Capillary electrophoresis off-line matrix-assisted laser desorption/ionisation mass spectrometry of intact and digested proteins using cationic-coated capillaries

Capillary electrophoresis (CE) was coupled off-line with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the analysis of proteins and peptides. CE fractions were collected directly on a matrix-coated MALDI target, using a sheath-flow interface. Protein adsorption during CE separations was prevented by coating the capillaries with the physically adsorbed, cationic polymer PolyE-323. The CE/MALDI-MS system was used for the analysis of model proteins and peptides at physiological pH as well as analysis of proteins in tear fluid. Moreover, tryptic on-target digestion of the collected protein fractions, with subsequent MALDI-MS and MS/MS peptide analysis, was demonstrated.     

壳寡糖锌(Ⅱ)配合物的合成与结构表征

以壳寡糖(COS)为配位体,锌(Ⅱ)离子为配位离子,在均相反应条件下合成了壳寡糖锌(Ⅱ)配合物(COS-Zn),并优化了配合物的合成条件.利用红外光谱法(FT-IR)、差热分析法(DTA)和元素分析(EA)进行结构表征,并对配位机理进行了初步探讨.     

一种新型超临界流体萃取-高效液相色谱在线联用系统的构建

天然产物研究一直是植物学、化学和药学的重要研究领域．通过从天然产物中寻找生物活性成分和先导物是创制新药的有效途径之一．有效成分的提取是天然产物研究中最基本和最关键的环节．超临界流体萃取（Supercritical fluid extraction,简称SFE）是近年来发展较快的一种新型样品提取技术．超临界CO2作为最常用的萃取剂已被用于天然药物中非极性和弱极性有效成分的提取,尤其是挥发性和热敏性的物质．此外,通过加入适当的添加剂还可有效地萃取极性化合物,和传统的化学方法相比,     

Total-reflection X-ray fluorescence analysis of Austrian wine

The concentration of major, minor and trace elements in Austrian wine was determined by total-reflection X-ray fluorescence using gallium as internal standard. A multi-elemental analysis was possible by pipetting 6 μl of wine directly on the reflector and drying. Total-reflection X-ray fluorescence analysis was performed with Atomika EXTRA II A (Cameca) X-rays from a Mo tube with a high-energy cut-off at 20 keV in total-reflection geometry. The results showed that it was possible to identify only by the elemental analysis as fingerprint the vineyards and year of vintage among 11 different wines.     

Evaluation of different clean-up procedures for the analysis of heterocyclic aromatic amines in a lyophilized meat extract

Along with other mutagenic and carcinogenic contaminants in foods such as aflatoxins, and polycyclic aromatic hydrocarbons, heterocyclic aromatic amines (HAAs) have received considerable attention in recent years. A major drawback in the analysis of HAAs in foods is their very low level of concentration (0.1 50 ng g-1) as well as matrix interferences. Solid-phase extraction (SPE), forming an integral part of chromatographic analysis, is one of the procedures currently used for the extraction and purification of HAAs in food samples. In this paper a comparative study of several SPE procedures for HAAs determination was performed. Recoveries of the heterocyclic amines in the analysis of both a simple matrix such as a standard methanolic solution and a contaminated meat extract were established. HAAs were determined by HPLC analysis with photodiode-array detection (DAD) of the purified extracts, and the adequacy of different clean-up procedures for the analysis of a contaminated meat extract was discussed.     

Application of Ranging Analysis to the Quality Assessment of Wines on a Nominal Scale

This work is dedicated to wine quality assessment methods as a problem of considerable current interest. Well-known approaches to wine quality assessment are considered based on the concentrations of volatile substances in wines and on the results of their taste tests. Comparative analysis was carried out for the evaluation of wines on a nominal scale of quality (high, medium, low, and adulterated) by means of discriminant analysis. It was found that the classification of wines based on quality with the use of discriminant analysis as a ranging analysis method with consideration for the concentrations of volatile substances, which are responsible for their organoleptic properties, is highly competitive with their expert (tasting) evaluation. A mathematical model was constructed for the classification of wines into the above categories, and a program module was developed for the automation of calculations.     

