrupole mass spectrometer detector with a time-of-flight mass spectrometer solved additional problems. Quantum chemical calculations have improved greatly and provide details about the surfaces, as well as frequencies, to use as starting points for the statistical modeling. For ion-molecule reactions, incorporation of both energy and angular momentum effects are important and we have developed an in-house computer program, based on the work of Juergen Troe, to rapidly compare statistical modeling predictions to the experimental data. As we show, modeling the kinetics data can often determine the most important parameters controlling the reactivity and deriving them is much simpler and usually more accurate than detailed ab initio calculations or dynamical modeling. Additionally, we show that even without statistical modeling, temperature-dependent rate constants as a function of metal anion cluster size can be used to show that such species react by the same mechanism as surfaces. In this review, we discuss reactions of metallic atomic ions, small metal oxide ions, mixed metal oxide ions, and a series of metallic anionic cluster reactions with small molecules such as CO, O2, CO2, N2O, CH4, and several other species. Particular attention was paid to reactions involving bond activation pertinent to catalysis.

Nitrosamine impurities in angiotensin II receptor antagonists (sartans) containing a tetrazole group represent an urgent concern for active pharmaceutical ingredient (API) manufacturers and global regulators. Regarding safety, API manufacturers must develop methods to monitor the levels of each nitrosamine impurity before individual batch release. In this study, we developed and validated a sensitive, selective, and high-throughput method based on headspace gas chromatography–mass spectrometry (HS-GC–MS) for the simultaneous determination of four nitrosamines in losartan potassium API with simple sample preparation. N-Nitrosodimethylamine (NDMA, m/z 74), N-nitrosodiethylamine (NDEA, m/z 102), N-nitrosoethylisopropylamine (EIPNA, m/z 116), and N-nitrosodiisopropylamine (DIPNA, m/z 130) levels were quantified using an electron impact, single quadrupole mass spectrometer under a selected-ion-monitoring acquisition method. The method was validated according to the Q2(R1) ICH guidelines. The calibration curves of the assay ranged from 25 to 5000 ng/mL with limits of quantitation of 25 ppb for NDMA and NDEA and 50 ppb for DIPNA and EIPNA. The accuracy of the developed method ranged from −7.04% to 7.25%, and the precision %CV was ≤11.5. Other validation parameters, including specificity, stability, carryover, and robustness, met the validation criteria. In conclusion, the developed method was successfully applied for the determination of nitrosamines in losartan potassium APIs.

Tandem mass spectral (MS/MS) data in liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis are often contaminated as the selection of precursor ions is based on a low-resolution quadrupole mass filter. In this work, we developed a strategy to differentiate contamination fragment ions (CFIs) from true fragment ions (TFIs) in an MS/MS spectrum. The rationale is that TFIs should coelute with their parent ions, but CFIs should not. To assess coelution, we performed a parallel LC-MS/MS analysis in data-independent acquisition (DIA) with all-ion-fragmentation (AIF) mode. Using the DIA (AIF) data, peak-peak correlation (PPC) score is calculated between the extracted ion chromatogram (EIC) of the fragment ion using the MS/MS scans and the EIC of the precursor ion using the MS1 scans. A high PPC score is an indication of TFIs, and a low PPC score is an indication of CFIs. Tested using metabolomics data generated by high resolution QTOF and Orbitrap MS from various vendors in different LC-MS configurations, we found that more than 70% of the fragment ions have PPC scores < 0.8 and identified three common sources of CFIs, including (1) solvent contamination, (2) adjacent chemical contamination, and (3) undetermined signals from artifacts and noise. Combining PPC scores with other precursor and fragment ion information, we further developed a machine learning model that can robustly and conservatively predict CFIs. Incorporating the machine learning model, we created an R program, MS2Purifier, to automatically recognize CFIs and clean MS/MS spectra of metabolic features in LC-MS/MS data with high sensitivity and specificity.

Steam gasification kinetics studies were conducted in a modified drop tube fixed bed reactor to approximate the injection of ambient temperature coal into a fluidized bed gasifier. Product gases were measured using a customized rapid response gas analysis system with a quadrupole mass spectrometer. Experiments were done within Regime I temperature range (no mass transfer restrictions), and effects of temperature and pressure on surface chemical reaction were analyzed using three different particle size ranges. The random pore model closely fits the experimental results and the fitting parameters are listed. Char characterizations are presented, including surface area measurements and scanning electron microscope images. Mass transfer resistances were analyzed by comparing experimental and theoretically predicted effectiveness factors using the Thiele modulus, based on particle sizes, temperature, total pressure, and steam partial pressure.

The dynamic behavior of Pd species and the CeO2 support of 1 wt% Pd/Al2O3 and Pd/CeO2 catalysts during three-way catalysis was examined in real time with operando multi-probe analysis using a micro gas chromatograph, a NOx meter, and a quadrupole mass spectrometer and time-resolved quick X-ray absorption spectroscopy (XAS) measurements. With additional ex situ NO pulse measurement, the results demonstrated the effect of oxygen storage materials under ideal automobile exhaust conditions, which can be summarized into a well-known anchoring effect of CeO2 on active metal species, an oxygen storage/release effect to maintain near stoichiometric conditions on the catalyst surface, NO reduction ability of CeO2 itself, and storage/release of carbonaceous species on/from CeO2.

