Simultaneous extraction of organotin, organolead and organomercury species from soils and litter

Extracting organotin compounds (OTC) from soils is difficult due to the high cation exchange and complexation capacity of soils, and little information about OTC in soils is available. In this study, a new extraction method, combining 1 M CaCl₂, 0.1% tropolone, and glacial acetic acid was developed. Recoveries of mono-substituted OTC from spiked plant litter, and soil samples were improved substantially to 40% compared to classical glacial acetic acid extraction commonly used in sedimentology, yielding <10% recovery in C-rich soil samples. Simultaneously, the recovery of other OTC, trimethyllead and monomethylmercury was satisfactory. The recoveries of most species from the spiked litter, upland and wetland soils exceeded 70%. The new method extracted much more organometallics from unspiked organic soils and litter than microwave- and ultrasound-assisted extraction and accelerated solvent extraction, most likely due to exchange of organometallics from the solid phase by Ca²⁺. The method is simple, highly efficient and with low contamination. Together with GC-ICP-mass spectrometry, the method allows the detection of these organometallics in the pg g⁻¹ range and it is particularly suitable for soil and plant materials with low organometallics contents.     

Optimization of the Microwave-Assisted Saponification and Extraction of Organic Pollutants from Marine Biota Using Experimental Design and Artificial Neural Networks

Several improvements in sample pretreatment for the determination of organic pollutants (i.e. n-alkanes, polycyclic aromatic hydrocarbons, PAHs) in marine biota (mussels) are presented. The use of liquid nitrogen and homogenization of the samples are shown to be an alternative to the time consuming liophilization step required for the analysis of biota samples. Microwave-assisted hydrolysis and extraction are combined to isolate organic pollutants (19 n-alkanes and 27 PAHs) from biota matrices. Experimental design (ED) and artificial neural networks (ANNs) were used to optimize the experimental conditions. NIST-CRM 2978 was used to test the validity of the developed method which shows a good agreement with certified values.     

Analysis of organic acids in wines by Fourier-transform infrared spectroscopy

Fourier-transform infrared (FTIR) spectroscopy has been a major point of development in many wine laboratories in recent years. It enables almost instant analysis of several properties of wine, usually with very good precision and accurate results. Nevertheless, validation procedures should not be forgotten and should be fully performed. Recovery experiments were performed by spiking wine samples with different amounts of organic acids (tartaric, malic, lactic, acetic and citric—the most prominent in wines). After FTIR analysis of the total acidity and of each organic acid concentration, recoveries were calculated. For total acidity recovery results were, in general, good and very close to 100% (64–111%). On the other hand, for individual organic acid concentrations, the recovery results were lower than 100% (11–73%) for all spiking additions. These results could be explained by spectroscopic interferences between the organic acids. Because they have similar infrared spectra, it is not easy to distinguish between them and, therefore, to achieve accurate calibration. When total acidity, with a different infrared spectrum from the other abundant compounds in the wine, was taken as a single property the recovery results were acceptable.     

Organic acid solutions in the chromatography of inorganic ions VIII. Cation-exchange of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media

Summary The cation-exchange behaviour of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media at various concentrations and pH, was studied with Dowex 50 WX8 resin (200–400 mesh) in the ammonium form. Separation of Fe(III)/Cu(II), Fe(III)/Cu(II)/Zn(II), Fe(III)/Co(II)/Mn(II), Cu(II)/Ni(II)/Mn(II), Fe(III)/Cu(II)/Co(II)/Mn(II), Fe(III)/Cu(II)/Ni(II)/Cd(II), Yb(III)/Eu(III), Sc(III)/Y(III),Sc(III)/Yb(III)/Dy(III) and Nb(V)/Yb(III)/Ho(III) has been achieved, among others.This work was supported by C.N.R. of Italy.     

