Time-of-flight Mass Spectrometry Research Articles

Formation analysis of primary and secondary metabolites during angkak fermentation based on GC-TOF-MS, GC-FID, and HPLC and metabolomics analysis

The significant primary and secondary metabolites occurred during angkak fermentation are composed of organic acids, amino acids, monacolin K, pigments, and citrinin (a mycotoxin), which their variance is able to inform how the Monascus-fermented produce characteristics. Here, gas chromatography time of flight mass spectrometry (GC-TOF-MS), gas chromatography-flame ionization detector (GC-FID), and high-performance liquid chromatography (HPLC) were utilized for analysis of the metabolites in angkak (Monascus purpureus) for 30 days. Principal component analysis (PCA) and Pearson’s correlation coefficients were to study the relationship between the metabolites and fermentation time. Moreover, the metabolomics analysis in angkak was performed by using MetaboAnalyst 5.0. The amount of primary metabolites such as the organic acids (succinic acid, glycolic acid, oxalic acid, lactic acid, lactobionic acid, and pyruvic acid), amino acids (valine, isoleucine, and alanine), fatty acids (stearic acid, oleic acid, linoleic acid, palmitic acid, and linolenic acid), and, monosaccharides (i.e. fructose and glucose) increased gradually until 15 days of the fermentation and then would decrease (the death phase of M. purpureus). For the secondary metabolites, the levels of monacolin K, Monascus pigments, and citrinin (a mycotoxin)after day 10 of the fermentation increased more than 2 times as compared with the previous fermentation time of day 5, exposing to begin the stationary phase of M. purpureus growth. Similarly, according to the heat map of primary metabolites’ production rates, there were their higher production rates of primary metabolites after 10 and 15 days of the fermentation; whereas, the higher production rates of secondary metabolites were found after 25 and 30 days of the fermentation. The PCA and Pearson’s correlation coefficients explained that the primary and secondary metabolites were discriminated completely into different groups. Based on the data of 19 metabolites throughout 30 days of the fermentation, there were estimated 23 metabolisms, but outstanding 4 metabolisms were glycolysis, pyruvate metabolism, α-linolenic acid metabolism, and linoleic acid metabolism.

Development and Application of a Chemical Ionization Focusing Integrated Ionization Source TOFMS for Online Detection of OVOCs in the Atmosphere.

Single photon ionization (SPI) based on vacuum ultraviolet (VUV) lamps has been extensively investigated and applied due to its clean mass spectra as a soft ionization method. However, the photon energy of 10.6 eV and photon flux of 1011 photons s-1 of a commercial VUV lamp limits its range of ionizable analytes as well as its sensitivity. This work designs a chemical ionization focusing integrated (CIFI) ionization source time-of-flight mass spectrometry (TOFMS) based on a VUV lamp for the detection of volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs). The photoelectrons obtained from the VUV lamp via the photoelectric effect ionized the oxygen and water in the air to obtain the reagent ions. The ion-molecule-reaction region (IMR) is constituted by a segmented quadrupole that radially focuses the ions using a radio-frequency electric field. This significantly enhances the yield and transport efficiency of the product ions leading to a great improvement in sensitivity. As a result, a 44-fold and 1154-fold increase in the signal response for benzene and pentanal were achieved, respectively. To verify the reliability of the ionization source, the linear correspondence and repeatability of benzene and pentanal were investigated. Satisfactory dynamic linearity was obtained in the mixing ratio range of 5-50 ppbv, and the relative standard deviation (RSD) of inter-day reached 3.91% and 6.26%, respectively. Finally, the CIFI-TOFMS was applied to the determination of OVOCs, and the LOD of 12 types of OVOCs reached the pptv level, indicating that the ionization source has the potential for accurate and sensitive online monitoring of atmospheric OVOCs.