Gd-based contrast agents (GBCAs) are frequently administered to patients for magnetic resonance imaging to enhance tissue contrasts. After examination, they are excreted and enter surface waters via local wastewater treatment plants' effluents where they lead to anthropogenic Gd anomalies in the environment of metropolitan areas with developed healthcare. This work presents the speciation analysis of GBCAs in water samples from Australia by targeting individual GBCAs in effluent, river and seawater samples obtained from New South Wales (Sydney area), the Northern Territory (Alice Springs) and Victoria (Melbourne area). A method based on hydrophilic interaction liquid chromatography (HILIC) coupled to inductively coupled plasma-mass spectrometry (ICP-MS) provided rapid separation and quantification of four common GBCAs in under three minutes. To improve the sensitivity, ion extraction and transport processes were optimised and the quadrupole mass filter was operated with an increased mass bandpass, decreasing limits of detection to between 18 and 24 ng L−1 for individual GBCAs. This allowed detection of Gd-DOTA, Gd-BT-DO3A and Gd-DTPA-BMA at concentrations of up to 160 ng L−1 in water samples collected from rivers within the proximity of effluents of local wastewater treatment plants. The analysis of GBCAs in oceanic sea water required the development of a novel automated micro-solid phase extraction (μSPE) method for matrix elimination and analyte pre-concentration enabling the detection of Gd-DOTA and Gd-BT-DO3A.

International audience; Nitromethane has many applications, such as in racing, as a gasoline fuel additive, and as a monopropellant. Despite a large number of studies and the small size of the molecule, the combustion chemistry of nitromethane is still not well understood. To improve models, the pyrolysis of nitromethane (CH3NO2) was investigated experimentally in shock tubes and in a micro flow reactor with a controlled temperature profile (MFR), under dilute conditions. Several spectroscopic diagnostics were used in the shock tubes to follow the concentration time histories of CO, H2O (both using IR laser absorption), and CH3NO2 (UV light absorption). A quadrupole mass spectrometer was used to measure CH3NO2, NO2, CH4, C2H4, and C2H2 at various temperatures with the MFR. These unique experimental results were compared to modern, detailed kinetics models from the literature, and no mechanism was able to reproduce these data over the wide range of conditions investigated. Predictions for the CO and H2O levels were generally inaccurate, and the CH4, C2H4, and C2H2 predictions were poor in most cases for the MFR data. Importantly, all models largely differ in their predictions. A numerical analysis was performed to identify ways to improve the next generation of nitromethane models. Results indicate that nitromethane decomposition needs to be improved below 1050 K, and that hydrocarbon-NOx interactions still need to be further investigated.

Analyses of the composition of exhaled gases are among important areas of non-invasive medicine. Diagnostics based on the analysis of exhaled gases offers several advantages over traditional laboratory methods. An analysis of a gas mixture is safe for the staff, because it does not involve chemical and biological fluids. The analysis is relatively inexpensive, takes little time, and ensures the detection of volatile components in the exhaled gas at the trace level of substances in real time. This paper discusses algorithms for the processing of mass spectra of exhaled gases obtained on an MC7-200 quadrupole mass spectrometer with electron ionization and the direct capillary injection of a sample. A comparative evaluation of algorithms for the detection of spectral lines in mass spectra based on data convolution with a model of response function or its derivatives is given. The Hermite function, the Gaussian function, and its even-order derivatives are considered as convolution kernels. The results of evaluation of the potential for increasing the signal-to-noise ratio by algorithms of convolution with these functions are presented.

Oxide dispersion-strengthened materials W-1wt%Pr2O3 and W-1wt%La2O3 were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 1021 ions/m2 under 600 °C using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr2O3 and W-1wt%La2O3. At 1.0 × 1020 He+/m2, the average loops size of the W-1wt%Pr2O3 was 4.3 nm, much lower than W-1wt%La2O3 of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 1021 He+/m2 on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He+ pre-irradiation, deuterium (D) retention of doped W materials increased after He+ irradiation, whose retention was unsaturated at the damage level of 1.0 × 1022D2+/m2. The present results implied that irradiation effect of He+ ions must be taken into account to evaluate the deuterium retention in fusion material applications.

The method is proposed for express diagnostics of diseases according to the data of mass spectrometric analysis of exhaled air. An algorithm for calculating the probability of diseases has been developed and tested. The results of data processing of patients treated in two oncological clinics are presented. The calculation of the probability of disease according to the data of mass spectrometric analysis of exhaled air is based on attributing the mass spectrum of the tested patient to the mass-spectra of the corresponding control group. Each control group is formed by collecting an array of spectra from at least ten patients with the same disease. Diagnostics is performed by transforming the matrix of spectra of the control group and the spectrum of a patient being tested into the space of the principal components. The probability of a disease is determined by the Euclidean distance of the patient's coordinates from the centroid of the control group in the multidimensional space of these principal components.

Individuals are exposed to a wide variety of chemicals over their lifetime, yet current understanding of mixture toxicology is still limited. We present a two-step analytical method using a gas chromatograph-triple quadrupole mass spectrometer that requires less than 1 mL of sample. The method is applied to 183 plasma samples from a study population of children with autism spectrum disorder, their parents, and unrelated neurotypical children. We selected 156 environmental chemical compounds and ruled out chemicals with detection rates less than 20% of our study cohort (n = 61), as well as ones not amenable to the selected extraction and analytical methods (n = 34). The targeted method then focused on remaining chemicals (n = 61) plus 8 additional polychlorinated biphenyls (PCBs). Persistent pollutants, such as p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE) and PCB congeners 118 and 180, were detected at high frequencies and several previously unreported chemicals, including 2,4,6-trichlorophenol, isosafrole, and hexachlorobutadiene, were frequently detected in our study cohort. This work highlights the benefits of employing a multi-step analytical method in exposure studies and demonstrates the efficacy of such methods for reporting novel information on previously unstudied pollutant exposures.

