Fabrication of a glass-implemented microcapillary electrophoresis device with integrated contactless conductivity detection

Glass microdevices for capillary electrophoresis (CE) gained a lot of interest in the development of micrototal analysis systems (microTAS). The fabrication of a microTAS requires integration of sampling, chemical separation and detection systems into a microdevice. The integration of a detection system into a microchannel, however, is hampered by the lack of suitable microfabrication technology. Here, a microfabrication method for integration of insulated microelectrodes inside a leakage-free microchannel in glass is presented. A combination of newly developed technological approaches, such as low-temperature glass-to-glass anodic bonding, channel etching, fabrication of buried metal interconnects, and deposition of thin plasma-enhanced chemical vapour deposition (PECVD) silicon carbide layers, enables the fabrication of a CE microdevice with an integrated contactless conductivity detector. The fabrication method of this CE microdevice with integrated contactless conductivity detector is described in detail. Standard CE separations of three inorganic cations in concentrations down to 5 microM show the viability of the new microCE system.     

Effect of H(2)O-CO(2) organization on ovalbumin adsorption at the supercritical CO(2)-water interface

We have studied the formation of water-CO(2) interfaces in the presence of different concentrations of ovalbumin (OVA) by tensiometry and by means of interfacial rheological measurements to obtain some information on the capacity of protein film to stabilize H(2)O in CO(2) emulsion. The formation of pure water-CO(2) interface can be described as a two-step phenomenon.(1) The CO(2) molecules adsorb onto the water surface and then a reorganization of the interface creates a H(2)O-CO(2) cluster network. This organization occurs at a temperature (40 degrees C) higher than the higher temperature limit (10 degrees C) allowing the formation of crystalline structure called CO(2) clathrate.(2) Our results show that ovalbumin adsorption from bulk concentrations higher than 0.0229 g/L inhibits the cluster formation for a CO(2) pressure less than 80 bar. However, for lower concentrations, the more the CO(2) pressure is close to 80 bar, the more OVA adsorption is reduced by the H(2)O-CO(2) cluster network. Moreover, from a pressure of 90 bar, the affinity of OVA for the interface increases and mixed films made of protein molecules and clusters are obtained for the OVA concentrations lower than 1 g/L.     

Chemical profiling and classification of illicit heroin by principal component analysis, calculation of inter sample correlation and artificial neural networks

Artificial neural networks (ANNs) were utilised to validate illicit drug classification in the profiling method used at “Institut de Police Scientifique” of the University of Lausanne (IPS). This method established links between samples using a combination of principal component analysis (PCA) and calculation of a correlation value between samples.Heroin seizures sent to the IPS laboratory were analysed using gas chromatography (GC) to separate the major alkaloids present in illicit heroin. Statistical analysis was then performed on 3371 samples. Initially, PCA was performed as a preliminary screen to identify samples of a similar chemical profile. A correlation value was then calculated for each sample previously identified with PCA. This correlation value was used to determine links between drug samples. These links were then recorded in an Ibase^® database. From this database the notion of “chemical class” arises, where samples with similar chemical profiles are grouped together. Currently, about 20 “chemical classes” have been identified.The normalised peak areas of six target compounds were then used to train an ANN to classify each sample into its appropriate class. Four hundred and sixty-eight samples were used as a training data set. Sixty samples were treated as blinds and 370 as non-linked samples. The results show that in 96% of cases the neural network attributed the seizure to the right “chemical class”.The application of a neural network was found to be a useful tool to validate the classification of new drug seizures in existing chemical classes. This tool should be increasingly used in such situations involving profile comparisons and classifications.     

Addition of a chiral copper reagent derived from propargylic oxazolidininone to aldehydes

[reaction: see text] The copper reagent arising from an optically pure propargylic oxazolidinone was found to react regio- and diastereoselectively with aldehydes, leading, in a one-pot procedure, to the anti homopropargylic amino alcohols derivatives in good yields.     

