Separation of nicotine metabolites by capillary zone electrophoresis and capillary zone electrophoresis/mass spectrometry

The use of capillary zone electrophoresis (CZE) and capillary zone electrophoresis/mass spectrometry (CZE/MS) has been demonstrated, in principle, for the separation of nicotine and nicotine metabolites. The buffer system developed for separation and detection by CZE/UV was modified for use in CZE/MS analysis. Several of the metabolites are isobaric and tandem mass spectrometric (MS/MS) techniques have been used to differentiate such analytes.     

Alloys prepared by plasma-enhanced chemical vapor deposition (PECVD)

Three different techniques for the deposition of thin metal alloy films by plasma-enhanced chemical vapor deposition are described. These are the joint vaporization of a mixture of precursors, the use of separate sources connected directly to the reactor, and finally, the use of several reservoirs arranged in series. Various organometallics have been used as precursors to prepare combinations of Fe/Co and Au/Pt/Pd.     

Flow injection determination of ethanol in whole blood using immobilized enzymes

Enzymatic methods for the determination of ethanol in whole blood are proposed. They use different types of detection and flow injection analysis (FIA) modes: fluorometric detection (use of normal FIA and stopped-flow/FIA); amperometric detection by monitoring of NADH (use of normal amperometric and pulse mode) and with the aid of a coupled enzymatic reaction (2,6-dichlorophenolindophenol/diaphorase). Determination ranges between 0.1 and 30.0 μg/ml are obtained (which in all cases comprise the legal range of ethanol in blood), with good precision and sampling frequency. The sensitivity of the methods can be manipulated by changing the injected sample volume or the pH.     

离子色谱-抑制电导法分别测定海水中阴离子和阳离子

采用离子交换-抑制电导法测定海水中阴、阳离子。采用抑制电导可以降低淋洗液的背景电导,又可以增加被测离子的电导值,改善信噪比。采用的电化学自身再生抑制器,由连续电解水产生抑制淋洗液所需要的H^＋或者OH^-,加上电场引力,能用于高客量分离柱所用的淋洗液浓度和梯度淋洗。在试验条件下,利用阴离子和阳离子分离柱,配合抑制电导检测,可以同时分离和测定海水中7种阴离子和6种阳离子。且都可以得到很好的线性和较低的检出限。     

Laser spectroscopy in analytical chemistry:light on the next millennium

To date, lasers are widely accepted tools in analytical spectroscopy, involved in various stand-alone and hyphenated techniques. Furthermore, significant progress can be noted in this field. In this paper, first of all some laser characteristics are discussed. Subsequently, five selected topics are outlined to illustrate recent achievements and future developments:

1. Laser-induced fluorescence for detection in capillary electrophoresis, including the use of ultraviolet, continuous-wave lasers in combination with wavelength-resolved emission detection; the use of diode laser-induced fluorescence in the red region of the electromagnetic spectrum and the use of Ti:sapphire lasers for multiphoton-excited fluorescence detection.

2. Degenerate four-wave mixing for detection in liquid microseparation systems (based on the coherence of laser light).

3. Fluorescence line-narrowing spectroscopy for identification purposes, a cryogenic high-resolution molecular fluorescence technique with a high potential in environmental analysis.

4. Recent developments in Raman spectroscopy (including ultraviolet-Resonance Raman and hyphenation of liquid chromatography and Raman spectroscopy).

5. Use of lasers for sample introduction in inorganic analysis based on controlled material ablation.

A formal synthesis of (±) lycoramine via an intramolecular Heck reaction

The first use of an intramolecular Heck reaction for the construction of the quaternary centre of a galanthamine-like Amaryllidaceae alkaloid is described. The use of the acetate anion is shown as an activating factor in the 6-exo cyclisation of 5.     

化学改性碳在锂硫电池中的研究进展

自从我们课题组在2011年首次报道化学改性碳用于锂硫电池以来,其在锂硫电池中的应用便引起了人们的广泛关注。与传统碳质材料相比,化学改性碳在抑制多硫离子的溶解和扩散,实现锂硫电池长循环寿命方面展现出了其独特的优势和前景,已成为当前锂硫电池领域研究的热点和前沿。本综述主要报道了本课题组在化学改性碳高效利用硫材料以及其与多硫离子的化学和物理吸附协同作用高效固硫方面所取得的研究进展,系统介绍了不同化学改性碳的结构特点、优势及在锂硫电池中的应用,展望了化学改性碳在锂硫电池中的应用前景。     

Bakers' yeast oxidation of methyl para-tolylsuifide: Synthesis of a chiral intermediate in the preparation of the mevinic acid-type hypocholestemic agents

The use of (R)-methyl para-tolylsulfoxide as a chiral auxiliary in a novel synthesis of a key intermediate en route to mevinic acid-type hypocholestemic agents is described. The synthesis is short and simple consisting of eight steps to yield enantiomerically pure β-silyloxy-δ-lactone. The chiral sulfoxide used in the synthesis was obtained via a straightforward biooxidation of methyl para-tolylsulfide using bakers' yeast (Saccharomyces cerevisiae NCYC 73). The biotransformation involves the use of whole cells and affords the sulfoxide in good yield and with high stereoselectivity.     