Background Acetyl octapeptide-3 (SNAP-8) is an antiaging peptide that is more effective than acetyl hexapeptide-3, which is more stable than botulinum toxin and effectively relieves facial wrinkles. Products containing SNAP-8 such as patch are producing, but analytical method has not been reported to determination of SNAP-8. Method Mobile phase, collision energy, and desolvation line temperature were optimized, and mass spectral data set for SNAP-8 was newly constructed by liquid chromatography-triple quadrupole mass spectrometer in multiple reaction monitoring mode. Results The developed method showed good linearity (r ≥ 0.9971) with limit of quantification of 0.0125 ng/mL, repeatability (% relative standard deviation = 0.02 to 0.12) and accuracy (% relative error = − 1.68 to 1.44) under optimal conditions. This method was successfully applied to a biodegradable microneedle patch loaded with SNAP-8. Conclusion The present method for the quantification of SNAP-8 may be useful for quality control in the cosmetic fields.

After its introduction in the early 1990s, comprehensive two-dimensional gas chromatography (GC×GC) has evolved from a separation science research tool to the central component of many industries. Despite the maturity of the technique, some fields remain reluctant to its use in routine applications. In the case of forensic science, some constraints are the strict requirements enforced in forensic laboratories and the time and effort that must be invested for intralaboratory method validation. Concerns may also arise about whether information could be lost when transitioning to a new technique. This study reports on a method translation from conventional one-dimensional (1D) GC to GC×GC, ensuring the integrity of data as conversion is made. The GC was retrofitted with a reverse fill/flush (RFF) flow modulator and equipped with dual-channel detection using a quadrupole mass spectrometer (qMS) and a flame ionization detector (FID). The parallel use of two detectors, where qMS was applied for qualitative identification and FID for quantification, allowed higher flows and slightly wider peaks to be exploited for the analysis of a volatile organic compound (VOC) reference mixture relevant to forensic VOC profiling. Peak quality assessment and calibration curves using GC-qMS and GC×GC-qMS/FID document the transfer and adaptation of the original method without a loss in data quality. Furthermore, the preprocessing and the data analysis processing steps, including calibration and peak quality assessment for each of the three data sets, are explained in detail. This information provides benchmark data for routine laboratories that want to implement a GC×GC approach into routine workflows.

A pulsed laser photolysis-photoionization mass spectrometer system has been employed to measure the rate constants of HCCO + O2 and HCCCO + O2 over the temperature range 243-423 K in 1.2-8.4 Torr of He or N2. Radicals of HCCO and HCCCO were produced by 193 nm ArF laser photolysis of ethyl ethynyl ether and methyl propiolate, respectively. HCCO was photoionized by a Kr resonance lamp with a CaF2 window (10.03 eV), and HCCCO was ionized by a Xe lamp with a sapphire window (8.44 eV). Both ions were detected as parent ions in a quadrupole mass spectrometer. From analysis of the time profiles of the ion signals for various O2 concentrations, the overall rate constants at 298 K are represented by the values k2 = (6.3 ± 1.0) × 10-13 for HCCO + O2 and k5 = (5.7 ± 0.6) × 10-12 for HCCCO + O2 in the units cm3 molecule-1 s-1. The rate coefficients for the two reactions can be described by k2(T) = (1.5-0.7+1.5) × 10-12 exp[-(225 ± 220)/T] and k5(T) = (1.8-0.9+1.9) × 10-12 exp[(343 ± 228)/T] in the units cm3 molecule-1 s-1 over the temperature range 243-423 K.

Operation with positive ions formed from the impact of high energy electrons (usually 70 eV, which exceeds the ionization energy of the molecules) is a standard mode for mass spectrometric detectors of most gas chromatography-mass spectrometric complexes (GC/MS) in the basic configuration. At the same time, we have shown that the option of setting the energy of ionizing electrons (maintained in the design of some serial devices) within the pre-ionization region also allows one to obtain mass spectra of negative ions (NI) which, in turn, significantly expands the analytical potential of standard equipment. The formation of NI occurs in the low-energy range of 0 – 15 eV due to resonant capture of electrons by molecules (REC). In contrast to positive ions, the intensity of NI formation sharply (resonantly) depends on the electron energy and this dependence is characteristic of each chemical compound. Both the relative intensity of the mass-peaks and, in general, the ionic composition of the formed mass spectrum of NI significantly depend on the electron energy. The problem of choosing the optimal energy of ionizing electrons providing the same efficiency of mass-spectrometric determination of all components of complex mixtures of dissimilar compounds is also associated with the features of negative ion formation during chromatography-mass spectrometric analysis. To address the problem, we propose a technique providing generation of complete (in NI composition and intensities) mass spectra of NI through repeated variation of the energy of ionizing electrons in a given range of 0 – 10 eV. Technical implementation of the technique [1] was carried out at the Design Bureau «Chromatec «(Yoshkar Ola, Russia) in the form of a special electronic device, which was tested in pilot operation as part of the gas chromatograph complex with a quadrupole mass spectrometer «Chromatec». We describe the principle of operation of the device and present the results of tests.

