Research Progress and Application of Ion Funnel Technique

Ion funnel is a new-style ion guider which can reduce spatial divergence and energy dispersity of the transmission ions by using radio frequency (RF) electric field to confine the ions radially and the direct current (DC) axial electric field to move the ions toward the exit, and thus it can greatly increase the ion transmission efficiency and improve the sensitivity of the mass spectrometry. Since ion funnel was invented in 1997, it has attracted a close attention of mass spectrometry scientists all over the world. Ion funnel has been used in various kinds of mass spectrometry, and built a bridge with high efficiency ion transmission between low vacuum ionization source and high vacuum mass analyzer. In this paper, the principle, technology development, and application progress of ion funnel are reviewed, and the future prospects are prospected.     

“聚丙烯酸酯的合成及降凝性能评价”综合实验能力考核平台

设计了以柴油中饱和烃含量及碳数分布测定、聚丙烯酸高级醇酯（PTA）的合成与纯化、PTA的红外表征与分子量测定、PTA降凝性能评价等4个模块组成的综合实验，作为化工专业实验的考核及成绩评定平台。这种考核方式将过程考核与结果考核融合，将笔试、操作、设计融合，可以全面准确地考核学生的有机合成、仪器分析等基础实验技能，同时考核综述、数据处理、实验设计等综合实验能力和实验室工作素质。此外，还能够有效训练学生的学习能力、解决问题能力、实践能力和创新能力，并促进了实验教学水平提高。     

A Methodology for Estimating Kinetic Parameters and Reactivity Ratios of Multi‐site Type Catalysts Using Polymerization,Fractionation, and Spectroscopic Techniques

This work describes a polymer reaction engineering framework for understanding how catalyst kinetic parameters affect the microstructure of polyolefins made with single‐ or multi‐site catalysts. Moreover, a methodology for deconvolution and kinetic parameters estimation is presented to estimate the reactivity ratios of multi‐site catalysts based on the combination of polymerization, fractionation, and spectroscopic techniques, namely, gel permeation chromatography‐IR and carbon‐13 nuclear magnetic resonance spectroscopy. The methodology capabilities are then demonstrated and validated using a case study simulated via a Monte Carlo model including random noise in order to better represent experimental result uncertainties. The methodology can reverse engineer experimental results and estimate all relevant reaction performance parameters.     

Proton conductivity study on three CS/IL@fle-MOF membranes

The low-cost, high specific surface area and porosity, controlled pore size, and chemical properties of metal–organic framework (MOF) materials have attracted much attention in the exploration of proton conduction. The method of chemically modifying MOF structures or introducing conductive medium into the holes can effectively improve the proton conductivities of the materials. Here, the structural tunability of ionic liquid (IL) and flexible MOF (fle-MOF) materials are matched to give full play to the conductivity of IL, the framework support, and the microporous effect of MOFs, which achieves the synergistic effect of performance and expands the temperature range of proton transfer. Three kinds of CS/IL@fle-MOF membranes were prepared by combining three fle-MOFs with 1-carboxymethyl-3-methylimidazole (CMMIM) in different proportions to obtain 15 pieces of membranes. The comparative analyses show that CS/IL@fle-MOF membranes have excellent proton conduction performance at a wider temperature range (263–353 K) and lower relative humidity (75% RH). Among them, the proton conductivities of CS/CMMIM@MIL-88A-25% and CS/CMMIM@MIL-88B-125% are up to 1.33 and 1.42 S cm⁻¹ at 75% RH and 353 K, respectively; whereas those of CS/CMMIM@MIL-53(Fe)-75% and CS/CMMIM@MIL-88B-125% reach up to 2.1 × 10⁻³ and 1.28 × 10⁻³ S cm⁻¹ at 75% RH and 263 K, respectively. The E_a of CS/CMMIM@fle-MOFs is in the range of 0.1–0.5 eV, suggesting that the proton transport follows predominantly the typical Grotthuss transfer mechanism. The results of this study indicate that the CS/CMMIM@fle-MOF membranes combinations offer great potential for the design of composite porous proton-conducting materials.     

Determination of sugars and cyclitols isolated from various morphological parts of Medicago sativa L

Plant research interest has increased all over the world, and a large body of evidence has been collected to show the huge potential of medicinal plants in various disease treatments. Medicago sativa L., known as alfalfa, is a rich source of biologically active components and secondary metabolites and was frequently used from the ancient times both as fodder crop and as a traditional medicine in the treatment of various diseases. Cyclitols, naturally occurring in this plant, have a particular interest for us due to their significant anti‐diabetic, antioxidant, anti‐inflammatory, and anti‐cancer properties. In the present study we revealed the isolation, the identification, and the quantification of some cyclitols and sugars extracted from different morphological parts of alfalfa plant. Soxhlet extraction and solid phase extraction were used as extraction and purification methods, while for the analyses derivatization followed by gas chromatography with mass spectrometry was involved. The obtained results showed significant differences in the quantities of cyclitols and sugars found in the investigated morphological parts, ranging between 0.02 and 13.86 mg/g of plant in case of cyclitols, and in the range of 0.09 and 40.09 mg/g of plant for sugars. However, roots have the richest part of cyclitols and sugars in contrast to the leaves.     