Quantitative Analysis of Thin Aluminium-Oxynitride Films by EPMA

 Thin films of aluminium oxynitride with diverse composition were prepared by dc-magnetron sputtering of aluminium, utilising sputtering power as well as argon, oxygen and nitrogen gas flows to vary the composition. Since film properties depend mainly on the content of incorporated oxygen and nitrogen, a method for quantitative analysis of the main constituents based on electron probe micro analysis with energy dispersive detection was developed. The excellent precision of the quantitative results for aluminium as well as oxygen and nitrogen are shown. Furthermore, a film layer analysis program was applied for the quantification of several films deposited under the same deposition parameters on silicon wafers, from 520 nm down to 40 nm thickness, showing that electron probe micro analysis with energy dispersive detection is a reliable method for quantitative compositional analysis of thin aluminium oxynitride films down to approximately 20 nm thickness. Since this method of analysis provides only bulk information, expected inhomogeneities of the depth distribution of the film components were checked by secondary ion mass spectrometry depth profiles of two thin films and correlated to the EPMA results. The thickness of the films was determined by ellipsometry. Received September 1, 1998     

Fast CEC-MS using poly(dimethylsiloxane) microinjector, short packed column, and low-sheath-flow interface

A fast CEC-MS approach based on a microinjector and a short CEC column was developed. Poly(dimethylsiloxane) was used as the substrate for microinjector fabrication. A short capillary column (～5 cm) packed with 5 μm octadecyl silica particles was inserted into the microinjector. The microinjector CEC device was interfaced to ESI-MS using a low-flow sheath liquid interface. The device delivers the advantages of sample introduction, pre-concentration, elution, and fast analysis as in chip-CEC yet avoids the difficulty of packing stationary material into the chip. The online pre-concentration and CEC-MS analysis capabilities of this device were demonstrated by analysis of a six-triazine mixture. A signal enhancement of 20-99-fold was achieved with a sample loading time of 180 s.     

小檗碱质谱碎片离子稳定性分析及碎裂机理的量子化学研究

用量子化学B3LYP/6-31G(d)方法, 研究了小檗碱质谱碎片离子的稳定性规律. 通过几何参数分析、 结合能计算和前线分子轨道分析, 研究碎片离子可能的活性部位及各部位相对反应活性, 并从理论上探讨了质谱碎裂机理. 结合能计算结果表明, 分子离子中C9所连甲氧基的C—O键比C10所连甲氧基的C—O键更容易断裂. 同时发现, 质谱碎裂过程中, 氢的解离促进了羰基的解离, 即质谱中常见的解离CO的过程.     

A chemically modified carbon paste electrode with d-lactate dehydrogenase and alanine aminotranferase enzyme sequences for d-lactic acid analysis

An amperometric biosensor was constructed for the analysis of d-lactic acid based on immobilizing d-lactate dehydrogenase(d-LDH), alanine aminotransferase (ALT), NAD(+), a redox polymer and polyethylenimine in carbon paste. The effect of addition of ALT in the paste, using enzyme sequences of ALT/d-LDH, was insignificant for d-lactic acid analysis. The responses of d-lactic acid in ALT/d-LDH paste electrode are the same as those in d-LDH paste electrode. However, the interference effect of pyruvate in the sample can be substantially reduced if sodium glutamate was applied in the carrier solution. When ALT immobilized in control porous glass as an immobilized enzyme reactor (IMER) was mounted in flow injection analysis system with the d-LDH paste electrode as detector for d-lactate analysis, the interference of the pyruvate can be significantly eliminated. The adverse effect of pyruvate in the samples for d-lactic acid analysis was reduced more effectively in ALT IMER with d-LDH electrode than in ALT/d-LDH electrode.     