Understanding how catalysts work during chemical reactions is crucial when developing efficient catalytic materials. The dynamic processes involved are extremely sensitive to changes in pressure, gas environment and temperature. Hence, there is a need for spatially resolved operando techniques to investigate catalysts under working conditions and over time. The use of dedicated operando techniques with added detection of catalytic conversion presents a unique opportunity to study the mechanisms underlying the catalytic reactions systematically. Herein, we report on the detailed setup and technical capabilities of a modular, homebuilt gas feed system directly coupled to a quadrupole mass spectrometer, which allows for operando transmission electron microscopy (TEM) studies of heterogeneous catalysts. The setup is compatible with conventional, commercially available gas cell TEM holders, making it widely accessible and reproducible by the community. In addition, the operando functionality of the setup was tested using CO oxidation over Pt nanoparticles.

Utilizing a magnetron-sputtering (MagS) source in tandem with a multiple-ion laminar flow tube (MIFT) reactor and a customized triple quadrupole mass spectrometer (TQMS), we have prepared clean Pbn...

Disinfection byproducts (DBPs) are a ubiquitous source of chemical exposure in drinking water and have been associated with serious health impacts in human epidemiologic studies. While toxicology studies have pinpointed DBPs with the greatest toxic potency, analytical methods have been lacking for quantifying complete classes of most toxic DBPs at sufficiently low quantification limits (ng/L). This new method reports the parts-per-trillion quantification for 61 toxicologically significant DBPs from 7 different chemical classes, including unregulated iodinated haloacetic acids (HAAs) and trihalomethanes (THMs), haloacetaldehydes, haloketones, haloacetonitriles, halonitromethanes, and haloacetamides, in addition to regulated HAAs and THMs. The final optimized method uses salt-assisted liquid-liquid extraction in a single extraction method for a wide range of DBPs, producing the lowest method detection limits to-date for many compounds, including highly toxic iodinated, brominated, and nitrogen-containing DBPs. Extracts were divided for the analysis of the HAAs (including iodinated HAAs) by diazomethane derivatization and analysis using a GC-triple quadrupole mass spectrometer with multiple reaction monitoring, resulting in higher signal-to-noise ratios, greater selectivity, and improved detection of these compounds. The remaining DBPs were analyzed using a GC-single quadrupole mass spectrometer with selected ion monitoring, utilizing a multimode inlet allowed for lower injection temperatures to allow the analysis of thermally labile DBPs. Finally, the use of a specialty-phase GC column (Restek Rtx-200) significantly improved peak shapes, which improved separations and lowered detection limits. Method detection limits for most DBPs were between 15 and 100 ng/L, and relative standard deviations in tap water samples were mostly between 0.2 and 30%. DBP concentrations in real samples ranged from 40 to 17 760 ng/L for this study.

We developed a robust analytical method for quantification of malondialdehyde (MDA) in urine and serum samples using dansylhydrazine (DH) as a derivatizing reagent. The derivatization procedure was partially carried out using an autosampler injection program to minimize errors associated with the low-volume addition of reagents and was optimized to yield a stable hydrazone derivative of MDA and its labeled d2-MDA analogue. The target MDA-DH derivatives were separated on an Agilent Zorbax Eclipse Plus Phenyl-Hexyl (3.0 × 100 mm, 3.5 μm) column. The mass-to-charge ratios of the target derivatives [(M+H)+ of 302 and 304 for MDA-DH and d2-MDA-DH, respectively] were analyzed in single ion monitoring mode using a single quadrupole mass spectrometer operated under positive electrospray ionization. The method limits of quantification were 5.63 nM (or 0.405 ng/mL) for urine analysis and 5.68 nM (or 0.409 ng/mL) for serum analysis. The quantification range for urine analysis was 5.63–500 nM (0.405–36.0 ng/mL) while the quantification range for serum analysis was 5.68–341 nM (0.409–24.6 ng/mL). The method showed good relative recoveries (98–103%), good accuracies (92–98%), and acceptable precisions (relative standard deviations 1.8–7.3% for inter-day precision; 1.8–6.1% for intra-day precision) as observed from the repeat analysis of quality control samples prepared at different concentrations. The method was used to measure MDA in individual urine samples (n = 287) and de-identified archived serum samples (n = 22) to assess the overall performance of the method. The results demonstrated that our method is capable of measuring urinary and serum levels of MDA, allowing its future application in epidemiologic investigations.

Mass spectrometry (MS) has been widely used in the detection of volatile organic compounds (VOCs). Sensitivity can be improved by coupling with appropriate pretreatment technology, such as selective adsorption and desorption of analytes using specific sorbent materials. This paper introduces a modified desorption strategy, which integrates cryotrapping adsorption, vacuum desorption, and thermal desorption. Characterization of the proposed pretreatment method has been carried out on a miniature quadrupole mass spectrometer equipped with an electron impact ionization source. During experiments, VOC samples were first collected by using a Tenax sorbent tube cooled in a drikold cryotrap and then released by heating under vacuum conditions. By using a proper MS inlet, the sorption tube can be rapidly emptied before the desorption of analytes, which greatly improves the sampling efficiency of direct introduction MS analysis and reduces the spectral interference of air background molecules. Effective enrichment of VOCs was achieved in the experiments such that the MS detection sensitivity for toluene was increased by 284 times with a sampling time of 2 min. Furthermore, a rough chromatographic separation effect was observed in the vacuum thermal desorption process, and the proposed sampling strategy also showed good quantitative ability in the direct MS analysis of VOCs.

