Mass Spectra Of Products Research Articles

Oscillations of {B}_s^0 Mesons as a Probe of Decays with Unreconstructed Particles

A new experimental technique to study the decays of {B}_s^0 mesons into final states involving unreconstructable particles is proposed. The method uses a characteristic feature of fast flavour oscillations of {B}_s^0 mesons. Analysis of the oscillation-frequency spectrum of partially reconstructed flavour-tagged {B}_s^0 decays provides information about the mass spectrum of unreconstructed decay products and suppresses any background that does not come from the decays of {B}_s^0 mesons.

Влияние концентрации допанта (Eu/Nd) на физико-химические свойства оксигидроксида иттрия

In this paper we have studied the influence of europium and neodymium concentration, added to a water solution in the salt form, on the properties of yttrium oxyhydroxide, which was synthesized via the sol-gel route, using yttrium nitrate as a precursor. By synchronous thermal analysis it has been found that ions of europium and neodymium interact with yttrium oxyhydroxide in different ways, but in every case the thermoanalytical curves and mass spectra of gaseous thermolysis products (18, 30, 44 mass/charge) become more complicated. It is clear that europium and neodymium affect not only the phase composition and luminescent properties, but also the yttrium oxyhydroxide precipitation. For neodymium, its content in the precipitate is lower than in the initial solution; for europium, a different tendency is characteristic and its amount in the precipitate is greater than in the solution, i. e., it prevents the transfer of polymer particles of yttrium oxyhydroxide into the solid phase. By the method of X-ray phase analysis, the shift of the peaks in the diffraction patterns of relatively undoped yttrium oxyhydroxide by 5…7° has been revealed, which indicates the partial introduction of dopants into the crystalline formations of yttrium oxyhydroxide. The EDX and SEM methods reveal that both dopants are uniformly distributed in the matrix of materials. Neodymium-doped materials form coarse particles, while europium-doped ones form more finely dispersed spherical and lamellar particles (subject to dopant quantity). Materials possess luminescence properties in UV range with maximum at 300 nm and can be applied as luminophores in sunlamps.

Метод записи и воспроизведения эксперимента по исследованию свойств полевых эмиттеров на основе углеродных нанотрубок

A method for recording and emulating a complex experiment in field emission was developed. The method includes processing of three types of data streams: data on the electrical characteristics of the field cathode (voltage and current pulses), data on the field emission projector (glow patterns) and time-of-flight mass spectrometer data (mass spectra of volatile products in the measuring chamber). The LabView software environment implements an algorithm for synchronous reproduction of multichannel experiment data with the possibility of processing it in real time. The program has a built-in set of software tools that implement the functionality and repeat the experiment many times, pause at specified points in time, as well as change the time flow rate in the emulation. The capabilities of the method are demonstrated by the example of studying field emission from a nanocomposite field cathode based on carbon nanotubes.

Quantification of Cytokinins Using High-Resolution Accurate-Mass Orbitrap Mass Spectrometry and Parallel Reaction Monitoring (PRM).

Cytokinins (CKs) are adenine derivatives that act as phytohormones. These signaling molecules control plant cell division and differentiation, organ growth, and senescence, and they orchestrate plant interactions with biotic and abiotic environments. While CKs are predominately recognized as plant-based substances, CKs have been found across different domains of life, including microorganisms, insects, mammals, and humans. In plants, CKs act at trace, often low femtomolar concentrations; therefore, sensitive and precise analytical techniques are required to accurately detect and quantify them from complex biological matrices. Here, we report the first comprehensive CK quantification method using a QExactive Orbitrap mass spectrometer in high-resolution with a parallel reaction monitoring (PRM)-based approach. The current method progresses upon multiple reaction monitoring (MRM) methods, previously used for CK profiling on triple quadrupole mass spectrometers. This method offers improved mass accuracy and the complete product ion mass spectra (MS/MS) for compound determination with increased specificity, and sensitivity comparable with triple quadrupole instruments. The presented PRM approach was successfully applied to quantify 32 CKs in several biological samples.

