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Enabling liquid vapor analysis using synchrotron VUV single photon ionization mass spectrometry with a microfluidic interface
摘要： Vacuum ultraviolet (VUV) single photon ionization mass spectrometry (SPI-MS) is a vacuum-based technique typically used for the analysis of gas phase and solid samples, but not for liquids due to the challenge in introducing volatile liquids in a vacuum. Here we present the first demonstration of in situ liquid analysis by integrating the System for Analysis at the Liquid Vacuum Interface (SALVI) microfluidic reactor into VUV SPI-MS. Four representative volatile organic compound (VOC) solutions were used to illustrate the feasibility of liquid analysis. Our results show the accurate mass identification of the VOC molecules and the reliable determination of appearance energy that is consistent with ionization energy for gaseous species in the literature as reported. This work validates that the vacuum-compatible SALVI microfluidic interface can be utilized at the synchrotron beamline and enable the in situ study of gas-phase molecules evaporating off the surface of a liquid, which holds importance in the study of condensed matter chemistry.
关键词： SALVI,VUV single photon ionization mass spectrometry,microfluidic interface,liquid vapor analysis,volatile organic compounds
更新于2025-09-04 15:30:14
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Synthesis of TiO2/SiO2-B2O3 Ternary Nanocomposites: Influence of Interfacial Properties on their Photocatalytic Activities with High Resolution Mass Spectrometry Monitoring
摘要： An investigation on unusual interface properties of unprecedented ternary composites, formed by the inclusion of assorted proportions of B2O3 into TiO2/SiO2 structure, is conducted herein. The influences of B2O3 content and calcination temperature were evaluated. The precursor TiO2/SiO2 material was synthesized via a simple sol-gel procedure that was followed by B2O3 inclusion via maceration and calcination. The materials were fully characterized and their photocatalytic performance to degrade the Indigo Carmine dye investigated. The material prepared with a B/Ti molar ratio of 1 and at calcination temperature of 350 °C (B1-350) showed the best performance, with a superior photocatalytic activity than that of commercial TiO2. The presence of B2O3-TiO2-SiO2 interfaces in the structure of such material was of critical importance in producing a material with these attractive features. Finally, high resolution mass spectrometry monitoring allowed for the characterization of the main degradation products formed under these conditions.
关键词： high resolution mass spectrometry,degradation of Indigo Carmine,B2O3-TiO2-SiO2 ternary nanocomposites,photocatalytic activity,by-products characterization,structural defects
更新于2025-09-04 15:30:14
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A novel experimental approach for liver analysis in rats exposed to Bisphenol A by means of LC-mass spectrometry and infrared spectroscopy
摘要： An innovative complementary approach using a liquid chromatographic-mass spectrometer method and infrared spectroscopy is proposed for measuring internal biological exposure to dangerous chemical contaminants and for monitoring biochemical changes in target organs. The proposed methodologies were validated and applied in the case of rats exposed to low-doses of Bisphenol A (BPA). A liquid chromatographic method coupled to a tandem mass spectrometer was used in order to measure BPA concentration in rat livers. BPA was detected at different levels in all liver samples from BPA-treated rats, although the exposure dose was the same in all treated animals, and also from control rats, highlighting the difficulties in eliminating external uncontrolled exposure and the need for internal biological monitoring. Fourier Transform Infrared analysis was applied to detect structural changes occurring in several molecules (lipids, proteins, carbohydrates and nucleic acids) as well as the presence of specific metabolic processes. The spectroscopic analyses clearly demonstrated a different lipid composition more than an evident lipid accumulation and a glycogen accumulation decrease, revealing a metabolic disturbance in livers with a normal histological aspect. These results demonstrated the potential of an integrated approach based on mass spectrometry and infrared spectroscopy to evaluate at an early stage the hepatotoxic effect of BPA exposure in an animal model. This approach can be usefully exploited in all the investigations aimed to provide better information concerning the interrelationships between contaminant exposure, dose, and health effects.
关键词： Bisphenol A exposure,Metabolic disturbance,Rat liver,Mass spectrometry,Infrared spectroscopy
更新于2025-09-04 15:30:14
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Process Analytical Technology for Online Monitoring of Organic Reactions by Mass Spectrometry and UV–Vis Spectroscopy
摘要： Process analytical technologies (PATs) are used in the pharmaceutical and other industries to monitor chemical processes in real-time with analytical instrumentation. Each PAT analyzer brings its own advantages and disadvantages to the process, and multiplexing PAT analyzers can be advantageous as they can provide confirmatory measurements and increase the overall confidence of the analysis. In a pedagogical setting, online reaction monitoring enables the instructor to explain the fundamentals of instrumental techniques while highlighting pertinent real-world applications. Here we present a teaching laboratory exercise in which students monitor an amide bond formation reaction by flow UV?vis spectroscopy and by mass spectrometric analysis. The coupling of these two specific instruments allows students to investigate two instruments in one laboratory exercise, to explore the fundamentals behind each, and to contemplate the advantages and disadvantages of these instrumental methods. The coupling of the two instruments was aided by 3D printing which allowed students to explore how rapid prototyping can enable the development of innovative procedures.
关键词： Organic Chemistry,Mass Spectrometry,UV?Vis Spectroscopy,Laboratory Instruction,Instrumental Methods,Hands-On Learning/Manipulatives,Upper-Division Undergraduate,Analytical Chemistry,Reactions
更新于2025-09-04 15:30:14
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Preparation and characterization of a novel nanocomposite coating based on sol-gel titania/hydroxyapatite for solid-phase microextraction
摘要： In this work a novel nanocomposite coating with high thermal stability and high durability is prepared. The surface of the stainless steel as a support was initially modified by (3–mercaptopropyl)trimethoxysilane. Surface characteristics of pure titania (TiO2), pure hydroxyapatite (HAP) and Hap/TiO2 nanocomposite coating were investigated and compared by energy dispersive X–ray (EDX) spectroscopy as well as by field emission–scanning electron microscopy (FESEM). The mutual effects of components on each other were discussed. Addition of HAP sol to the pure TiO2 sol, considerably changes the coating morphology. The applicability of the sol–gel HAP/TiO2 fiber was assessed for the headspace solid–phase microextraction (HS–SPME) of benzene, toluene, ethylbenzene and xylenes (BTEXs) from water sample followed by gas chromatography–mass spectrometry (GC–MS). Important parameters affecting the extraction efficiency were investigated. The efficiency of HAP/TiO2 nanocomposite coating was compared with other reported fibers and showed very good results. Under optimal conditions, the detection limits (S/N = 3) were in the range of 0.04 to 1 μg L?1, and the limits of quantification (S/N = 10) were between 0.1 and 4 μg L?1. The relative standard deviations (RSDs) for each fiber (at 20 μg L?1 and n = 5) were in the range of 1.76 to 8.18%, while the RSDs between fibers were 3.03 to 10.02%. The method showed a large linearity in the range from 0.1 to 1000 μg L?1 with correlation coefficients of > 0.995.
关键词： Gas chromatography–mass spectrometry,BTEX,Hydroxyapatite,Solid-phase microextraction,Sol–gel technology,Titania
更新于2025-09-04 15:30:14