Rotational electron-beam mastering (REBM) systems have been studied with the aim of achieving the high data density necessary to facilitate the fabrication of next-generation optical data media, such as holographic storage. This study reports the design and testing of an ionic liquid (IL)-lubricated hydrostatic spindle system comprising an IL bearing, IL supply pump, and ionic magnetic fluid seal; and its outgassing performance under high-vacuum conditions. An inner vacuum chamber pressure of approximately 10−4 Pa was maintained during rotation of the spindle system. The outgassed products, as measured by a quadrupole mass spectrometer, were primarily generated from the air components in the lubricant IL. The non-repeatable runout in the radial direction, which is an important parameter of REBM accuracy, was 100 nm for a rotational speed of less than 130 min−1. The proposed method can be used for a 100-nm scale REBM device.

Rationale Chloroform, a probable human carcinogen, is commonly detected in various concentration levels in many surface water and groundwater sources. Compound-specific chlorine stable isotope analysis (Cl-CSIA) is significant in investigating the fate of chlorinated contaminants in the environment. Analytical conditions should, however, be thoroughly examined for any isotopic fractionation. In this study, we simultaneously optimize three analytical parameters for a robust online Cl-CSIA of chloroform using the Taguchi design of experiments. Methods For Cl-CSIA, a purge-and-trap autosampler coupled to a gas chromatograph in tandem with a quadrupole mass spectrometer, with electron ionization in selected ion monitoring (SIM) mode, was used. Using the Taguchi method, the dominant parameter affecting the results of Cl-CSIA for chloroform was identified through concurrent investigation of the signal-to-noise ratios (S/N) of three parameters, each at three levels: purging time (5, 10, 15 min), transfer time (80, 120, 160 s), and dwell time (20, 60, 100 ms). Moreover, the optimum combination of the levels was identified. Results The purging time, with a maximum S/N, resulted in the highest influence on the isotope ratios determined. It was further refined through additional experiments to sufficiently extract chloroform from the aqueous phase. Accordingly, 8 min of purging time, 120 s transfer time and 100 ms dwell time were the optimum conditions for Cl-CSIA of chloroform. Post-optimization, a precision of ±0.28 ‰ was achieved for 8.4 nmol of chloroform (equivalent to 0.89 μg or approx. 25 nmol Cl-mass on column). Conclusions A simple online method for Cl-CSIA of chloroform was optimized with the Taguchi design of experiments. The Taguchi method was very useful for the optimization of the analytical conditions. However, the purging conditions should be fine-tuned and selected so that sufficient extraction of a target compound is confirmed to acquire a stable and higher precision of the method.

This study performed the calibration of QMG700 quadrupole mass spectrometer (QMS) against the ultrahigh vacuum (UHV) partial pressure standard. The research object was the sensitivity, noise level and minimum detectable partial pressure (MDPP) in the secondary electron multiplier (SEM) detector mode. This work was investigated in the SCAN and multiple ion detection (MID) operation modes, and scan speed and the dwell time were 50 ms/amu and 50 ms, respectively. The SEM voltage was changed in the range of (1100–3000) V. The experiment was carried out over the partial pressure range of 10−9 Pa to 10−7 Pa using He. The results demonstrated a significant correlation between the QMS metrological characteristics and its operation mode. This study was conducted according to the ISO TS 20175: 2018. The results showed a significant dependence between the metrological characteristics of QMS and its operation mode.

Aristolochic acid (AA) toxicity has been shown in humans regarding carcinogenesis, nephrotoxicity, and mutagenicity. Monitoring the AA content in drug homologous and healthy foods is necessary for the health of humans. In this study, a monoclonal antibody (mAb) with high sensitivity for aristolochic acid I (AA-I) was prepared. Based on the obtained mAb, a chemiluminescent immunoassay (CLEIA) against AA-I was developed, which showed the 50% decrease in the RLUmax (IC50) value of 1.8 ng/mL and the limit of detection (LOD) of 0.4 ng/mL. Carbon dots with red emission at 620 nm, namely rCDs, were synthesized and employed in conventional indirect competitive enzyme-linked immunosorbent assay (icELISA) to improve the assay sensitivity of a fluoroimmunoassay (FIA). Oxidized 3,3′′,5,5′′-tetramethylbenzidine dihydrochloride (oxTMB) can quench the emission of the rCDs through the inner-filter effect; therefore, the fluorescence intensity of rCDs can be regulated by the concentration of mAb. As a result, the assay sensitivity of FIA was improved by five-fold compared to CLEIA. A good relationship between the results of the proposed assays and the standard ultra-high performance liquid chromatography-triple quadrupole mass spectrometer (UPLC-QQQ-MS/MS) of real samples indicated good accuracy and practicability of CLEIA and FIA.

The proteomic analysis of the human brain tissue over the last decade has greatly enhanced our understanding of the brain. However, brain related disorders continue to be a major contributor of deaths around the world, necessitating the need for even greater understanding of their pathobiology. Traditional antibody-based techniques like western blotting or immunohistochemistry suffer from being low-throughput besides being labor-intensive and qualitative or semi-quantitative. Even conventional mass spectrometry-based shotgun approaches fail to provide conclusive evidence to support a certain hypothesis. Targeted proteomics approaches are largely hypothesis driven and differ from the conventional shotgun proteomics approaches that have been long in use. Multiple reaction monitoring is one such targeted approach that requires the use of a special mass spectrometer called the tandem quadrupole mass spectrometer or triple quadrupole mass spectrometer. In the current study, we have systematically highlighted the major steps involved in performing a successful tandem quadrupole mass spectrometry-based proteomics workflow using human brain tissue with an aim to introduce this workflow to a broader research community.

