Abstract: Effective detection of metals in the environment and food is crucial to environmental protection and human health.Sample preparation is considered a key step in the whole analytical protocol since, besides being considered time-consuming, it is one of the most critical steps in terms of analyte losses and contaminations.Thus for improving the selectivity and sensitivity of metal analyte, extraction and clean-up steps are required.In this paper, the characteristics of new methods in metal ion pretreatment, such as cloud phase extraction, ionic liquids, dispersive liquid-liquid microextraction, headspace-solid phase microextraction, supercritical fluid extraction, and the advances in applications of which in the preparation of complex samples are summarized, and the direction for future development is proposed.
Abstract: Metal organic frameworks (MOFs) are an emerging class of organic-inorganic hybrid crystalline porous materials formed by the coordination bonds of metal ions or metal clusters with organic ligands.Owing to the advantages of large specific surface area, good thermal stability and chemical stability, diverse structures and functionality, the application of MOFs as the stationary phase of capillary electrochromatography (CEC) has attracted much attention in recent years.In this review, the recent advances in the application of MOFs in CEC, including the development of novel coating techniques and their application in separation field are summarized.The prospects of MOFs in CEC are also presented.
Abstract: Electronic sensing technology has been widely used in the field of traditional Chinese medicine and agricultural products in recent years because of its advantages such as easy access to signal, rich information and overall characterization of sample properties.In this paper, the commonly used electronic sensing technologies, such as electronic eye, electronic nose and electronic tongue, are introduced.The application reports of the above mentioned technologies in the fields of natural products, such as traditional Chinese medicine, tobacco, food and beverage, are reviewed.The related multivariate data analysis, multi-source data fusion technology, brand protection technology and future instrument research and development are prospected.The purpose is to provide reference for the application of electronic sensing technology in the field of natural products analysis.
Abstract: Roses have important ornamental and medicinal values.The main chemical components are rose essential oils, flavonoids, polysaccharides, phenolic acids, etc.Rose has the effects of myocardial protection, anti-oxidation, anti-bacterial, anti-tumor, anti-virus, sedative, hypnotic, regulating blood lipids, and lowering blood sugar.Rose essential oil is an irreplaceable raw material for high-quality perfumes, spices and cosmetics, and its extraction process is the focus of industrial research.In this article the chemical components and biological activities of roses was reviewed, and the extraction process, components and biological activities of rose essential oil was focused on, which provides a reference for the future research and development of rose, especially rose essential oil.
Abstract: Based on the on-line analysis of gas products and the construction of photocatalytic reaction system, a batch on-line chromatographic analysis with multiple reaction channels has been realized and the photocatalyst activity evaluation system is established.Through the connection with the experimental device, the on-line gas chromatographic analysis can detect the catalytic reaction product qualitatively and quantitatively in real time, improve the analysis efficiency and provide efficient, convenient and systematic services for scientific research work.At the same time, the established photocatalyst activity evaluation system can lay an experimental foundation for the research of photochemical conversion and use of solar energy and environmental protection technology.The device system has expanded the use function of the instrument, and with improved application scope, which provides reference for the research and development of chemical synthesis catalyst evaluation system.
Abstract: Photocatalysis is one of the most ideal technology to solve the energy and environmental problem, which could make use of sufficient solar energy to decompose water to H2, degrade various organic pollutants, and reduce CO2 to organic low-carbon fuel.The present infrared spectrometer can only be used to analyze the molecular structure of photocatalytic materials in a conventional manner, which cannot investigate the illumination process in real time, and cannot realize the real-time detection and characterization of the change of photocatalytic material and reaction mechanism during the illumination process.An in-situ infrared spectroscopic cell system for the photocatalytic materials has been designed to provide a real-time detection and characterization of catalytic materials during the illumination process, so as to analyze the reaction mechanism of in-situ infrared photocatalysis and realize the real-time detection and characterization of the reaction mechanism of photocatalytic materials.The system provides a strong technical support to study the real-time structure change of photocatalytic materials, and is a very important technical innovation for the functional development of infrared spectrometers.