Two-Dimensional Tandem Mass Spectrometry in a Single Scan on a Linear Quadrupole Ion Trap.

A two-dimensional tandem mass spectrometry (2D MS/MS) scan has been developed for the linear quadrupole ion trap. Precursor ions are mass-selectively excited using a nonlinear ac frequency sweep at constant rf voltage, while simultaneously, all product ions of the excited precursor ions are ejected from the ion trap using a broad-band waveform. The fragmentation time of the precursor ions correlates with the precursor m/z value (the first mass dimension) and also with the ejection time of the product ions, allowing the correlation between precursor and product ions. Additionally, the second mass dimension (product ions' m/z values) is recovered through fast Fourier transform of each mass spectral peak, revealing either intentionally introduced "frequency tags" or the product ion micropacket frequencies, both of which can be converted to product ion m/z through the classical Mathieu parameters, thereby revealing a product ion mass spectrum for every precursor ion without prior isolation. We demonstrate the utility of this method for analyzing a broad range of structurally related precursor ions, including chemical warfare agent simulants, fentanyls and other opioids, amphetamines, cathinones, antihistamines, and tetracyclic antidepressants.

Liquid chromatography–tandem mass spectrometry screening method using information‐dependent acquisition of enhanced product ion mass spectra for synthetic cannabinoids including metabolites in urine

The total number of synthetic cannabinoids (SCs) - a group of new psychoactive substances (NPS) - is increasing every year. The rapidly changing market demands the latest analytical methods to detect the consumption of SCs in clinical or forensic toxicology. In addition, SC metabolites must also be included in a screening procedure, if detection in urine is asked for. For that purpose, an easy and fast qualitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) urine screening method for the detection of 75 SCs and their metabolites was developed and validated in terms of matrix effects, recovery, and limits of identification for a selection of analytes. SC metabolites were generated using in vitro human liver microsome assays, identified by liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) and finally included to the MS/MS spectra in-house library. Sample preparation was performed using a cheap-and-easy salting-out liquid-liquid extraction (SALLE) after enzymatic hydrolysis. Method validation showed good selectivity, limits of identification down to 0.05ng/mL, recoveries above 80%, and matrix effects within ±25% for the selected analytes. Applicability of the method was demonstrated by detection of SC metabolites in authentic urine samples.

Diagnosis of Hemoglobinopathy and β-Thalassemia by 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Tandem Mass Spectrometry of Hemoglobin from Blood.

Hemoglobinopathies and thalassemias are the most common genetically determined disorders. Current screening methods include cation-exchange HPLC and electrophoresis, the results of which can be ambiguous because of limited resolving power. Subsequently, laborious genetic testing is required for confirmation. We performed a top-down tandem mass spectrometry (MS/MS) approach with a fast data acquisition (3 min), ultrahigh mass accuracy, and extensive residue cleavage by use of positive electrospray ionization 21 Tesla Fourier transform ion cyclotron resonance-tandem mass spectrometry (21 T FT-ICR MS/MS) for hemoglobin (Hb) variant de novo sequencing and β-thalassemia diagnosis. We correctly identified all Hb variants in blind analysis of 18 samples, including the first characterization of homozygous Hb Himeji variant. In addition, an Hb heterozygous variant with isotopologue mass spacing as small as 0.0194 Da (Hb AD) was resolved in both precursor ion mass spectrum (MS1) and product ion mass spectrum (MS2). In blind analysis, we also observed that the abundance ratio between intact δ and β subunits (δ/β) or the abundance ratio between intact δ and α subunits (δ/α) could serve to diagnose β-thalassemia trait caused by a mutation in 1 HBB gene. We found that 21 T FT-ICR MS/MS provides a benchmark for top-down MS/MS analysis of blood Hb. The present method has the potential to be translated to lower resolving power mass spectrometers (lower field FT-ICR mass spectrometry and Orbitrap) for Hb variant analysis (by MS1 and MS2) and β-thalassemia diagnosis (MS1).

NPS: scoring and evaluating the statistical significance of peptidic natural product-spectrum matches.