Quantitative analysis of silicon- and aluminium-oxynitride films with EPMA, SIMS, hf-SNMS, hf-GD-OES and FT-IR

A precise and economic way for quantitative bulk analysis of silicon/aluminium, oxygen and nitrogen in the technological important silicon- and aluminium oxynitride thin films based on FT-IR and EPMA is presented and the use of data gained by the latter method is discussed for the calculation of relative sensitivity factors for SIMS and hf-SNMS. Advantages and disadvantages of SIMS, hf-SNMS and hf-GD-OES were compared. The combination FT-IR/EPMA/SIMS offers at present the best possibility for a quantitative bulk and in-depth distribution analysis of such films in the range of 20 to 1000 nm thickness. Alternatively for thicker films, combinations of FT-IR/EPMA/hf-SNMS or FT-IR/EPMA/hf-GD-OES are easier to apply but their use is restricted to oxygen concentrations higher than 10 wt%.     

On the determination of order parameters for homogeneous and twisted nematic liquid crystals from Raman spectroscopy

Traditional approaches to the use of Raman spectroscopy as an aid to the determination of local order parameters in liquid crystalline materials have employed polarizations of the excitation source and/or the analyser which are orthogonal to the liquid crystalline director. The present paper describes a Raman study, which seeks to take advantage of the additional information available from examining the complete range of orientations of the director in relation to these polarization directions. A theory is developed which shows how it is possible to use this additional information to derive more reliable values of the P₂ and P₄ local order parameters in homogeneous and twisted nematic liquid crystal cells.     

双催化剂对A-B2类反应的最优构象

在平面网格上将两个相邻格点定义为一个“超结构”，并在此基础上给出了一种新的元胞自动机模型用于模拟CO在α,β NMRD双催化剂表面的氧化反应.这里反应只在同一个超结构内发生，并以演化几率为参数，来控制超结构内反应物的反应过程.在模拟中，以平均反应速率最大对应的构象为最优构象,给出了以3×3网格为晶胞，α所占比例为1/9～8/9，及以4×4网格为晶胞α所占比例为1/16～15/16时的一系列α,β双催化剂的最优构象.     

IR, Raman and theoretical ab initio RHF study of aminoglutethimide — an anticancer drug

A comparative analysis of the IR and Raman spectra of aminoglutethimide (AG) dissolved in CCl₄, CHCl₃ and CH₃CN was performed. Most of the absorption bands were assigned to characteristic group vibrations with the use of the IR and Raman spectra of deuterated AG, glutethimide, N-methyl glutethimide and glutarimide. The AG samples very weakly interacting with the environment were studied with the use of the Ar matrix isolation IR spectra. For comparison, the IR and Raman spectra of the crystalline samples formed by hydrogen-bonded AG molecules were recorded. The spectra were analyzed also in terms of normal modes and the harmonic approximation with the use of the ab initio restricted Hartree-Fock theory. It was found that increasing the solute concentration in CCl₄ and CHCl₃ leads to formation of the autoassociates. In CH₃CN the solute–solvent AG–CH₃CN dimers occur. Possible structures of the associates were theoretically studied on the model systems: the centrosymmetric glutarimide dimer and the linear AG–CH₃CN dimer. By a comparison of the theoretical and experimental spectra we were able to identify several peaks originating from the solute–solvent interactions.     

Steroid-estrogen determination in sediment and sewage sludge: a critique of sample preparation and chromatographic/mass spectrometry considerations, incorporating a case study in method development

Steroid estrogens have been identified in the solid matrices of unit treatment processes in sewage treatment works (STWs) and in sediments of watercourses that receive effluent. This article discusses the sample preparation and analytical considerations necessary for reliable determination and the need to evaluate for possible matrix interferences during method development. Complementing this is a case study highlighting the potential for analyte transformation during sample preparation and the phenomena of ion suppression when utilising LC/MS ESI with a comparison of method recoveries by GC/MS. We discuss the use of LC/MS/MS and TOF instruments; however, at present, their use in environmental analyses appears to be limited because of their capital costs.     

示波极谱滴定的研究(ⅩⅩⅠ)——铂电极上的示波极谱滴定

本文研究了在微铂电极上进行示波极谱滴定的方法.有些地方,它比汞电极优越.这样大大地扩充了示波极谱滴定的应用范围.     

An Exciting Approach to Student Learning in Analytical Chemistry: It’s Jeopardy!

The television game show Jeopardy has been adapted for use in teaching students Quantitative Analysis. The exercise shows students how to study, encourages the development of good team-working skills, and presents the study of analytical chemistry in a fun and exciting way. One unique aspect of in this approach involves the use of data from the primary analytical literature as the basis for one category of problems called Real World. These questions help students see the significance and relevance of the material presented in the course for solving real-world problems and in their future careers. The approach can be used effectively in both large and small classrooms and can be adapted for use in other undergraduate chemistry courses, such as General Chemistry.