Whole blood analysis for medical diagnostics by GC-MS with Cold EI

This study covers a new method and related instrumentation for whole blood analysis for medical diagnostics. Two-μL whole blood samples were collected using “minimal invasive” diabetes lancet and placed on a thin glass rod mounted on a newly designed BloodProbe. The BloodProbe with the whole blood sample was inserted directly into a ChromatoProbe mounted on the GC inlet, and thus, no sample preparation was involved. The analysis was performed within 10 min using a GC-MS with Cold EI that is based on interfacing GC and MS with supersonic molecular beams (SMB) along with electron ionization of vibrationally cold sample compounds in the SMB (hence the name Cold EI). Our blood analysis revealed several observations: (1) Detailed mass chromatograms were generated with full range of all the nonpolar lipids in blood including fatty acids, cholesterol, cholesteryl esters, vitamin E, monoglycerides, diglycerides, and triglycerides. (2) The analysis of whole blood was found to be as informative as the conventional clinical analysis of blood serum. (3) Cholesteryl esters were more sensitive than free cholesterol alone to the effect of diet of obese people. (4) Major enhancement of several fatty acid methyl esters was found in the blood of a cancer patient with liver dysfunction. (5) Vitamin E as both α- and β-tocopherol was found with person-dependent ratio of these two compounds. (6) Elemental sulfur S₈ was identified in blood. (7) Several drugs and other compounds were found and need further study of their correlation to medical issues.     

Study on structure and characterization of inclusion complex of gossypol/beta cyclodextrin

The inclusion complex of beta-cyclodextrin with gossypol was synthesized by using a convenient method of microwave irradiation. The structure of the complex was determined by 1H NMR, IR spectroscopy, and as well as the elemental analysis; the thermal stability was studied by means of differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The association constant between gossypol and beta-cyclodextrin measured via UV spectroscopy was 4462M(-1) at room temperature, following stoichiometry 1:2.     

The mbth oxidative determination of olefinic compounds

Oxidation of olefinic compounds with a permanganate-periodate procedure followed by analysis with 3-methyl-2-benzothiazoline hydrazone gave a sensitive method for the assay of a wide variety of these types of compounds. The method was especially sensitive for compounds with a 1-ene group A large number of olefins and water-soluble compounds, such as unsaturated acids, alcohols, and amines were found to be capable of analysis by the method. The procedure was applied to the analysis of aliphatic and acid fractions of airborne and other particulates.     

Pulsed discharge in a hollow cathode with the detection of ions in a time-of-flight mass spectrometer: Analytical capabilities in the analysis of solid samples

The results of a study of a new analytical system that includes an ion source with a hollow-cathode pulsed gas discharge and a time-of-flight mass spectrometer are reported. It was found that such a system can be successfully used for the direct analysis of metal and dielectric solid samples. The results of the optimization of various ionizer parameters, such as the delay of an ejecting pulse with respect to a discharge pulse and the bias voltage of the anode-cathode pair, are given. It was proposed to use an additive of hydrogen as a reaction gas for a considerable decrease in the intensities of gas components in the mass spectrum, and the effectiveness of this approach was demonstrated. The possibility of the rapid and efficient direct analysis of solid samples with the use of a hollow-cathode pulsed glow discharge was demonstrated using an example of the analysis of high-purity copper samples and the glassy slag of molten lead.     

复杂样品近红外光谱定量分析模型的构建方法

针对复杂样品近红外光谱分析中校正集的设计问题, 探讨了标准样品参与复杂样品建模的可行性. 通过标准样品和复杂基质样品共同构建的偏最小二乘(PLS)模型, 考察了波段筛选和建模参数对预测结果的影响. 结果表明, 采用PLS方法建立定量模型时, 校正集样品性质应该尽量与预测集样品相似, 当样品的性质相差较大时, 适当增加校正集样品的差异性可使模型具有更强的预测能力. 同时, 波段优选对提高预测结果的准确性具有重要的意义.     

