A rapid and powerful method for the direct gas chromatographic analysis of alkanolamines; Application to ethanolamines

Summary The problems of derivative gas chromatography of the alkanolamines have been discussed. It has been demonstrated that the difficulties of direct GC, inherent in the high adsorption affinity and strong retentive interaction of this class of compounds with silaceous supports and stationary liquids, can be overcome by using organic polymer beads, having weakly interacting surface. From a short column containing Tenax-GC under programmed temperature conditions, better than base line resolution of the three ethanolamines can be achieved in less than 8 minutes, as against about an hour by derivative GC and several hours by chemical methods, based on amine functionality. Elution properties, such as retention index and its temperature coefficient, have been determined on Tenax-GC for the ethanolamines. A boric acid precolumn is reported for the first time to completely subtract the alkanolamines. The relative response factors, which are required for precision analysis, have been found to make an interesting comparison for the ethanolamines and their derivatives. Under optimised PTGC conditions, a 4 ft Tenax-GC column has revealed the presence of six impurity peaks with fairly good resolution in a commercial sample of triethanolamine.     

Determining under- and oversampling of individual particle distributions in microfluidic electrophoresis with orthogonal laser-induced fluorescence detection

This report investigates the effects of sample size on the separation and analysis of individual biological particles using microfluidic devices equipped with an orthogonal LIF detector. A detection limit of 17 +/- 1 molecules of fluorophore is obtained using this orthogonal LIF detector under a constant flow of fluorescein, which is a significant improvement over epifluorescence, the most common LIF detection scheme used with microfluidic devices. Mitochondria from rat liver tissue and cultured 143B osteosarcoma cells are used as model biological particles. Quantile-quantile (q-q) plots were used to investigate changes in the distributions. When the number of detected mitochondrial events became too large (>72 for rat liver and >98 for 143B mitochondria), oversampling occurs. Statistical overlap theory is used to suggest that the cause of oversampling is that separation power of the microfluidic device presented is not enough to adequately separate large numbers of individual mitochondrial events. Fortunately, q-q plots make it possible to identify and exclude these distributions from data analysis. Additionally, when the number of detected events became too small (<55 for rat liver and <81 for 143B mitochondria) there were not enough events to obtain a statistically relevant mobility distribution, but these distributions can be combined to obtain a statistically relevant electrophoretic mobility distribution.     

Chelerythrine chloride binding of guanosine in aqueous solution

In this work, the interaction between chelerythrine (CHE) and guanosine is studied using UV-vis and fluorescence measurements at various temperatures. The UV-vis spectra show that the increasing guanosine concentrations result in the decreasing absorption intensity and red shift of CHE E absorption band (267 nm). The fluorescence spectra are fitted to linear analysis, yielding a binding constant of 1.04×104 L/mol at 298.15 K of CHE with guanosine. Besides, with △rHΘm =-8.26 kJ/mol, △rGmΘ = -22.90 kJ/mol,and △rSmΘ = 49.38 J/(mol K) the interaction should be entropy-driven and exterothermic.     

QWIP Status at THALES

Since 2002, the THALES Group has been manufacturing sensitive arrays using QWIP technology based on GaAs and related III–V compounds, at the Alcatel-Thales-III-V Lab (formerly part of THALES Research and Technology Laboratory).In the past researchers claimed many advantages of QWIPs. Uniformity was one of these and has been the key parameter for the production to start. Another widely claimed advantage for QWIPs was the so-called band-gap engineering and versatility of the III–V processing allowing the custom design of quantum structures to fulfil the requirements of specific applications such as very long wavelength (VLWIR) or multi-spectral detection. In this presentation, we give the status of our LWIR QWIP production line, and also the current status of QWIPs for MWIR (<5 μm) and VLWIR (>15 μm) arrays.As the QWIP technology cannot cover the full electromagnetic spectrum, we develop other semiconductor compounds for SWIR and UV applications. We present here the status of our 320 × 256 SWIR module with InGaAs photodiodes.     

Intercalation of Toluidines into α-Zirconium Hydrogenphosphate

Intercalates of o-, m-, and p-toluidine into α-Zr(HPO₄)₂ · H₂O were prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As follows from IR, toludine molecules are protonated in the interlayer space. Toluidine molecules are arranged in a bimolecular way in the intercalates containing more than 1.5 toluidine molecules per Zr atom. On the other hand, a monolayer of the toluidine molecules is supposed in the intercalates with less than one toluidine molecule per Zr atom.     

Semiflexible polymers in a random environment

We present using simple scaling arguments and one step replica symmetry breaking a theory for the localization of semiflexible polymers in a quenched random environment. In contrast to completely flexible polymers, localization of semiflexible polymers depends not only on the details of the disorder but also on the ease with which polymers can bend. The interplay of these two effects can lead to the delocalization of a localized polymer with an increase in either the disorder density or the stiffness. Our theory provides a general criterion for the delocalization of polymers with varying degrees of flexibility and allows us to propose a phase diagram for the highly folded (localized) states of semiflexible polymers as a function of the disorder strength and chain rigidity.     

The search for charge-remote reactions of even-electron anions derived from 1,3-disubstituted adamantanes in the gas phase. Retro Diels-Alder and Norrish II processes

The collision induced decompositions of 3-substituted adamantane carboxylate anions have been studied with a view to uncovering charge-remote fragmentations of the 3-substituent. The 3-substituent is chosen so that it cannot approach the anion site, and so any fragmentations of that substituent should proceed independently of the charged centre, viz. charge-remote reactions. The following systems have been studied (i) the 3-cyclohexenyl system shows no charge-remote retro Diels-Alder fragmentation (DeltaH = +157 kJ mol(-1)), instead, charge-remote loss of the cyclohexenyl radical is noted, (ii) the 3-isobutyl ketone system shows no Norrish II cleavage (loss of C(3)H(6), DeltaH = +18 kJ mol(-1)), instead, the competitive losses of CO(2) from the charged carboxyl centre, together with charge-remote radical loss of the 3-substituent are observed, and (iii) the corresponding 3-isopropyl ester does show the "Norrish II" loss of C(3)H(6), together with competitive losses of CO(2) and the 3-substituent. It is concluded for cases (ii) and (iii), that an adamantane carboxylate anion system with a carbonyl group directly attached at the 3-position is not a suitable model system for studying charge-remote reactions.