Abstract: The alcohol-soluble substances were extracted with the ultrasonic extraction using ethanol as the solvent from Pu-erh tea 7542, used as the reference sample.The gas chromatographic-mass spectrometric (GC-MS) fingerprint of alcohol-soluble substances in Pu-erh tea has been established, and the similarity calculation and principal components were analyzed.The results showed that the optimal extraction method of alcohol-soluble substances in Pu-erh tea were as follows:50 mL 95% ethanol was used as the solvent and ultrasonically extracted for 30 min? the optimum headspace oscillator temperature was 110℃ with the oscillation duration for 20 min.The similarity of the volatile constituents GC-MS fingerprint of alcohol-soluble substances in Pu-erh tea and the reference fingerprint was between 0.706 and 0.906, which showed that the volatile constituents had slight differences in the 9 different ages and batches of Pu-erh teas, but the peak area percentages of the common components varied greatly.Through the principal component analysis of the common components of volatile components of the alcohol-soluble substances in 9 different ages and batches of Pu-erh tea 7542, two components, 2-hydroxymethyl-2-methyl-pyrrolidine-1-carbaldehyde and N-butylbenzene sulfonamide extracted.Their eigenvalue were greater than 1 and the contribution rate was 90.2%, which can better reflect the main volatile components in the alcohol solute of Pu-erh tea 7542 series.Therefore, the assay of 2-hydroxymethyl-2-methyl-pyrrolidine-1-carbaldehyde and N-butylbenzene sulfonamide can decide the quality of different ages and batches of Pu-erh teas.
Abstract: A method for the detection of γ-FeOOH in iron oxide desulfurizing agent has been established using X-ray diffraction analysis.The integral intensity of the quantitative diffraction peak of γ-FeOOH exhibited a good linear relationship with its percentage in the range of 30% to 100%.The linear correlation coefficient was 0.997 7, which provided a research idea for the determination of FeOOH content in different crystal types.A sample of γ-FeOOH desulfurizer with known content was also determined with a relative error of 3.7%.Using this method, the polymorphic mixture of FeOOH in the desulfurizer sample can be analyzed qualitatively and quantitatively, which is of great significance for the further study of the polymorphic mixture of FeOOH in the desulfurizer.The method is accurate, reliable, easy to operate and feasible to some extent.It provides a reference for the qualitative and quantitative analysis of γ-FeOOH in iron oxide desulfurizer.
Abstract: A method to determine residual solvent in Azanavir sulfate by gas chromatography (GC) has been set up.And the sample preparation method using methanol:n-butanol (1:1, V/V) as the diluent was clarified particularly to eliminate the problem of interference in the determination.Test conditions of the flame ionization detector (FID) were as follows:temperature:240℃, temperature of injection port:200℃, split ratio:20:1, carrier gas:N2, flow rate:1 mL/min.The initial temperature of the chromatographic column was 35℃, kept for 3 min, then increased to 70℃ at a heating rate of 2℃/min, and then increased to 220℃ at a heating rate of 20℃/min, and maintained for 2 min.The results showed that the interference problem of solvent mixture was solved, and the blank solution and Azanavir sulfate did not interfere the solvents to be tested, and all the residual solvent peaks were well separated, so the specificity was good.The LODs of ethanol, acetone, isopropanol, dichloromethane, methyl tert-butyl ether, n-heptane were 2.063, 0.575, 2.001, 4.379, 0.875, 0.504 μg/mL respectively.The linearities of above solvents were acceptable in the range of 5.16~751.23, 1.74~722.29, 5.00~754.03, 13.27~89.79, 2.65~750.12, 1.53~749.43 μg/mL (r=0.999 0~1.000 0) respectively.The RSD of the same homogenous sample was less than 5.0%, so the method was reproducible.The recoveries of all the results were in the range of 90%~110%, so the method was accurate.The method was suitable for testing residual solvents in Azanavir sulfate.