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The study of catalytic reaction mechanism is a critical and extremely challenging project. Online monitoring of reactants, intermediates and products during catalytic reactions can provide key evidence for the in-depth study of complex catalytic reaction networks, reaction pathways and reaction kinetics. As an online mass spectrometry based on soft ionization technique, vacuum ultraviolet photoionization mass spectrometry (VUV-PIMS) has proven itself as a versatile and powerful analytical technique for online and real-time process monitoring, which has gradually become a highly concerned characterization technique for catalytic reaction processes due to its advantages of high molecular ion yield, simple spectrum interpretation and high sensitivity. Compared with other commonly used synchrotron radiation and laser-based VUV light sources, the low pressure discharge lamps filled with various rare gases are compact, easy to operate, and low cost, such as krypton discharge lamps. However, the relatively low photon intensity of these lamps limits their applications. The efforts have been taken to develop stronger VUV light sources or lamp-based efficient combined ion sources to solve this issue. In this paper, the development of VUV-PIMS technology, especially the research progress of photoionization ion sources based on the VUV lamp, were reviewed, such as high-pressure photoionization (HPPI) source, single photon ionization-photoelectron ionization (SPI-PEI) combined ion source, and single photon ionization-chemical ionization (SPI-CI) combined ion source. By combining capillary sampling technology or molecular beam sampling technology, the applications of VUV-PIMS for real-time and online monitoring of stable products and active intermediates in catalytic processes were introduced, such as ammonia synthesis, methane/ethane catalytic conversion, methanol to olefins. The applications in online monitoring of these catalytic reaction processes exhibited an excellent performance and wide potential applications of VUV-PIMS in process monitoring and reaction mechanism research. Finally, the future development trend of VUV-PIMS was prospected for the application requirements of accurate characterization of catalytic reaction process.

Benzenes of wide sources can cause serious air pollution. In this study, a novel enrichment sampling device based on multi-capillary column was developed and coupled to portable photoionization time-of-flight mass spectrometer (PI-TOF-MS) to highly and sensitively detect benzenes in ambient air. The enrichment sampling device was composed of seven identical HP-PLOT Q capillary columns (0.10 m×0.53 mm×40 μm) coated with polystyrene-divinylbenzene, which could achieve efficient adsorption of benzenes at room temperature. The homebuilt portable PI-TOF-MS has a volume of (0.47×0.35×0.38) m3, a weight of 35 kg, and a resolution of better than 1 000 (full width at half-maximum, FWHM) at m/z 92. Benzene, toluene and p-xylene gas diluted by nitrogen were used to optimize the operating parameters of the whole system. The optimal sampling flow rate was selected as 500 mL/min, the enrichment time was 4 min, the thermal desorption temperature was 160 ℃, and the analytical time for single sample was less than 10 min. Compared with direct sampling, the signal intensities of benzene, toluene and p-xylene were enhanced by 130, 220 and 255 folds under the optimal conditions, respectively. The linearity, limit of quantitation (LOQ) and stability of the system were evaluated. As a result, the linear concentration range of 6.96-1 741.05 μg/m3 for benzene, 8.21-2 053.55 μg/m3 for toluene, and 9.46-2 366.05 μg/m3 for p-xylene were obtained with the correlation coefficients (R2) of 0.993 8, 0.999 7 and 0.999 1, respectively. The limits of quantification (LOQs, S/N=10) were 0.78, 0.63 and 0.76 μg/m3, respectively. The relative standard deviations of the signal strengths for the three compounds were less than 6% during seven analytical cycles. Finally, the developed multi-capillary column enrichment portable PI-TOF-MS was used for comparative analysis of indoor and outdoor air in the laboratory. As a consequence, toluene and p-xylene were detected in both indoor and outdoor air of the laboratory. The indoor concentrations of the two compounds were 2.6 and 23.3 μg/m3, respectively, which were much lower than the legal limit concentrations. Due to better ventilation, the outdoor concentrations of toluene and p-xylene were 0.5 and 16.4 μg/m3, respectively. In addition, ethanol, methanthiol, acetone, etc. were also detected in indoor air of the laboratory, which may come from human exhalations or chemical reagent emissions. The results showed that the instrument can meet the requirements of trace benzenes detection in ambient air, and has broad application prospects in the field of on-site environmental analysis.

Antibiotic misuse is becoming a worldwide public health issue due to serious risk to human health and environment. Residual antibiotics in environment mainly come from the wastewater from pharmaceutical factories, aquaculture, animal husbandry and hospitals. Antibiotics are included in the newly published List of Newly Controlled Pollutants (2022 Edition) (Draft for Comments). However, test standards are still lacking. Highly accurate results of the trace amounts of antibiotics distributed in the environment can be obtained by mass spectrometry coupled with chromatography. Nonetheless, sample pretreatment is time-consuming and expert-required. Compared with laboratory detection, ambient miniature mass spectrometry can realize on-site detection of the antibiotics without or with little pretreatment. On-site detection can be used for rapid qualitative and semi-quantitative detection, which can reflect the levels of water body pollution and accurately trace the pollutant sources. On-site detection also can provide technical support for the regulatory governance of antibiotics. But now no-studies have been reported on the on-site detection of environmental antibiotics in the field. It is urgent to develop a rapid detection method for antibiotic residues in the environment to assess antibiotic pollution and provide support for regulation. In this paper, the detection of antibiotics was carried out based on flash desorption and acetone assisted photoionization source miniature ion trap mass spectrometry, the detection parameters of antibiotics were systematically optimized including gas flow and injection time sequence, and a rapid and high throughput detection method of antibiotics was established. The efficiency of thermal desorption was improved using pulse purging mode and halogen lamp flash thermal desorption, and the signal intensities of high boiling point antibiotics were significantly increased. Quantitative detection of antibiotics was realized by isotope internal standard, and preliminary detection of antibiotics in water was carried out. This method does not need complicated pre-processing and can be completed in 1 min. The detection limits of isoniazid (INZ), ethionamide (ETN) and voriconazole (VCZ) were 636, 160, 35 μg/L, respectively, calculated based on S/N=3 at the injection volume of 1 μL. It is applicable to the field, high-throughput and highly sensitive detection of antibiotics.