The present contribution describes analogies and differences between the quadrupolar ion trap (QIT) and the quadrupole mass analyzers, shows the potentialities of their combination in a single instrument and presents a review of applications of such a technology in different fields. The first section describes the quadrupole mass filter (QMF), outlining its principles of operation and the ion sorting procedure according to the use of oscillating electric fields inducing stable trajectories to the ions allowing them to reach the detector. Multiple quadrupole systems (normally triple quadrupoles) are then explained, showing their use in tandem mass spectrometry in space experiments (MS/MS-in-space). QIT principles of operation are then examined, pointing out that in this case the use of the same combination of oscillating electric fields takes advantage of unstable ion trajectories for their sorting. Substantially, analogies and differences between QMF and QIT come out, which consist in the fact that QMF is a scanning mass analyzer, whereas QIT is a sequential mass analyzer. In addition, the section underlines that QIT is capable to perform tandem mass spectrometry in time experiments (MS/MS-in-time). Later, the possibility to use a quadrupole as a trapping system with a prevailing dimension (linear ion trap [LIT]) is taken into consideration, and the possibility to combine both QMF and LIT in a single instrument, a QTrap mass spectrometer, is illustrated. In this frame, a lot more experiment types are possible with respect to both standalone triple quadrupoles and LIT, and they are described as well. Several combinations of these QTrap features can be used in information dependent acquisition (IDA) mode, allowing the high versatility of this instrumental configuration. The second section deals with a review of applications in different fields. These are organized by kind of QTrap and IDA features and cover different topics in biological, medical, agrochemical, nutritional and environmental fields.

Rapid screening for chemical traces of explosives and narcotics is widely used to support homeland security and law enforcement. These target compounds span a range of physicochemical properties from organic to inorganic, with preferential ionization pathways in both negative and positive mode operation. Nonvolatile inorganic oxidizers present in homemade fuel-oxidizer mixtures, pyrotechnics, and propellants create a unique challenge to traditional thermal desorption-based technologies. Developments in solid–liquid extraction techniques, specifically, open port sampling interface mass spectrometry (OPSI-MS) provide compelling capabilities to address these hurdles. In this proof of concept study, we investigated the trace detection of wipe-based (i.e., common swipe sampling collection method) explosives, oxidizers, and narcotics using an OPSI source and compact single quadrupole mass analyzer. The liquid dissolution and extraction capabilities of OPSI enabled detection of both traditional military-grade explosives and homemade explosive oxidizers. OPSI-MS sensitivities to a series of seven target compounds from polytetrafluoroethylene (PTFE) coated fiberglass sampling wipes were on the order of several nanograms to sub-nanogram levels. Comparisons with direct solution-based sample analysis enabled quantification of wipe-based sample extraction effects. The system demonstrated quick temporal responses, polarity switching capabilities, and rapid signal decay with minimal carryover, all critical to high throughput screening applications. Coupling traditional swipe sampling with OPSI-MS offers a promising tool for contraband screening applications.

18 pags., 5 figs., 2 tabs., Partial ionization cross section (PICS) measurements, of the cations created through electron ionization from threshold to 100 eV, have been taken for 78 cationic fragments of R-carvone, using a HIDEN quadrupole mass spectrometer (EPIC 300) with a mass resolution of 1 amu. These PICSs correspond to the cationic fragments with the highest intensity signal registered in our R-carvone mass spectrum reported in Lopes et al. (Int. J. Mass Spectrom. 456, 116395 (2020)) and, to the best of our knowledge, are being presented here for the first time to the scientific community. We also associate the profile observed in the PICSs with some ionic fragmentation mechanisms for R-carvone, based on the appearance energy (AE) values found in Lopes et al. Graphic abstract: [Figure not available: see fulltext.], This work was supported by the Brazilian Conselho Nacional de Desenvolvimento Cientıfico e Tecnologico (CNPq), Funda¸c˜ao de Amparo `a Pesquisa do Estado de Minas Gerais (FAPEMIG) and FINEP. M.C.A.L. acknowledges financial support from CNPq, while W.A.D.P., A.C.P.F. and R.A.A.A. acknowledge their fellowships from CAPES and FAPEMIG. Some financial assistance from the Australian Research Council through grant # DP180101655 is also noted. Finally, G. Garcıa thanks the Spanish Ministerio de Ciencia, Innovacion y Universidades for the project grants FIS 2016 -80440 and the CSIC project LINKA20085

The electron-induced reactivity of 5-(4-chlorophenyl)-1H-tetrazole and 5-chloro-1-phenyl-1H-tetrazole was studied using a trochoidal electron monochromator quadrupole mass spectrometer experimental setup. 5-(4-chlorophenyl)-1H-tetrazole underwent dissociative electron attachment to form Cl-, [M-HCl]-, and [M-H]-. 5-chloro-1-phenyl-1H-tetrazole underwent associative electron attachment to form the parent anion and dissociative electron attachment to form Cl-, CN2Cl-, [M-N2-Cl]-, and [M-HCl]-. For each anion product, the ion yield was measured as a function of incident electron energy. Density functional theory calculations were performed to support the experimental results with estimates of the energetic thresholds for the different reaction pathways. While the tetrazole group is susceptible to electron-induced ring opening in both molecules, this process was only observed for 5-chloro-1-phenyl-1H-tetrazole, indicating that this process is influenced by the structure of the molecule.

