A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery.     

Synthetic magnetic opals

We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.     

What every chemist should know about plant names

Chemists screen plants for their constituents on a daily basis, and the data gathered is of importance to a wide range of fields such as medicine, evolutionary biology and ecology. However, the use of this data is sometimes impeded by incorrect citation of the species names. In this Viewpoint, I explain why chemists should be aware of the essentials of plant naming, and describe some easy quality checks that can be performed to avoid errors being perpetuated.     

Surface Modification of Banana Fibers by DBD Plasma Treatment

Banana fibers, an environmentally friendly raw material freely available, were physically modified by atmospheric dielectric barrier discharge (DBD) plasma treatment of different dosages. The influence of the plasma treatment applied on the banana fibers was performed considering the mechanical properties, wettability, chemical composition and surface morphology. These properties were evaluated by tensile tests, static and dynamic contact angle, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray diffractometry, conductivity and pH of aqueous extract, differential scanning calorimetry and scanning electron microscopy images. We compare untreated and treated fibers with three different DBD plasma dosages. The results of this study showed considerable modifications in banana fibers when these are submitted to plasma treatment.     

An overview on the standardization of chromatographic methods for screening analysis in toxicology by means of retention indices and secondary standards

Summary A review is presented on the methods of standardization of HPLC data as used in systematic toxicological analysis. In straight-phase HPLC, the best results were obtained with a series of selected drugs as retention standards. In reversed-phase HPLC, various retention index systems were introduced. However, these systems alone cannot compensate large differences in selectivities of nominally identical, but commercially different reversed-phase column packings. Much better results were achieved with selected drugs as retention index markers. The practical applicability of such a standardized HPLC system is demonstrated.Part I see [1]Dedicated to Prof. Dr. Dr. Marika Geldmacher-von Mallinckrodt in recognition of her pioneering contributions in clinical and forensic toxicology     

Model compounds and 13C NMR increments for the characterization of maleic anhydride-grafted polyolefins

A set of model compounds that mimic the graft sites of maleic anhydride (MA) functionalized polyolefins was synthesized and characterized with NMR spectroscopy. The acquired carbon nuclear magnetic resonance data were used to deduce chemical-shift increments for the prediction of ¹³C chemical shifts of MA functionalized polyolefins. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4368–4385, 1999     

A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery. Received: 21 November 1999 / Revised: 10 January 2000 / Accepted: 15 January 2000