Phenolphthalein based molecule as a lighting–up fluorescent chemoprobe for the nanomolar recognition of Al3+: DFT study and its applications in test kits, food and water samples

Phenolphthalein–based compound (PHAB) was synthesized, well–characterized and studied as a lighting–up fluorescent chemosensor for Al3+. Fluorescence studies were performed at 25 °C in H2O/CH3CN (20/80, v/v) media. Free PHAB was non–fluorescent; but, it depicted a strong fluorescence toward Al3+ at 468 nm over potential competitive cations. The mechanism of C = N isomerisation and blocking PET enhanced its emission with a remarkable color alteration from colorless to blue. The LOD value was found at nano–molar level (51.5 nM), indicating high sensitivity toward Al3+. The validation study also confirmed the sensing performance of PHAB based on different analytical parameters. Job's plot, 1H NMR titration and MALDI TOF–MS studies authenticated the stoichiometry between PHAB and Al3+ (1:2). The binding of PHAB with Al3+ was further verified by the theoretical study. Furthermore, the fluorescence sensing performance of PHAB makes it perfect for practical applications in drinkable water and food samples with satisfactory recovery values (91.42%–108.8%), as well as in simple test–kit applications.

Chemical composition and antioxidant activity of different parts of Prunella vulgaris by UPLC-Q-TOF-MS/MS and UPLC

Prunellae Spica is the dried spica of Prunella vulgaris belonging to Labiatae and it is widely used in pharmaceutical and general health fields. As a traditional Chinese medicine cultivated on a large scale, it produces a large amount of non-medicinal parts, which are discarded because they are not effectively used. To analyze the chemical constituents in the different samples from spica, seed, stem, and leaf of P. vulgaris, and explore the application value and development prospect of these parts, this study used ultrahigh performance liquid chromatography-tandem quadrupoles time of flight mass spectrometry(UPLC-Q-TOF-MS/MS) to detect chemical constituents in different parts of P. vulgaris. As a result, 117 compounds were detected. Among them, 87 compounds were identified, including 32 phenolic acids, 8 flavonoids, and 45 triterpenoid saponins. Some new triterpenoid saponins containing the sugar chain with 4-6 sugar units were found. Further, multivariate statistical analysis was conducted on BPI chromatographic peaks of multiple batches of different parts, and the results showed that spica had the most abundant chemical constituents, including salviaflaside and linolenic acid highly contained in the seed and phenolic acids, flavonoids, and triterpenoid saponins in the stem and leaf. In general, the constituents in the spica were composed of those in the seed, stem, and leaf. UPLC was used to determine the content of 6 phenolic acids(danshensu, protocatechuic acid, protocatechuic aldehyde, caffeic acid, salviaflaside, and rosmarinic acid) in different parts. The content of other phenolic acids in the seed was generally lower than that in the spica except that of salviaflaside. The content of salviaflaside in the spica was higher than that in the stem and leaf, but the content of other phenolic acids in the spica was not significantly different from that in the stem. The content of protocatechuic aldehyde and caffeic acid in the spica was lower than that in the leaf. DPPH free radical scavenging method was used to detect the antioxidant activity of four parts, and there was no significant difference in the antioxidant activity between the spica and the stem and leaf, but that was significantly higher than the seed. Moreover, the antioxidant activity of these parts was correlated with the content of total phenolic acids. Based on the above findings, the stem and leaf of P. vulgaris have potential application value. Considering the traditional medication rule, it is feasible to use the whole plant as a medicine. Alternatively, salviaflaside, occurring in the seed, can be used as a marker compound for the quality evaluation of Prunellae Spica, if only using spica as the medicinal part of P. vulgaris, as described in the Chinese Pharmacopoeia(2020 edition).

New steroidal saponins from aerial parts of Paris polyphylla var. chinensis

The shortage of Paridis Rhizoma promotes comprehensive utilization and development research of waste aerial parts of the original plant. The chemical compositions of the aerial parts of Paris polyphylla var. chinensis were clarified based on the ultrahigh performance liquid chromatography tandem quadrupoles time of flight mass spectrometry(UPLC-QTOF-MS/MS) in the previous investigation, and a series of flavonoids and steroidal saponins were isolated. The present study continued the isolation and structure identification of the new potential compounds discovered based on UPLC-QTOF-MS/MS. By using silica gel, ODS, flash rapid preparation, and other column chromatography techniques, combined with prepared high performance liquid chromatography, five compounds were isolated from the 75% ethanol extract of the aerial parts of P. polyphylla var. chinensis, and their structures were identified by spectral data combined with chemical transformations, respectively, as(23S,25R)-23,27-dihydroxy-diosgenin-3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranoside(1),(25R)-26-O-β-D-glucopyranosyl-furost-5-en-3β,22α,26-triol-3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside(2),(25R)-27-O-β-D-glucopyranosyl-5-en-3β,27-dihydroxyspirost-3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside(3),(25R)-27-O-β-D-glucopyranosyl-5-en-3β,27-dihydroxyspirost-3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranoside(4), and aculeatiside A(5). Among them, compounds 1-4 were new ones, and compound 5 was isolated from P. polyphylla var. chinensis for the first time.