MotivationPeptidic natural products (PNPs) are considered a promising compound class that has many applications in medicine. Recently developed mass spectrometry-based pipelines are transforming PNP discovery into a high-throughput technology. However, the current computational methods for PNP identification via database search of mass spectra are still in their infancy and could be substantially improved.ResultsHere we present NPS, a statistical learning-based approach for scoring PNP–spectrum matches. We incorporated NPS into two leading PNP discovery tools and benchmarked them on millions of natural product mass spectra. The results demonstrate more than 45% increase in the number of identified spectra and 20% more found PNPs at a false discovery rate of 1%.Availability and implementationNPS is available as a command line tool and as a web application at http://cab.spbu.ru/software/NPS.Supplementary information Supplementary data are available at Bioinformatics online.

Differentiation of o-, m-, and p-fluoro-α-pyrrolidinopropiophenones by Triton B-mediated one-pot reaction

Positional isomer differentiation is crucial for the analysis of forensic drugs. Presently, it is difficult to distinguish among ortho, meta, and para positional isomers of ring-fluorinated synthetic cathinones, a major class of new psychoactive substances (NPSs), because they exhibit similar chromatographic properties and mass spectral patterns. We describe herein that the ring-fluorinated synthetic cathinone positional isomers, viz. o-, m-, and p-fluoro-α-pyrrolidinopropiophenones (o-, m-, and p-FPPPs), can be discriminated by their benzyltrimethylammonium hydroxide (Triton B)-mediated one-pot reaction with methanol at ambient temperature, followed by chromatographic and mass spectral analyses of the corresponding products. For p-FPPP, fluorine was nucleophilically substituted by the methoxy group to afford p-methoxy-α-pyrrolidinopropiophenone, while o- and m-FPPPs afforded the corresponding FPPP-enamine–pyrrolidine adducts, which allowed the above positional isomers to be unambiguously differentiated by comparing the reaction product chromatograms and mass spectra. The adopted approach, which does not require excess heating or use of metallic catalysts and features the advantages of simplicity and convenience, is expected to contribute toward practical NPS identification.

State-Dependent Fragmentation of Protonated Uracil and Uridine.

Action spectroscopy using photon excitation in the VUV range (photon energy 4.5-9 eV) was performed on protonated uracil (UraH+) and uridine (UrdH+). The precursor ions with m/ z 113 and m/ z 245, respectively, were produced by an electrospray ionization source and accumulated inside a quadrupole ion trap mass spectrometer. After irradiation with tunable synchrotron radiation, product ion mass spectra were obtained. Fragment yields as a function of excitation energy show several maxima that can be attributed to the photoexcitation into different electronic states. For uracil, vertically excited states were calculated using the equation-of-motion coupled cluster approach and compared to the observed maxima. This allows to establish correlations between electronic states and the resulting fragment masses and can thus help to disentangle the complex de-excitation and fragmentation pathways of nucleic acid building blocks. Photofragmentation of the nucleoside uridine shows a significantly lower variety of fragments, indicating stabilization of the nucleobase by the attached sugar.

Quantification of fosamprenavir in spiked human plasma using liquid chromatography–electrospray ionization–tandem mass spectrophotometry–application to pharmacokinetic study

