Electrospray Ionization Mass Spectrometry (ESI-MS) as a Useful Tool for Fast Evaluation of Anion and Cation Complexation Abilities of a Cyclam Derivative

Electrospray ionization mass espectrometry (ESI-MS) has been used for the study of a cyclam derivative noncovalent interactions. At acidic pH, diprotonated macrocycle bound to different anionic species were observed. The selectivity shown by competitive experiments is rationalized with the help of semiempirical theoretical calculations. At basic pH, the base peak corresponded to the macrocycle-alkaline metal complexes, and again competition experiments showed different binding strength. Finally, experiments carried out in the presence of transition metal salts allowed the detection of the complexes present in the mixture and revealed their different kinetic behavior.     

Study of Nanocrystalline BiMnO3‐‐PbTiO3: Synthesis,Structural Elucidation,and Magnetic Characterization of the Whole Solid Solution

In the last ten years, the study and the search for new multiferroic materials have been a major challenge due to their potential applications in electronic technology. In this way, bismuth‐containing perovskites (BiMO₃), and particularly those in which the metal M position is occupied by a magnetically active cation, have been extensively investigated as possible multiferroic materials. From the point of view of synthesis, only a few of the possible bismuth‐containing perovskites can be prepared by conventional methods but at high pressures. Herein, the preparation of one of these potential multiferroic systems, the solid solution xBiMnO₃‐(1?x)PbTiO₃ by mechanosynthesis is reported. Note that this synthetic method allows the oxides with high x values, and more particularly the BiMnO₃ phase, to be obtained as nanocrystalline phases, in a single step and at room temperature without the application of external pressure. These results confirm that, in the case of Bi perovskites, mechanosynthesis is a good alternative to high‐pressure synthesis. These materials have been studied from the point of view of their structural characteristics by precession electron diffraction and magnetic property measurements.     

Online characterization of regulated and unregulated gaseous and particulate exhaust emissions from two-stroke mopeds: A chemometric approach

Two-stroke mopeds are a popular and convenient mean of transport in particular in the highly populated cities. These vehicles can emit potentially toxic gaseous and aerosol pollutants due to their engine technology. The legislative measurements of moped emissions are based on offline methods; however, the online characterization of gas and particulate phases offers great possibilities to understand aerosol formation mechanism and to adapt future emission standards. The purpose of this work was to study the emission behavior of two mopeds complying with different European emission standards (EURO-1 and EURO-2). A sophisticated set of online analyzers was applied to simultaneously monitor the gas phase and particulate phase of exhaust on a real time basis. The gaseous emission was analyzed with a high resolution Fourier transform infrared spectrometer (FTIR; nitrogen species) and a resonance-enhanced multiphoton ionization time-of-flight mass spectrometer (REMPI-ToF-MS; polycyclic aromatic hydrocarbons: PAH), whereas the particulate phase was chemically characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS; organic, nitrate and chloride aerosol) and a multiangle absorption photometer (MAAP; black carbon). The physical characterization of the aerosol was carried out with a condensation particle counter (CPC; particle number concentration) and a fast mobility particle sizer (FMPS; size distribution in real time). In order to extract underlying correlation between gas and solid emissions, principal component analysis was applied to the comprehensive online dataset. Multivariate analysis highlighted the considerable effect of the exhaust temperature on the particles and heavy PAH emissions. The results showed that the after-treatment used to comply with the latest EURO-2 emission standard may be responsible for the production of more potentially harmful particles compared to the EURO-1 moped emissions.     

Development of an automatic solid phase extraction and liquid chromatography mass spectrometry method by using a monolithic column for the analysis of Cyclosporin A in human plasma

A sensitive and specific and automated liquid chromatography-electrospray mass spectrometric (LC-ESI-MS) assay for the quantification of Cyclosporin A in human plasma was developed. Following a simple protein precipitation step, the supernatant was extracted on-line and directly injected into the system LC-ESI-MS. A relatively new type of monolithic column consisting of a silica rod with bimodal pore structure was used to achieve a retention time of 2.4 min with a very low backpressure at a flow rate of 1 ml/min. The assay was linear from 0.050 to 1.000 μg/ml. The mean recovery was 91%. The mean inter-day and intra-day precisions were 1.85% and 2.83%, respectively. The combination of the automated solid phase extraction and the low retention time achieved with this columns increase the throughput and decrease the time of analysis of each sample. This technology is useful in order to improve the efficiency of the bioanalytical studies.     

Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated.     

Simultaneous metabolic mapping of different anatomies by 1H HR-MAS chemical shift imaging

Analytical and Bioanalytical Chemistry - Localized information on a specimen is considered indispensable for deciphering biological activity. Magnetic resonance spectroscopy is a notable method...     

Improving the efficiency in the detection of gamma activities in environmental soil samples: influence of the granulometry and soil density

Ti(OH)₄ and TiCl₄ modified bentonite (Ti–Na-bent) were applied in the removal of Th(IV) from aqueous solution. Effect of different factors such as pH, contact time, temperature, initial concentration of Th(IV) and efficiency of them for thorium adsorption are investigated. Ti–Na-bent showed high adsorption capacity (q_m?=?231.37 mg/g) and quick adsorption kinetics at lower pH. The adsorption mechanisms involved are: (1) Th⁴⁺, [Th(OH)_4?n]ⁿ⁺ complexed on the outer-sphere of Na-bent and Ti–Na-bent. (2) Ion exchange between Th⁴⁺, [Th(OH)_4?n]ⁿ⁺ and exchangeable cations of Na-bent and the H on the hydroxyl group of Ti(OH)₄. Ti–Na-bent manifested high adsorption capacity for Th(IV), good acid resistance and long-term adsorption stability.