Performance evaluation of a miniature LWMA MS designed for in situ lunar investigations

There is still no direct evidence for the existence of water ice and organic matter on the moon. The main goal of developing a miniature time-of-flight mass spectrometer (TOF MS), Lunar Water Molecular Analyzer Mass Spectrometer (LWMA MS), is to detect water ice, organic matter and other chemical components in situ on the moon. The miniature LWMA MS in this paper is composed of sampling introduction tube, gas charge tube, ion source, TOF mass analyzer and detector. The SIMION software was used to simulate the miniaturization design of the ion source and mass analyzer. Meanwhile, the developed miniature TOF MS was evaluated systematically. Its resolution is 151 for water and 163 for nitrogen, the mass range is from 1 to 500 amu, the stability of water is 3% during 12 h. Moreover, it was proved that the developed LWMA MS is able to detect water ice and organic matter through the experiments of the lunar soil simulant.

Functionalization of octaspherosilicate (HSiMe2O)8Si8O12 with buta-1,3-diynes by hydrosilylation

Hydrosilylation with octaspherosilicate (HSiMe2O)8Si8O12 (1) has provided hundreds of molecular and macromolecular systems so far, making this method the most popular in the synthesis of siloxane-based, nanometric, cubic, and reactive building blocks. However, there are no reports on its selective reaction with 1,3-diynes, which allows for the formation of new products with unique properties. Therefore, herein we present an efficient protocol for monohydrosilylation of symmetrically and non-symmetrically 1,4-disubstituted buta-1,3-diynes with 1. The compounds obtained bear double and triple bonds and other functionalities (e.g., Br, F, OH, SiR3), making them highly desirable, giant building blocks in organic synthesis and material chemistry. These compounds were fully characterized by 1H, 13C, 29Si, 1D NOE, 1H–13C HSQC NMR, FT–IR, and MALDI TOF MS, EA, UV–Vis, and TGA analysis. The TGA proved their high thermal stability up to 427 ℃ (Td10%) for compound 3j.

Nutritional, physicochemical and antioxidant properties of sprouted and fermented beverages made from Phalaris canariensis seed

SummaryThe development of fermented beverages from seeds is important because the fermentation process decreases the concentration of anti‐nutritional compounds, in addition, compounds that provide odour, flavour, and that have beneficial properties for the consumer are generated. The objective of this study was to evaluate the nutritional characteristics, physicochemical properties, antioxidants, volatile compounds, fatty acids and bioactive compounds of un‐sprouted canary seed, sprouted seed and a fermented beverage prepared from the germinated seed. The analysis of untargeted bioactive compounds by Ultra High‐Performance Liquid Chromatography coupled to a quadrupole time of flight mass spectrometer (UPLC‐MS‐QTOF) allowed the identification of the main metabolic pathways that occur during these processes. The sprouts contained linolenic acid, and the beverage contained fatty acids. L‐phenylalanine was the polyphenol present at the highest concentration in the seed, sprout and beverage. Seven volatile compounds were identified, of which 2‐methyl butanal and ethanol were found in the highest concentration in the sprouted and fermented seeds, respectively. The beverage exhibited the highest concentration of polyphenols and antioxidant activity assessed by the DPPH, FRAP and ABTS tests. We, therefore, conclude that the beverage could confer beneficial health effects, and the results provide information for the development of new functional canary seed products.

L-Arginine, as an essential amino acid, is a potential substitute for treating COPD via regulation of ROS/NLRP3/NF-κB signaling pathway.