Background Fosamprenavir (FSV) is used for the treatment of HIV infections. It is a prodrug of the protease inhibitor and antiretroviral drug amprenavir. Aim This research work described about the estimation of FSV in spiked human plasma using electrospray ionization, LC-MS/MS technique, and its application to pharmacokinetic study in rabbits. Materials and methods Liquid–liquid extraction technique was used for the extraction of FSV in spiked human plasma. The separation was achieved using ZORBAX SB-C18 column with 4.6 mm internal diameter with 5 μm particle size using acetonitrile: 5 mmol/l ammonium acetate in water (85 : 15, v/v) as a mobile phase. Positive ion mode was selected for the product ion mass spectra, m/z 585.6–418.2 for FSV and m/z 589.2–469.1 for FSV-deuterated (internal standard), The US Food and Drug Administration guidelines were adopted for successful validation of the developed method. Results The retention time of FSV was found to be 1.51 min, for FSV-deuterated it was 1.62 min, with a runtime of 2.5 min. The present method exhibits excellent intraday and interday accuracy with %nominal 95–98.4% and precision percentage coefficient variation up to 3% in all quality control (QC) levels. The developed method demonstrated excellent matrix and analyte selectivity (%interference=0), matrix effect (matrix factor 2.09 at lower quantitation limit and 1.14 at high QC level) and satisfactory stability study results in all types (%nominal 94.03–100.80%). The linearity range was found to be 0.510–200.185 ng/ml with a correlation coefficient (r2) of 0.998. The calculated accuracy and precision values in the ruggedness study were within 15–20% in all QC levels. The percentage coefficient variation of the pharmacokinetic study on rabbit plasma samples was also conducted and the parameters of FSV showed Tmax of 2 h and the mean Cmax, AUC0→t and AUC0→α for test formulation were 98.6, 351.3, and 354.9, respectively. Conclusion This method was successfully optimized, validated, and applied favorable for the pharmacokinetic study of marketed formulation in rabbit blood samples in a single oral human-equivalent dose. The applicability of the developed method undoubtedly can further extend during preclinical and clinical trials.

Heavy Ion Composition of Mercury's Magnetosphere

AbstractWe modeled the exospheric densities for sputtering and thermal desorption in detail for the time period of the first MESSENGER flyby of Mercury. From the exospheric densities we calculate ion production rates. These ions will be transported to the location of MESSENGER if they are produced on magnetic field lines connecting the cusp with the downwind side. From these ions we produce mass spectra that we compared with the Fast Imaging Plasma Spectrometer measurements performed during this flyby. We find good qualitative agreement between the modeled and the measured ion mass spectrum. We find that sputtering is a major process to contribute to the population of planetary ions in the magnetosphere because of the large scale height of the exospheric particles and the resulting long flight times. In addition, thermal desorption of Na contributes significant amounts to the magnetospheric ion population. From the volatile species we can identify He, OH, H2O, and Ne in the measured mass spectrum. However, for most of the volatile species the reported upper limits must be reduced by 2–3 orders of magnitude to be compatible to the measured ion spectrum.

Evaluation of gas chromatography-atmospheric pressure chemical ionization tandem mass spectrometry as an alternative to gas chromatography tandem mass spectrometry for the determination of polychlorinated biphenyls and polybrominated diphenyl ethers

A method for the analysis of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in serum was developed using gas chromatography coupled to tandem mass spectrometry with atmospheric pressure chemical ionization (GC-APCI-MS/MS). The ionization and fragmentation performance of APCI were evaluated and compared with those of electron ionization (EI). In contrast to extensive fragmentation caused by EI with high energy, soft ionization achieved by APCI produced mass spectra dominated by molecular ions from the first stage of MS analysis. Better sensitivity and selectivity achieved by the GC-APCI-MS/MS method allowed to analyze serum samples with a low volume (100 μL). The limits of detection (LODs) ranged from 0.067 to 14 pg/mL for the analysis in serum samples. The developed method was evaluated at three spiking levels (0.05, 0.5 and 5 ng/mL for PCBs), showing good recoveries and repeatability. The recoveries ranged from 74.0% to 130.5%, and the relative standard deviations (RSDs) were less than 20%, for all analytes. The determination of PCBs and PBDEs in the human serum samples by GC-APCI-MS/MS was compared with gas chromatography-tandem mass spectrometry with EI (GC-EI-MS/MS). BDE-99 and BDE-100 were successfully quantified by GC-APCI-MS/MS, while these two PBDE congeners were not detected by GC-EI-MS/MS. The GC-APCI-MS/MS method had a clear advantage when analyzing compounds at low levels.