Robust interface on ENR-50/TiO2 nanohybrid material based sol-gel technique: Insights into synthesis,characterization and applications in optical

In this work, the sol–gel technique was used to prepare a new organic–inorganic hybrid from Epoxidized Natural Rubber (ENR-50) and Titanium dioxide (TiO₂) by blending different content of titania precursors (10, 30, and 50 wt%) with an ENR-50 matrix. A wide range of analyses was conducted to understand the nature of this hybrid and also to evaluate its potential uses in applications required high refractive index such as micro optical and optoelectronic devices. Results indicated that the ring-opening reaction of epoxide groups in ENR-50 increased with the increase of titania content in the hybrid resulting a strong bonding between titania and ENR-50 through TiOC bond, which was observed in FTIR spectrum at 1027–1028 cm⁻¹. It is also observed a slight decrease in the intensity of the amorphous peak along with a new crystalline peak appeared at 2θ = 23 and 27° due to the crystalline nature of titania. The hybrids showed three thermal degradation steps in the range of temperature 76 to 769 °C due to the existence of the Ti moieties with the mixture of polymer chains, which in turn shifted the T_g at 24.3, 26.9 and 28.1 °C for the hybrid at 10, 30, and 50 wt% TiO₂ compared to the T_g of ENR-50 at −18.4 °C respectively. The morphology of the ENR-50 showed clear changes during of the synthesis of ENR-50/TiO₂ hybrids, these changes were proven by SEM, TEM, and AFM analyses. Uv–Vis results showed that the higher wavelength peak at 293 nm has shifted to 296, 298 and 300 nm for the hybrid at 10, 30, and 50 wt% TiO₂ respectively due to the strong interaction between titania precursors and ENR-50 matrix. Furthermore, the hybrids showed good optical transparency in the visible light range.     

速差动力学分析及其应用进展

速差动力学分析是不经分离同时或连续测定混合物中性质密切相关的多组份的重要方法。本文综述了该法在１９８９－１９９２年间国内外新进展，尤着重其在有机，生物混合物中多组份分析的应用及新的计算方法，化学计量学的引入。引用最新文献６７篇。     

Electroabsorption study of metal-to-ligand charge transfer in an organic complex of iridium (III)

The dipole moment and polarizability changes have been determined from electroabsorption (EA) spectroscopy of solid films of fac tris(2-(phenyl)pyridinato,N,C^2′)iridium (III) [Ir(ppy)₃]. The maximum changes in the dipole moment |Δμ|_S=(5.0±0.5) D/f (f is the local field correction factor: 1.3–1.7) accompany ground state to the lowest singlet, and |Δμ|_T=(1.7±0.5) D/f ground state to the lowest triplet metal-to-ligand charge transfer (MLCT) excited states formation, while the average polarizability change ų/f² follows from the fitting procedure throughout the visible absorption spectrum range. The experimental values of |Δμ| as well as energy positions of the MLCT states correlate with the literature results of time-dependent density functional theory.     

“双一流”背景下高等农业院校有机化学基础课程教学新模式的构建及实践

The crop science of Sichuan Agricultural University is an authorized first-class discipline. As the strategic supporting department for innovative talent cultivation in agriculture and forestry major, we are facing a long-term challenge in reforming the teaching mode for basic course-organic chemistry and cultivating talented students with solid basic knowledge and strong sense of innovation. Herein a thorough survey was performing to establish the executable teaching programs for this course during the "Double-First Class Universities Plan" period. A multidimensional teaching resource library for organic chemistry course was also constructed. The new classroom teaching mode "Interest cultivation-Creative thought development-Autonomous and Cooperative learning", along with a stepwise practice teaching mode "Foundation skills-Integrated application-Innovative trial" was proposed and practiced among thirty-five majors including agriculture, forestry and veterinary, to improve the quality for innovative talent cultivation and support our first-class discipline construction. This research could probably serve as a reference for congeneric agricultural university.     

“线上线下-虚实结合”在有机化学实验教学中的应用探索——以正溴丁烷的制备实验为例

In response to the impact of the Covid-19 epidemic on organic chemistry laboratory teaching, this article analyzes and discusses the current limitation of traditional organic chemistry laboratory teaching. Taking the "preparation of n-bromobutane" as an example, a new "online-offline and virtual-actual combination" teaching mode with the combination of "Tencent Meeting, MLabs, laboratory and WeChat group" is introduced. The practice of the new mode of teaching includes the following steps: pre-class online guiding by teacher, student preview and practice based on the virtual simulation platform, students and teacher discussion and operation in laboratory, and post-classcomprehensive assessment and Q&A", and good teaching effects have been received. It is significant in cultivating and improving the independent innovation and practical ability, and provides reference for the organic chemistry laboratory teaching reform and also lays a foundation for the construction of "outstanding course" of organic chemistry.