Chronic obstructive pulmonary disease (COPD) is a frequent and common disease in clinical respiratory medicine and its mechanism is unclear. The purpose of this study was to find the new biomarkers of COPD and elucidate its role in the pathogenesis of COPD. Analysis of metabolites in plasma of COPD patients were performed by ultra-high performance liquid chromatography (UPLC) and quadrupole time-of-flight mass spectrometry (TOF-MS). The differential metabolites were analyzed and identified by multivariate analysis between COPD patients and healthy people. The role and mechanisms of the differential biomarkers in COPD were verified with COPD rats, arginosuccinate synthetase 1 (ASS-l) KO mice and bronchial epithelial cells (BECs). Meanwhile, whether the differential biomarkers can be the potential treatment targets for COPD was also investigated. 85 differentials metabolites were identified between COPD patients and healthy people by metabonomic. L-Arginine (LA) was the most obvious differential metabolite among the 85 metabolites. Compare with healthy people, the level of LA was markedly decreased in serum of COPD patients. It was found that LA had protective effects on COPD with in vivo and in vitro experiments. Silencing Ass-1, which regulates LA metabolism, and α-methy-DL-aspartic (NHLA), an Ass-1 inhibitor, canceled the protective effect of LA on COPD. The mechanism of LA in COPD was related to the inhibition of ROS/NLRP3/NF-κB signaling pathway. It was also found that exogenous LA significantly improved COPD via regulation of ROS/NLRP3/NF-κB signaling pathway. L-Arginine (LA) as a key metabolic marker is identified in COPD patients and has a protective effect on COPD via regulation of ROS/NLRP3/NF-κB signaling pathway. LA may be a novel target for the treatment of COPD and also a potential substitute for treating COPD.

Codium fragile Suppresses PM2.5-Induced Cognitive Dysfunction by Regulating Gut-Brain Axis via TLR-4/MyD88 Pathway.

This study was conducted to evaluate the cognitive dysfunction improvement effect of aqueous extract of Codium fragile (AECF) by regulating the imbalance of the gut-brain axis in chronic particulate matter (PM)2.5-exposed mice. The physiological compounds of AECF were identified as hexadecanamide, oleamide, octadecanamide, stearidonic acid, and linolenic acid by the ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC Q-TOF MSE) analysis. To evaluate the effect of PM2.5 on the antioxidant system, superoxide dismutase (SOD) contents, reduced glutathione (GSH) contents, and malondialdehyde (MDA) contents were measured in colon and brain tissues. AECF significantly ameliorated the imbalance of the antioxidant systems. Also, AECF improved intestinal myeloperoxidase (MPO) activity, the abundance of the gut microbiome, short-chain fatty acids (SCFAs) contents, and tight junction protein expression against PM2.5-induced damage. In addition, AECF prevented PM2.5-induced inflammatory and apoptotic expression via the toll-like receptor-4 (TLR-4)/myeloid differentiation primary response 88 (MyD88) pathway in colon and brain tissues. Additionally, AECF enhanced the mitochondrial function, including the mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) contents in brain tissues. Furthermore, AECF regulated the cholinergic system, such as acetylcholine (ACh) contents, acetylcholinesterase (AChE) activity, and protein expression levels of AChE and choline acetyltransferase (ChAT) in brain tissues. To evaluate the effect of cognitive dysfunction caused by PM2.5-induced intestinal dysfunction, behavior tests such as Y-maze, passive avoidance, and Morris water maze tests were performed. From the results of the behavior tests, AECF ameliorated spatial learning and memory, short-term memory, and long-term learning and memory function. This study confirmed that AECF reduced PM2.5-induced cognitive dysfunction by regulating gut microbiome and inflammation, apoptosis, and mitochondrial function by enhancing the gut-brain axis. Based on these results, this study suggests that AECF, which contains fatty acid amides, might be a potential material for ameliorating PM2.5-induced cognitive dysfunction via gut-brain axis improvement.

Synthesis of PDMS-μ-PCL Miktoarm Star Copolymers by Combinations (Є) of Styrenics-Assisted Atom Transfer Radical Coupling and Ring-Opening Polymerization and Study of the Self-Assembled Nanostructures.