In this paper, a molecular pump unit was used to prepare a 316L stainless steel-quartz glass hybrid vacuum sealed tube with a background vacuum of 5×10-7 Pa. Based on a quadrupole mass spectrometer, we analyzed the vacuum preparation process and the residual gas dynamic composition and content when the background vacuum limit was reached. The ultimate vacuum of the sealed tube without high-temperature baking was about 5×10-5 Pa, and H2O was the residual gas with the highest partial pressure ratio. By further continuous high-temperature baking, it was possible to increase the ultimate vacuum to 3.7×10-7 Pa. At this time, the main residual gas components were H2, H2O, CH4, CO2, CO in a descending order, which was mainly released from the inner surface of the sealed tube, as well as gas attached to the filament of the mass spectrometer. The use of ion pump, sublimation pump and getter pump could further improve the background vacuum.

The ambient biogenic volatile organic compounds (BVOCs), mainly isoprene, are potentially involved in the formation of secondary pollutants, hence, they are significant in terms of air quality and climate. Although the largest sources of BVOCs are tropical regions, the measurements of isoprene in the Indian subcontinent are limited. We conducted the measurements of isoprene, benzene, and toluene at an urban site in a hillocky megacity of India using a high-sensitivity proton transfer reaction quadrupole mass spectrometer (PTR-QMS). The mixing ratios of isoprene were compared with those of aromatic compounds like benzene and toluene, which represent typical anthropogenic VOCs. Isoprene and isoprene/benzene (>5 ppbv ppbv−1) showed higher levels in the pre-monsoon months, most likely due to large emissions by urban vegetation during physiological activities in plants which was enhanced by the high ambient temperatures and solar radiation. While Benzene and toluene showed higher mixing ratios during winter, which were due to shallower boundary layer depths and transport of air masses from polluted Indo-Gangetic Plain during this season. The mixing ratios of VOCs show significant diurnal variation as a result of their different origins and the role of different meteorological parameters. The robust emission ratios of isoprene/benzene obtained from nighttime data were used to separate the non-anthropogenic and anthropogenic isoprene emissions. ∼30% enhancement observed in non-anthropogenic emissions to isoprene from winter to pre-monsoon season when temperatures and solar radiation were stronger, although traffic in the city. Isoprene/benzene ratio at lower temperatures ( 25 °C).

Eight polyhydroxy triterpenoid acids, hederagenin, (4α)-23-hydroxybetulinic acid, maslinic acid, corosolic acid, arjunolic acid, asiatic acid, caulophyllogenin, and madecassic acid, with 2, 3, and 4 hydroxyl substituents, were identified and quantified in the dichloromethane extract of Eucalyptus globulus wood by comparing their GC-retention time and mass spectra with standards. Two other triterpenoid acids were tentatively identified by analyzing their mass spectra, as (2α)-2-hydroxybetulinic acid and (2α,4α)-2,23-dihydroxybetulinic acid, with 2 and 3 hydroxyl substituents. Two MS detectors were used, a quadrupole ion trap (QIT) and a quadrupole mass filter (QMF). The EI fragmentation pattern of the trimethylsilylated polyhydroxy structures of these triterpenoid acids is characterized by the sequential loss of the trimethylsilylated hydroxyl groups, most of them by the retro-Diels-Alder (rDA) opening of the C ring with a π-bond at C12-C13. The rDA C-ring opening produces ions at m/z 320 (or 318) and m/z 278 (or 277, 276, 366). Sequential losses of the hydroxyl groups produce ions with m/z from [M - 90] to [M - 90*y], where y is the number of hydroxyl substituents present (from 2 to 4). Moreover, specific cleavage in ring E was observed, passing from m/z 203 to m/z 133 and conducting other major fragments such as m/z 189.

While the study of reactions between oppositely-charged ions has a long history, particularly within the context of plasmas and interstellar chemistry, the exploitation of such reactions for analytical applications was made possible with the advent of electrospray ionization (ESI). , ESI provides a means for generating abundant multiply-charged ions from a wide variety of molecular classes. It was then possible to use ESI to generate multiply-charged analyte or reagent ions for reactions with ions of opposite polarities without resulting in complete neutralization. The first description of ion/ion reaction studies using ESI was given by Loo et al. using a Y-tube reactor leading to the inlet of an atmosphere/vacuum interface coupled with a quadrupole mass filter. , This was an early example of ion/ion chemistry being effected prior to sampling ions into a mass spectrometer. The first implementation of ion/ion reactions within the context of a MSn experiment was demonstrated at Oak Ridge National Lab. , Thi...

This paper describes a single-laboratory validation of a liquid chromatography–diode array detection (LC–DAD) method for quantification of 12 major cannabinoids in Cannabis dried plant materials, concentrates, and oils. The method met Standard Method Performance Requirements for quantitative analysis of cannabinoids in Cannabis concentrates and Cannabis dried plant materials. The LOQs were in the range 0.003–0.10% (w/w), depending on the analyte and matrix. Spike recoveries were between 96.7 and 101.3% with relative SDs (RSDs) ≤2.3%. Precision expressed as repeatability and intermediate precision was within 0.3–4.8 and 1.1–5.1%, respectively. The chromatographic separation conditions used in this versatile method are compatible with both DAD–UV and MS detection. During method validation, high-resolution quadrupole time-of-flight MS was employed as a secondary detector (connected in series to the LC–DAD instrument) to provide high confidence identification of target analytes and as a tool for monitoring other cannabinoids for which reference standards were not available. The obtained results demonstrate applicability of the method to quantitative analysis of important cannabinoids in dried plants, concentrates, and oils. Limited data were generated for a food matrix (Cannabis-containing cookies) using this method with LC coupled to a compact single quadrupole mass spectrometer.