Analysis of thyreostats in bovine feces using ultra high performance liquid chromatography with tandem mass spectrometry

A method based on ultra‐high performance liquid chromatography was developed and validated to detect six thyreostatic compounds: tapazole, thiouracil, methylthiouracil, dimethylthiouracil, propylthiouracil, and phenylthiouracil in faeces of bovine. Thyreostats were extracted from the matrix with a mixture of methanol and buffer (pH = 8). Next step was derivatization of analytes with 3‐iodobenzylbromide. The liquid chromatographic separation of derivatives was obtained on a SB‐C18 column (50 × 2.1 mm; 1.8 μm, Agilent) with gradient elution using a mobile phase consisting of acetonitrile/0.1% acetic acid within 7.5 min. The analysis was performed on a Shimadzu NEXERA X2 ultra‐high performance liquid chromatograph with triple quadrupole MS 8050 instrument operating in positive electrospray ionization mode. Depending on the target compound, two or three diagnostic signals (selected reaction monitoring transitions) were monitored. The procedure was validated according to the Commission Decision 2002/657/EC. Recovery and repeatability met the performance criteria specified by this document for banned compounds. The recovery ranged from 97.5 to 110.5%, and repeatability did not exceed 14.1%. Decision limits and detection capabilities were below 10 μg/kg. The highest decision limits and detection capabilities concentrations were observed for phenylthiouracil of 3.48 and 6.96 μg/kg, respectively.     

常压下玉米秸秆液化工艺的优化及其生物油分析

随着化石能源的日益短缺，可再生木质生物质资源的利用越来越受到重视，常压液化技术是生物质资源高效利用的主要方式之一。利用单因素方法，探讨液化温度、复配液化剂二甘醇（DEG）与1,2-丙二醇（PG）的混合比、液固比、催化剂磷酸的用量、反应时间等因素对玉米秸秆液化得率的影响，以便优化其液化工艺；然后采用热重分析仪（TGA）、气相色谱-质谱技术（GC-MS）和核磁共振（NMR）技术对此优化条件下所得生物油的挥发降解特性和主要组成成分进行了检测探讨。分析表明，玉米秸秆液化时优化工艺参数为：液化温度170 ℃，液化剂DEG与PG混合比1∶2，液固比5∶1，H₃PO₄用量10%，反应时间45 min；此时玉米秸秆液化得率高至99.50%。TGA结果表明，此条件下所得生物油含有80%以上碳数小于25的化合物，热解后最终残炭量约为15%。GC-MS表明，可以检测出此生物油中含有的39种有机物，其中，醇类有机物的含量最多，酚类有机物的含量次之，它们相对含量依次是70.70%和25.63%，其还含有一定量的有机酸（2.80%）、醚类（0.64%）、酯类（0.10%）和酮类（0.13%）等有机物；其组分十分复杂，高含氧量，稳定性较差。1H-和13C-NMR分析表明，不同化学位移δ与生物油中不同类型的质子和碳原子相对应，明确生物油中不同类型H和C的分布，有利于对其分子结构进行深入探讨。这些研究为非木材生物质高效液化条件的选择及液化产物制备化学品和生物燃油给予理论基础与应用支持，促进了生物质资源的有效转化利用及其生物质基产品的开发。     

Van't Hoff analysis in chiral chromatography

The present review discusses the theory and application of van't Hoff analysis in chiral chromatography, with main focus on liquid chromatography. The topics considered include the physical meaning of van't Hoff equation's parameters, interpretation of thermodynamic data in terms of retention and enantioseparation mechanisms, abnormal behavior of van't Hoff plots, and best practices to avoid biased results.     

树状大分子接枝型聚合物色谱分离材料研究进展

随着色谱固定相制备技术和材料科学领域的不断发展,目前已经有大量修饰方法和新型材料被用于固相萃取、高效液相色谱以及离子色谱聚合物固定相填料的功能化修饰。其中聚酰胺-胺(PAMAM)树状大分子由于其独特的结构和性质,在色谱分离材料结构完善和性能提升中也发挥了重要的作用。该文主要综述了PAMAM树状大分子在以聚合物为基质的色谱分离材料修饰中的应用,并对其今后的发展进行了展望。     

Mass spectrometry imaging of latent fingerprints using titanium oxide development powder as an existing matrix

Recent research has focused on increasing the evidentiary value of latent fingerprints through chemical analysis. Although researchers have optimized the use of organic and metal matrices for matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) of latent fingerprints, the use of development powders as matrices has not been fully investigated. Carbon forensic powder (CFP), a common nonporous development technique, was shown to be an efficient one‐step matrix; however, a high‐resolution mass spectrometer was required in the low mass range due to carbon clusters. Titanium oxide (TiO₂) is another commonly used development powder, especially for dark nonporous surfaces. Here, forensic TiO₂ powder is utilized as a single‐step development and matrix technique for chemical imaging of latent fingerprints without the requirement of a high‐resolution mass spectrometer. All studied compounds were successfully detected when TiO₂ was used as the matrix in positive mode, although, generally, the overall ion signals were lower than the previously studied CFP. TiO₂ provided quality mass spectrometry (MS) images of endogenous and exogenous latent fingerprint compounds. The subsequent addition of traditional matrices on top of the TiO₂ powder was ineffective for universal detection of latent fingerprint compounds. Forensic TiO₂ development powder works as an efficient single‐step development and matrix technique for MALDI‐MSI analysis of latent fingerprints in positive mode and does not require a high‐resolution mass spectrometer for analysis.