Fabrication of flexible conducting thin films of copper-MWCNT from multi-component aqueous suspension by electrodeposition

Flexible thin films of metal–carbon nanotube (CNT) with densely populated CNT morphology were fabricated by electrodeposition from an optimized copper bath. The substrate used for the present work is polyethylene film that was pre-deposited with electroless copper as a seed layer before CNT deposition. Optimum concentration of CNT was incorporated into copper bath and the electrodeposition was done at quiescent and agitation conditions. The bonding between the seed layer and the electrodeposited copper was good as revealed from adhesion test. Electrical as well as physical-mechanical property of the film was improved by CNT incorporation within the metal matrix. The topography and the texture of the metal–CNT deposit showed a well-refined structure as per scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM), and scanning probe microscope (SPM) analysis. The stability of the film was tested by cyclic voltammetric and stripping analysis under various applied conditions. Raman spectra and Fourier transfer infrared spectroscopic (FT-IR) analysis revealed the presence of CNT and the functionality of CNT within the copper matrix. Transmission electron microscope (TEM) analysis showed nucleation of copper on the surface of CNT walls.     

The structure and conformational behavior of sulfonium salt glycosidase inhibitors in solution: a combined quantum mechanical NMR approach

We present the conformational analysis of an inhibitor of alpha-mannosidase, based on a novel sulfonium salt structure (1) that mimics the mannosyl cation intermediate. Because of the number of possible isomeric structures for 1, as well as its complex molecular structure, traditional conformational analysis by NMR was not applicable. Instead, a single experimentally consistent structure was obtained from finite perturbation quantum mechanical calculations of the NMR J-couplings at the B3LYP/6-311G** level. Using a full relaxation matrix analysis, we showed that the quantum-predicted NMR structure was the only isomer that was consistent with the experimental NOE intensities. The results illustrate the potential for finite perturbation calculations to be useful in the analysis of complex charged molecules.     

高分子量聚对二氧环己酮改进聚DL-乳酸柔韧性的研究

为了提高DL-聚乳酸(PDLLA)的柔韧性,将10～20wt%不同比例的由本课题组自主合成的高分子量聚对二氧环己酮(PPDO)加入到PDLLA基体中,对共混物的微观两相形态、力学性能、热学性能和表面性质、降解性能等物化性质进行了研究.实验结果表明,PPDO加入后,在PDLLA/PPDO共混物的柔韧性得到显著提高的同时,共混物表面亲水性相应提高,降解速率也随之加快.     

SBA-15负载CeO2纳米晶的溶胶-凝胶一步合成

以P123为模板剂, 正硅酸乙酯和硝酸铈为前驱体, 通过溶胶-凝胶路线在酸性条件下合成了SBA-15负载氧化铈(CeO2与SiO2质量比为28.7%)有序介孔材料. 采用热重/差热分析(TGA/DTA)、X射线衍射(XRD)、透射电镜(TEM)和氮气吸附等手段对所合成材料进行了表征. 结果表明, 合成的材料具有类似于SBA-15的结构, 孔径、孔容和比表面积分别为38.7 Å, 0.46 cm3/g和570 m2/g. X射线衍射(XRD)、透射电镜(TEM)、X射线能谱(EDS)和选区电子衍射花样联合表征证实了铈物种以高分散的CeO2纳米晶的形式分布在介孔基体中.     

Study of Pt-Re/alumina reforming catalysts by neutron activation analysis

The elemental analysis of Pt-Re/alumina catalysts was carried out by nondestructive and bulk neutron activation analysis. Samples were irradiated with a²⁴¹Am-Be source-based as well as accelerator-based thermal neutrons and induced activities were measured by a HPGe detector with a PC-based data acquisition and analysis system. An appropriate calibration technique was established for the determination of the respective ratios of each element present in the catalysts. The technique proved to be useful for the determination of low concentrations of Pt and Re in the catalyst samples.