We have implemented a linear ion trap (LIT)-based SIM-stitching method for ultra-high-resolution Fourier transform mass spectrometry (FTMS) that increases the S/N over a wide m/z range compared to non-segmented wide full-scan (WFS) spectra. Here we described an improved segmented spectral scan stitching method that was based on quadrupole mass filter (QMF)-SIM, which overcame previous limitations of ion signal loss in LIT. This allowed for accurate representation of isotopologue distributions, both at natural abundance and in stable isotope-resolved metabolomics (SIRM)-based experiments. We also introduced a new spectral binning method that provided more precise and resolution-independent bins for irreversibly noise-suppressed FTMS spectra. We demonstrated a substantial improvement in S/N and sensitivity (typically > 10-fold) for 13C labeled lipid extracts of human macrophages grown as three-dimensional (3D) cell culture, with detection of an increased number of 13C isotopologue ions. The method also enabled analysis of extracts from very limited biological samples.

Sampling and extraction of chemical residues present on flat or curved surfaces as well as touch-sensitive objects are challenging. Hydrogels are characterized by high mechanical flexibility and water content. Thus, they are an ideal medium for transferring water-soluble analytes from a sampled surface to the next stage of an analytical workflow. Here, we demonstrate gel-phase microextraction (GPME), in which disks of blended hydrogels are utilized to lift traces of water-soluble substances adsorbed on surfaces. The protocol has been optimized in a series of tests involving fluorometric and mass spectrometric measurements. Compared with the pure agarose hydrogel, most of the tested blended hydrogels provide a higher efficiency for the sampling/extraction of a model analyte, fluorescein. The blended hydrogel disks are incorporated into three-dimensional (3D)-printed acrylonitrile–butadiene–styrene chips to create easy-to-use sampling probes. We exemplify the suitability of this improved GPME approach in sampling chemical residues present on the skin, glass, and daily use objects. In these tests, the extracts were analyzed on a triple quadrupole mass spectrometer fitted with an electrospray ion source operated in the positive- and negative-ion modes. The method enabled the detection of diclofenac on excised porcine skin fragments exposed to a topical nonsteroidal anti-inflammatory drug and sweat residues (lactic acid) left on surfaces touched by humans. The limits of detection for diclofenac and lactic acid in hydrogel extract were 6.4 × 10–6 and 2.1 × 10–5 M, respectively. In a model experiment, conducted using the presented approach, the amount of lactic acid on a glass slide with fingerprints was estimated to be ∼1.4 × 10–7 mol cm–2.

Phosphorothioate oligonucleotide drugs typically contain product-related impurities that are difficult to resolve chromatographically from the parent oligonucleotide due to the size of these compounds and the large number of stereoisomers that comprise the parent. The presence of co-eluting impurities hinders the process of determining assay based on chromatographic separation alone. A mass spectrometry-based purity assessment of the main chromatography peak can be used to quantify co-eluting impurities and enable the accurate determination of assay, but a more direct measure of assay was desired due to the complexity of measuring all co-eluting impurities by mass spectrometry. Therefore, we developed an assay method that utilizes the specificity of mass spectrometry to measure the amount of active pharmaceutical ingredient in a sample, which eliminates the need for chromatographic separation of impurities from the product. This procedure uses a single quadrupole mass spectrometer and incorporates an internal standard that is co-sprayed with the analyte to compensate for the drift commonly associated with mass spectrometry-based quantitation. Using the mass spectrometry response ratio for sample to internal standard enables the method to achieve excellent linearity (R2 = 0.998), repeatability (relative standard deviation = 0.5%), intermediate precision (0.6%), and accuracy, with measured assay values consistently within 2.0% of expected. The results indicate the method possesses the accuracy and precision required for measuring assay in clinical and commercial stage pharmaceutical products. Since the method is based on the specificity of the mass spectrometer, and does not rely on chromatographic separation of impurities, the procedure should be applicable to a wide variety of oligonucleotide therapeutics regardless of sequence or chemical modifications.

The ion energy distribution and average energy of Ar/O2 mixed gas discharge have been studied using quadrupole mass spectrometer. The results show that the potential increases in the sheath, the ions obtain higher energy through the sheath, high energy peak moves to high energy area and the energy width increases as low-frequency power increases, which is consistent with the theoretical model calculation results. When pressure rises, collisions of Ar+ ions are more frequent in the process of crossing the sheath, the bimodal structure becomes vaguely, and under the same condition the number of low energy ions increases gradually.

In fusion devices, the retention of the fusion fuel deuterium (D) and tritium (T) in plasma-facing components (PFCs) is a major concern. Measurement of their hydrogen isotope content gives insight into the retention physics. In FREDIS, two methods of thermal desorption are used for retention measurements: In Thermal Desorption Spectrometry (TDS) the samples are heated by 6 infrared lamps up to 1433 K with linear temperature ramps of up to 1.67 K/s. The desorbed gases are detected up to 100 amu/e with a double-QMS (Quadrupole Mass Spectrometer) that can distinguish between helium and D2 and uses an innovative differential pumping system. In a connected vacuum chamber, a ∅3 mm spot can be heated on the sample surface by a high energy Nd:YAG laser pulse (E0