Due to their diverse and unique physical properties, miktoarm star copolymers (μ-SCPs) have garnered significant attention. In our study, we employed α-monobomoisobutyryl-terminated polydimethylsiloxane (PDMS-Br) to carry out styrenics-assisted atom transfer radical coupling (SA ATRC) in the presence of 4-vinylbenzyl alcohol (VBA) at 0 °C. By achieving high coupling efficiency (χc = 0.95), we obtained mid-chain functionalized PDMS-VBAm-PDMS polymers with benzylic alcohols. Interestingly, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analysis revealed the insertion of only two VBA coupling agents (m = 2). Subsequently, the PDMS-VBA2-PDMS products underwent mid-chain extensions using ε-caprolactone (ε-CL) through ring-opening polymerization (ROP) with an efficient organo-catalyst at 40 °C, resulting in the synthesis of novel (PDMS)2-μ-(PCL)2 μ-SCPs. Eventually, novel (PDMS)2-μ-(PCL)2 μ-SCPs were obtained. The obtained PDMS-μ-PCL μ-SCPs were further subjected to examination of their solid-state self-assembly through small-angle X-ray scattering (SAXS) experiments. Notably, various nanostructures, including lamellae and hexagonally packed cylinders, were observed with a periodic size of approximately 15 nm. As a result, we successfully developed a simple and effective reaction combination (Є) strategy (i.e., SA ATRC-Є-ROP) for the synthesis of well-defined PDMS-μ-PCL μ-SCPs. This approach may open up new possibilities for fabricating nanostructures from siloxane-based materials.

Relationship between cancer stem cell-related SNPs and survival outcomes in patients with primary lung cancer

BackgroundCancer stem cells may be the source of cancer-causing mutant cells and are closely related to the prognosis of cancer. Our study aimed to investigate the potential association between single-nucleotide polymorphisms (SNPs) of cancer stem cell-related genes and the prognosis of lung cancer patients.MethodsThe SNP loci were genotyped by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF–MS), and the overall survival of subjects was analyzed by log-rank test after stratifying and adjusting their demographic data, clinical data, and genotypes. The correlation between survival time and quality of life of lung cancer under codominant, dominant, recessive, and additive genetic models was analyzed by the Cox regression model. The association between SNP polymorphism and the prognosis of lung cancer was analyzed by Stata16.0 software, and their heterogeneity was tested. Interaction analysis was performed using R software (version 4.2.0).ResultsStratified analysis unveiled that rs3740535 had recessive AA genotype and additive GG genotype; Rs3130932 dominant GT + GG genotype, additive TT genotype; Rs13409 additive TT genotype; Rs6815391 recessive CC genotype and additional TT genotype were associated with increased risk of lung cancer death. Rs3130932 recessive GG genotype was associated with a reduced risk of lung cancer death.ConclusionRs3740535, rs3130932, rs13409, and rs6815391 are associated with the overall survival of lung cancer patients and may be valuable for the prognosis of lung cancer patients.

Numerical analysis of pulsed extraction of ions from a 16-Pole / 16-Wire ion trap for time-of-flight mass spectrometry

Multipole radiofrequency ion traps are versatile tools for trapping and manipulating ions. The extraction of ions from such a trap leads to broad time-of-flight (ToF) distributions, which make it incompatible with ToF mass spectrometry. In this work, we conducted numerical simulations of biomolecular ions stored in 16-pole and 16-wire ion traps to analyze their extraction characteristics. We show that the ions extracted from a wire trap with a simple upgrade exhibit ToF distributions two orders of magnitude narrower than that typically results from conventional ion traps. Further, in the upgraded design, the ions can be confined within a much narrower region, which, together with higher optical access of the wire trap configuration, makes it compatible with fluorescence spectroscopy measurements.

Survey of bed bug infestations in homeless shelters in southern France

Bed bug has become a major public health pest worldwide. Infestation may result in numerous negative health effects. Homeless shelters are one of the most habitats that can be infested with bed bugs, a few studies have focused on bed bug infestations in these settings. We conducted a survey of infestations of bed bugs in a homeless shelter in southern France, using an innovative seven-level scale (0–6) to assess the degree of infestation, MALDI TOF-MS to identify bed bugs, and a biomolecular tool to detect bacteria. Bed bug infestations were documented in 13% (9/68) of investigated rooms. A total of 184 bed bugs were collected and morphologically identified as Cimex lectularius. MALDI TOF–MS analysis allowed us to obtain high-quality MS spectra for all 184 specimens, to correctly identify all specimens, and included 178/184 (97%) Log Score Values higher than 1.8. Among the bacteria tested, Wolbachia sp. DNA was found in 149/184 (81%) of the bed bugs, and one sample was positive for Coxiella burnetii, the agent of Q fever. Our study is the first of its kind that offers new perspectives for increasing public awareness of the conditions in homeless shelters.