Pyrolysis study of Huainan coal with different particle sizes using TG analysis and online Py-PI-TOF MS

The pyrolysis behaviors of Huainan coal (HN coal) with three particle sizes, i.e., <40 μm (HN-S), 224–500 μm (HN-M) and 1600–2000 μm (HN-L), were investigated by thermogravimetry (TG) and online pyrolysis photoionization time-of-flight mass spectrometry (Py-PI-TOF MS) using a krypton discharge lamp (10.6 eV) and synchrotron radiation vacuum ultraviolet light (SVUV) (14.2 eV and 15.5 eV) as the ionization sources. The fragment-free mass spectra of coal pyrolysis products were obtained at 600 °C in real time. The released organic volatiles were characterized as alkenes, phenols and aromatics, and their evolved profiles were measured as a function of time in fixed temperature mode and as a function of temperature in programmed-temperature mode. A higher weight loss ratio of the TG curves was obtained when the particle size was increased. The intensities of the individual volatiles in the mass spectra were all enhanced following the increase in the particle size of HN coal. With regard to the time-evolved profiles, by increasing the particle size, the appearance times of volatiles were delayed. Tricyclic aromatics showed multireleasing processes in both time-evolved and temperature-programmed profiles. The release of the guest molecules lagged within the higher temperature region as the coal particle size increased. To explain the evolution trends of most organic volatiles, a mechanism combining intraparticle and interparticle mechanisms is presented.

Analysis of Microbial Siderophores by Mass Spectrometry.

Siderophores represent important microbial virulence factors and infection biomarkers. Their monitoring in fermentation broths, bodily fluids, and tissues should be reproducible. Similar isolation, characterization, and quantitation studies can often have conflicting results, and without proper documentation of sample collection, data processing, and analysis methods, it is difficult to reexamine the data and reconcile these differences. In this Springer Nature Protocol, we present the procedure optimized for ferricrocin/triacetylfusarinine C extraction from biological material as well as for tissue fixation and cryosectioning for optical microscopy and for both elemental and molecular mass spectrometry imaging. Special attention is paid to siderophore data mining from conventional and product ion mass spectra, liquid chromatography, and mass spectrometry imaging datasets, performed here by our free software called CycloBranch.

Exposure marker discovery of di-2(propylheptyl) phthalate using ultra-performance liquid chromatography-mass spectrometry and a rat model

Di-(2-propylheptyl) phthalate (DPHP) is a plasticizer and has been suggested to be a subchronic toxicant in rats. DPHP has been approved to be used in food containers and handling by the U.S. Food and Drug Administration. The use of DPHP is still increasing, and the risk of human exposure to DPHP via food may be high. Exposure markers measured in human samples are commonly used to monitor human exposure levels. Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and a rat model were used to discover tentative DPHP exposure markers. DPHP and mono-(2-propylheptyl) phthalate (MPHP) were used as the precursors for calculating metabolite candidates using biotransformation mass changes of known enzymatic reactions. A rat model was designed to validate these metabolite candidates as tentative exposure markers. A total of 28 signals show dose–response relationships and these signals contain a few isomers. The chemical structures of 15 tentative exposure marker signals were speculated based on the product ion mass spectra from MS/MS analysis. These 15 signals included 7 chemical structures and some of them may be isomers. The different arrangement of the atoms in space of these isomers should be validated by standard compounds in the future studies. Among the 7 speculated chemical structures, 2 structures were novel tentative DPHP metabolites, and 5 structures have been previously reported in the literature. The results indicate that using UPLC-MS and a rat model can be used to identify tentative toxicant exposure markers.

A machine learning approach to aerosol classification for single-particle mass spectrometry

Abstract. Compositional analysis of atmospheric and laboratory aerosols is often conducted via single-particle mass spectrometry (SPMS), an in situ and real-time analytical technique that produces mass spectra on a single-particle basis. In this study, classifiers are created using a data set of SPMS spectra to automatically differentiate particles on the basis of chemistry and size. Machine learning algorithms build a predictive model from a training set for which the aerosol type associated with each mass spectrum is known a priori. Our primary focus surrounds the growing of random forests using feature selection to reduce dimensionality and the evaluation of trained models with confusion matrices. In addition to classifying ∼20 unique, but chemically similar, aerosol types, models were also created to differentiate aerosol within four broader categories: fertile soils, mineral/metallic particles, biological particles, and all other aerosols. Differentiation was accomplished using ∼40 positive and negative spectral features. For the broad categorization, machine learning resulted in a classification accuracy of ∼93 %. Classification of aerosols by specific type resulted in a classification accuracy of ∼87 %. The “trained” model was then applied to a “blind” mixture of aerosols which was known to be a subset of the training set. Model agreement was found on the presence of secondary organic aerosol, coated and uncoated mineral dust, and fertile soil.