Synthesis of 3-substituted-4-methyl-5-acetyl-4-thiazoline-2-thione

The reaction of various potassium salts [RNHC(=S)SK, R = N(CH₃)₂, morpholino, piperidino, and hexahydro-1-(1H)-azepinyl] with 3-chloro-2,4-pentanedione in ethanol at 25–30° afforded the 1-acetylacetonyl substitutedaminodithiocarbamates 1–4 [RNHC(=S)SCH(COCH₃)₂]. Under refluxing conditions, the same reactants gave the heterocyclic compounds 5–8. Possible mechanism and supporting ir, nmr and mass spectral data are discussed.     

Multidimensional gas chromatography using a double cool-strand interface

Commercial interfaces for multidimensional gas chromatography (MDGC) are based either on a valve or a pneumatic switching between columns. Both exhibit significant drawbacks and only few suppliers exist. An extremely simple interface has been set up to overcome these limitations without requiring any pneumatic control or valves switching. This new MDGC design is based on the cryo-control of the analyte transfer from the first to the second column through two cool strands of a capillary. This technique is simple to implement and does not require any special column connections. Applications involve non-polar/polar phase combinations, as well as chiral analysis, hyphenation to a conventional mass spectrometer, and olfactometric detection. In contrast to conventional MDGC configuration, the present configuration allows the use of a single oven to operate both columns at different temperatures.     

Stereospecific Bromine Replacement in the Synthesis of 4(e) and 4(a)-Deuterioadamantan-2-ones

Stereospecific introduction of deuterium on the adamantane skeleton has been accomplished with LiAID(OCH₃)₃-CuI.     

关于双光束红外光谱在气固相多相催化反应实时原位表征中气相校正的讨论（英文）

正In a recent contribution [1] to this journal, Guo and co-workers reported on the design of a dual beam FT-IR spectrometer system aiming, among others, at totally removing the contribution of gas-phase species during operando studies of heterogeneous catalytic reactions. The system consists of two identical cells located in two separate FT-IR spectrometers, one being loaded with a catalyst wafer and the other one being     

Using Time‐Resolved Electrochemical Patterning to Gain Fundamental Insight into Aryl‐Radical Surface Modification

Scanning electrochemical microscopy is used to carry out local free‐radical grafting at a gold surface through mild oxidation of an aryl hydrazine. The process can be deliberately controlled by creation of a local pH gradient at the tip. Comparison of the experimental results with simulations shows that the radial expansion of the pH profile in which successful grafting can be accomplished increases with increasing generation time of OH^? and with decreasing initial concentration of the grafting precursor. Furthermore, the radial expansion is faster than the nucleation of the grafting process.     

Three 5H‐indeno­[1,2‐c]­pyridazin‐5‐one derivatives,potent type‐B mono­amine oxidase inhibitors

The structures of three compounds, namely 7‐methoxy‐2‐[3‐(tri­fluoro­methyl)­phenyl]‐9H‐indeno­[1,2‐c]­pyridazin‐9‐one, C₁₉H₁₁F₃N₂O₂, (Id), 6‐methoxy‐2‐[3‐(tri­fluoro­methyl)­phenyl]‐9H‐indeno­[1,2‐c]­pyridazin‐9‐one, C₁₉H₁₁F₃N₂O₂, (IId), and 2‐methyl‐6‐(4,4,4‐tri­fluoro­butoxy)‐9H‐indeno­[1,2‐c]­pyridazin‐9‐one, C₁₆H₁₃F₃N₂O₂, (IIf), which are potent reversible type‐B mono­amine oxidase (MAO‐B) inhibitors, are presented and discussed. Compounds (Id) and (IId) crystallize in a nearly planar conformation. The crystal structures are stabilized by weak C—H⋯O hydrogen bonds. The packing is dominated by π–π stacking interactions between the heterocyclic central moieties of centrosymmetrically related mol­ecules. In compound (IIf), the tri­fluoro­ethyl termination is almost perpendicular to the plane of the ring.