Non-typhoidal salmonella contamination along the pork value chain in a rural East African setting: a cross-sectional study.

Non-typhoidal Salmonella (NTS) is a serious foodborne pathogen that has previously been isolated from pigs presented for slaughter in a rural pork value chain in western Kenya. To understand varying NTS contamination along the value chain we assessed prevalence at slaughter, transport and retail. Suspect isolates from culture were confirmed using matrix-assisted laser desorption-ionization time of flight mass spectrometry. Prevalence on pig carcasses, meat transportation containers, retailed raw and cooked pork and accompanying side salads was 18.1%, 23.9%, 28.0%, 1.9% and 8.6%, respectively. NTS contamination is propagated along the pork value chain in rural western Kenya, demonstrating the need for improved hygiene measures to prevent human exposure.

The BinDiscover database: a biology-focused meta-analysis tool for 156,000 GC–TOF MS metabolome samples

Metabolomics by gas chromatography/mass spectrometry (GC/MS) provides a standardized and reliable platform for understanding small molecule biology. Since 2005, the West Coast Metabolomics Center at the University of California at Davis has collated GC/MS metabolomics data from over 156,000 samples and 2000 studies into the standardized BinBase database. We believe that the observations from these samples will provide meaningful insight to biologists and that our data treatment and webtool will provide insight to others who seek to standardize disparate metabolomics studies. We here developed an easy-to-use query interface, BinDiscover, to enable intuitive, rapid hypothesis generation for biologists based on these metabolomic samples. BinDiscover creates observation summaries and graphics across a broad range of species, organs, diseases, and compounds. Throughout the components of BinDiscover, we emphasize the use of ontologies to aggregate large groups of samples based on the proximity of their metadata within these ontologies. This adjacency allows for the simultaneous exploration of entire categories such as “rodents”, “digestive tract”, or “amino acids”. The ontologies are particularly relevant for BinDiscover’s ontologically grouped differential analysis, which, like other components of BinDiscover, creates clear graphs and summary statistics across compounds and biological metadata. We exemplify BinDiscover’s extensive applicability in three showcases across biological domains.

Study on the water detection using the flowmeter method at low temperatures

To prepare for the lunar water exploration in the Chinese Lunar Exploration Project IV, a new apparatus for studying characteristics of the water vapor conductance and water detection at low temperatures was built based on the flowmeter method, and the performance of the miniature time-of-flight mass spectrometer (TOF-MS) for water detection in the range −20 to 20 °C was measured. The through-put within the range of 3 × 10−9–9 × 10−6 Pa m3 s−1 was provided at temperatures in the range −60 to 20 °C. The conductance of the orifice with a diameter of 21 µms for three gases (N2, Ar, and H2O) was measured at low temperatures. The diameter change of the metal orifice caused by the cold contraction in the molecular flow state is the main factor affecting the conductance, and the viscosity characteristic of gas in the viscous flow state is the main factor affecting the conductance. Therefore, the conductance of the orifice increases with the decreasing temperature when the through-put is high. In addition, the water vapor can be stably supplied by the orifice under low temperatures, and the conductance of water vapor through the orifice is measured through the on-line method and the time-ratio method. The adsorption rate and amount of water vapor on the metal surface increase with the decreasing temperature, hence the concentration of water molecules in the test dome significantly decreases as the temperature decreases. Finally, the through-put of water vapor of 8.75 × 10−8 Pa m3 s−1 was detected by the miniature TOF-MC at −20 °C on the apparatus.

Experimental and theoretical study on the photoionization of styrene.