CycloBranch: An open tool for fine isotope structures in conventional and product ion mass spectra.

Within the growing community of Fourier transform mass spectrometry users, the identification of fine isotope structure has become an indispensable method for molecular formula determination. In this work, the fine isotope envelopes for accessing the mutual ratio of 2 closely related pyoverdines in a mixture were used. Bacterial siderophores pyoverdines D and E cannot be easily separated via liquid chromatography-mass spectrometry because their structures differ in (de)amidation at the respective chromophore parts only. Their mutual ratio was determined in a mixture via nuclear magnetic resonance spectroscopy and semiquantitative mass spectrometry using our open-source software CycloBranch, which represents a genuine free tool supporting the determination of fine isotope structures in both conventional and product ion mass spectra. Native Bruker, Thermo, and Waters data formats are supported in addition to XML and plain text formats.

Vacuum Matrix-Assisted Ionization Source Offering Simplicity, Sensitivity, and Exceptional Robustness in Mass Spectrometry.

Vacuum matrix-assisted ionization (vMAI) uses select matrix compounds which when exposed to the vacuum of a mass spectrometer produce gas-phase ions from associated volatile or nonvolatile analyte without external energy input. Here, a vMAI source was constructed to replace the commercial inlet of a Thermo Orbitrap mass spectrometer. This allowed for rapid introduction of the matrix/analyte sample by a probe, contrary to vacuum matrix-assisted laser desorption/ionization (MALDI) sources. The matrix/analyte sample is inserted into a region of the "S-lens" entrance, where the spontaneously formed ions can be effectively transferred to the mass analyzer. This specifically designed ion source requires no laser, high voltage, heat, or nebulizing gases. A low voltage is used to transmit the ions through the commercial "S-lens" assembly and airflow can be used to modulate the ionization event. A few picograms of the drug erythromycin, assisted by the 3-nitrobenzonitrile vMAI matrix, is sufficient to produce mass spectra for over 1 min with the MH+ ion as the base peak in each mass spectrum. There is minimal carryover when loading high concentration samples and complex mixtures, contrary to direct infusion electrospray ionization, providing the probe is thoroughly cleaned between each new sample acquisition. Analyses of biological fluids, bacterial extracts, tissue, and high concentration samples have so far shown no indication of inlet or instrument contamination with these samples. The typical ultrahigh resolution and mass accuracy of the mass spectrometer are achieved, and a path forward to potential high throughput acquisitions demonstrated. It is expected that robustness can be introduced to any mass spectrometer through implementation of such a simple source.

Identification of a freshness marker metabolite in stored soybean sprouts by comprehensive mass-spectrometric analysis of carbonyl compounds

The objective of this study was to identify metabolites that quantitatively indicate degrees of freshness of soybean sprouts. Self-cultivated soybean sprouts were stored at 5 °C, 10 °C or 20 °C, and respiratory CO2 production rates were monitored using gas chromatography during storage. Carbonyl compounds (CCs) were analyzed comprehensively using mass-spectroscopic metabolomics analyses. CCs were derivatized using dansyl hydrazine (DH) and were then analyzed using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS) with multiplexed multiple reaction monitoring (MRM). In the MRM chromatogram, 171 to 358 peaks were observed from stored soybean sprouts. Principle component analysis and discriminant analysis (PCA-DA) selected the CC-DH derivative ion with a m/z 512 at a retention time of 9.34 min as the most significant metabolite. Searching online metabolomics databases and matching fragment patterns of product ion mass spectra of an authentic standard revealed abscisic acid is a freshness marker of soybean sprouts.