Nano-clusters based materials have received increasing attention as smart materials owing to their unique optical, electronic properties, which make their promising for a wide range of applications, such as catalysis, sensors, and drug delivery, which will expand the science of clusters. A lot of efforts have been devoted to preparing nano-scale materials with controllable size and structure in order to achieve enhanced performances in certain applications. Mass spectrometry has been widely used for characterization of clusters with different m/z . Ion mobility spectrometry combined with mass spectrometry (IM-MS) is a new technique for characterization of mental nano-clusters, which can provide the information of both structure and m/z. In this review, we compared the advantages and disadvantages between IM-MS and single crystal diffraction, nuclear magnetic resonance spectroscopy, infrared spectroscopy. The principles of different IMS including travelling-wave ion mobility spectrometry, drift tube ion mobility spectrometry and differentia mobility spectrometry were introduced. Then, the structures of different commercial IM-MS were summarized and their applications for the characterization of nanocluster were introduced, which would help to expand the ion-chemistry of atomically precise clusters. The formation of ligated metal clusters through solution-phase chemical reduction is of interest due to their sizes and structures with tunable properties. Possible isomers in ligand protected Au and Ag cluster ions have been selectively detected and identified by ion mobility mass spectrometry. The structures for vanadium oxide cluster, chromium oxide cluster, nickel oxide cluster, cerium oxide cluster, titanium oxide cluster were investigated and confirmed based on the comparisons between the measured collision cross section and the theoretical simulation. Finally, the development tendency in future were discussed and prospected. Possible tendency was suggested as following: 1) IM-MS with higher resolution should be developed to measure the size and structure of metal clusters especially for isomers. 2) For the preparation of metal cluster with size and structure selected, the clusters with special property can be obtained through the combination of IM-MS with soft deposition device, the properties of such isomers and the insights they provide on the chemistry of monolayer-protected clusters would be subjects of a future study. 3) Comparing both experimental and theoretical collision cross section would aid in characterizing clusters and exploration of the dynamic equilibrium between isomer with different structures. 4) The relationship between the structure of metal cluster and the measured reduced mobility should be investigated and the corresponding fundamental database should be set up.

The dual emission (DE) characteristics of atomically precise copper nanoclusters (Cu NCs) are of significant theoretical and practical interest. Despite this, the underlying mechanism driving DE in Cu NCs remains elusive, primarily due to the complexities of excited state processes. Herein, a novel [Cu4(PPh3)4(C≡C−p−NH2C6H4)3]PF6 (Cu4) NC, shielded by alkynyl and exhibiting DE, was synthesized. Hydrostatic pressure was applied to Cu4, for the first time, to investigate the mechanism of DE. With increasing pressure, the higher‐energy emission peak of Cu4 gradually disappeared, leaving the lower‐energy emission peak as the dominant emission. Additionally, the Cu4 crystal exhibited notable piezochromism transitioning from cyan to orange. Angle‐dispersive synchrotron X‐ray diffraction results revealed that the reduced inter‐cluster distances under pressure brought the peripheral ligands closer, leading to the formation of new C−H⋅⋅⋅N and N−H⋅⋅⋅N hydrogen bonds in Cu4. It is proposed that these strengthened hydrogen bond interactions limit the ligands′ vibration, resulting in the vanishing of the higher‐energy peak. In situ high‐pressure Raman and vibrationally resolved emission spectra demonstrated that the benzene ring C=C stretching vibration is the structural source of the DE in Cu4. [ABSTRACT FROM AUTHOR]

The paper studies the geochronology and geochemistry of Qinjialing granodiorite and Hongqiling quartz diorite in Xiuyan-Fengcheng area, eastern Liaoning Province. The LA-ICP-MS zircon U-Pb dating yields the weighted average ages of 1 27.5±0.9 Ma for Qinjialing granodiorite and 1 26.5±0.8 Ma for Hongqiling quartz diorite, both of which were formed in the Early Cretaceous. The lithogeochemical analysis results show that the content of SiO2 in Qinjialling granodiorite is 70.40%-72.28%, with the A/CNK and ANK values of 0.99-1.06 and 1.44-1.61, respectively. The granodiorite is characterized by relatively enriched LREEs, depleted LILEs (Ba and Sr) and HFSEs (Nb, P and Ti), and enriched Rb, Th, La, Nd, and Hf, with the zircon saturation temperature ranging from 755 °C to 8 1 6 °C, belonging to peraluminous I-type granite, formed by the partial melting of lower crust. The content of SiO2 in Hongqiling quartz diorite is 56.42%-57.22%, with the ACNK and ANK values of 1.04-1.09 and 1.70-1.83, respectively. The quartz diorite is characterized by obvious negative Eu anomaly, depleted Sr, Nb, Ta, Ti and P, and enriched Ba, Rb, K, Zr, Hf and Th. The source material is derived from the crust with minors of mantle-derived component. The Qinjialing granodiorite and Hongqiling quartz diorite were formed in the Early Cretaceous extensional environment of eastern Liaoning, which are closely related to the destruction of North China Craton and lithospheric thinning. [ABSTRACT FROM AUTHOR]