This study employed a vacuum ultraviolet synchrotron radiation source and reflectron time-of-flight mass spectrometry (TOF-MS) to investigate the photoionization and dissociation of styrene. By analyzing the photoionization mass spectrum and efficiency curve alongside G3B3 theoretical calculations, we determined the ionization energy of the molecular ion, appearance energy of fragment ions, and relevant dissociation pathways. The major ion peaks observed in the photoionization mass spectra of styrene correspond to C8 H8 + , C8 H7 + and C6 H6 + . The ionization energy of styrene is measured as 8.46 ± 0.03 eV, whereas the appearance energies of C8 H7 + and C6 H6 + are found to be 12.42 ± 0.03 and 12.22 ± 0.03 eV, respectively, in agreement with theoretical values. The main channel for the photodissociation of styrene molecular ions is the formation of benzene ions, whereas the dissociation channel that loses hydrogen atoms is the secondary channel. Based on the experimental results and empirical formulas, the required dissociation energies (Ed ) of C8 H7 + , C8 H6 + and C6 H6 + are calculated to be (3.96 ± 0.06), (4.00 ± 0.06) and (3.76 ± 0.06) eV, respectively. Combined with related thermochemical parameters, the standard enthalpies of formations of C8 H8 + , C8 H7 + , C8 H6 + and C6 H6 + are determined to be 964.2, 1346.3, 1350.2 and 1327.0kJ/mol, respectively. Based on the theoretical study, the kinetic factors controlling the styrene dissociation reaction process are determined by using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. This provides a reference for further research on the atmospheric photooxidation reaction mechanism of styrene in atmospheric and interstellar environments.

Photophysical and photochemical studies on non-peripherally and peripherally Ga(III) chloro phthalocyanines in different solvents

Phthalocyanine compounds display strong absorbance during their interaction with light thanks to the delocalized π bonds. In recent years, the studies have been carried out to use phthalocyanine compounds, which are sensitive to light, as photosensitizers in the singlet oxygen production.In present work, two different phthalonitrile derivatives were separately obtained as a result of the reaction of 3-nitrophthalonitrile and 4-nitrophthalonitrile compounds with 2-hydroxymethyl-1,4-benzodioxane. As a result of the reaction of these phthalonitrile derivatives with gallium(III) metal ion, non-peripherally and peripherally 2-hydroxymethyl-1,4-benzodioxane substituted gallium(III) phthalocyanines (3-GaPc and 4-GaPc) were separately obtained. The synthesis of the compounds was performed by conventional methods and the characterization processes were carried out using ultraviolet and visible light (UV–vis) absorption spectroscopy, infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR ) spectroscopy and matrix assisted laser desorption/ionization mass spectroscopy (MALDI TOF MS) methods. Photophysical, photochemical and aggregation properties of two gallium(III) phthalocyanine compounds were investigated in different solvents such as dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and toluene solvents for their usability in singlet oxygen generation. Solvents have an effect on the results. The result show that these compound display good solubility and suitable singlet oxygen generation properties in the mentioned solvents.

Hierarchical hollow α-Fe2O3/ZnFe2O4/Mn2O3 Janus micromotors as dynamic and efficient microcleaners for enhanced photo-Fenton elimination of organic pollutants

Micro/nanomotors that can promote mass transport have attracted more and more research concern in the photocatalysis field. Here we first report a newly-designed hierarchical α-Fe2O3/ZnFe2O4/Mn2O3 magnetic micromotor as a heterogeneous photocatalyst for the degradation of cationic dye methylene blue (MB) from wastewater. The resulting three-dimensional (3D) flower-like hollow Janus micromotors are fabricated through a green and scalable strategy, in which each component has different functions. ZnFe2O4 microspheres serve as a magnetic scaffold for the nucleation and growth of α-Fe2O3 nanosheets and for the recycling of the micromachine. α-Fe2O3 nanosheets have shown great potential as an ideal semiconductor material for the photocatalytic decontamination of pollutants. Mn2O3 nanoparticles are mainly utilized as a catalyst to produce O2 bubbles to propel the autonomic movement of the micromotors in the presence of H2O2 fuel and also as a Fenton-like catalyst to decompose H2O2 to generate reactive oxygen species. Furthermore, the resultant micromotors exhibited linear-like motion form with an average speed of 189.1 μm s−1 in 5 wt% H2O2 solution. Moreover, the self-driven micromotors exhibited a superior catalytic degradation property toward MB, which was attributed to the synergistic effect of heterogeneous photocatalyst and the boosted micro-mixing and mass transfer caused by the vigorous motion of the micro-actuator. The possible degradation intermediates and passways of MB by α-Fe2O3/ZnFe2O4/Mn2O3 micromotor were identified with time of flight mass spectroscopy (TOF-MS). The 3D Janus micromotors have the potential to be used as a high-efficiency and active heterogeneous photocatalyst for the degradation of organic pollutants.