Azoles 48 [1]: Synthesis of Some 4-Amino-2-methyl-5-nitro-1-phenacylimidazoles

Summary. Reactions of 1-phenacyl derivatives of 2-methyl-4,5-dinitroimidazole with primary or secondary amines (aniline, morpholine, piperidine, pyrrolidine) yielded the 4-amino-5-nitroimidazole derivatives only.Received January 23, 2003; accepted (revised) February 5, 2003 Published online June 2, 2003     

Fibre optic coupler as a detector for microfluidic applications

A new construction of a fibre optic coupler is presented in the paper. Two polymer optical fibres were used to build a coupler in which coupling efficiency of optical power depends on the refractive index of liquid delivered to a microchannel formed by the fibres. The coupler was tested as a detector in saccharose concentration measurements, and was used in absorbance measurements. A red light emitting diode and a spectrometer were used as a light source and a photodetector, respectively. Experiments confirmed that the coupler can be used for the real time monitoring of the changes in the refractive index of a saccharose solution exhibiting repeatable changes in the signal, with no hysteresis. Absorbance tests were performed with a solution of bromothymol blue at different pH.     

Simultaneous Densitometric Determination of Quinapril and Hydrochlorothiazide in the Combination Tablets

JPC – Journal of Planar Chromatography – Modern TLC - A new, simple, and accurate TLC method, using normal- and reversed-phase techniques and densitometric detection, has been developed...     

Pentamidine Analogs: Syntheses, Structures in Solid State by 13C CP/MAS NMR Spectroscopy, and X-Ray Crystallography and their Preliminary Biological Screening Against Human Cancer

The synthesis of four new 1,5-bis(4-amidinophenoxy)-3-oxapentane analogs is described. The structures of the obtained bis-amidines and bis-nitriles in the solid state are evaluated on the basis of ¹³C CP/MAS NMR spectra and theoretical calculations at DFT level. A single crystal X-ray diffraction structure is presented for 1,5-bis(4-amidinophenoxy)-3-oxapentane. A preliminary anticancer assay against three cell lines is also given.     

Novel approach for the simultaneous analysis of glyphosate and its metabolites

A novel approach for the simultaneous analysis of glyphosate (PMG), and aminomethylphosphonic (AMPA, GlyP), N-methylaminomethylphosphonic (MAMPA. SarP) and methylphosphonic (MPA) acids is presented. This includes a preliminary 31P NMR analysis of mixtures of PMG, MPA, AMPA and MAMPA, their further derivatization to volatile phosphonates by means of the trifluoroacetic acid-trifluoroacetic anhydride-trimethyl orthoacetate reagent and subsequent MS [chemical ionization (CI) MS, GC-CI-MS, GC-electron impact ionization MS] and/or GC-flame ionization detection (FID) analysis of the products of derivatization. The detection limits of PMG, AMPA, MAMPA and MPA by means of GC-CI-MS and GC-FID were determined. The calibration graphs (GC-FID) for these derivatives were in the range 0.1 to 100 nmol linear and sufficiently reproducible for quantitative determinations. The applicability of the method was demonstrated during the analysis of water samples fortified with PMG, AMPA and MAMPA, characterized by recoveries of >95%.     

Adsorption behavior of surface-chemically pure N-alkyl-N-(2-hydroxyethyl)aldonamides at the air/water interface

N-alkyl-N-(2-hydroxyethyl)aldonamides (alkyl: n-C6H13, n-C8H17, n-C10H21, n-C12H25, and n-C14H29) were obtained in the reaction of long-chain N-alkyl-N-(2-hydroxyethyl)amines with D-glucono-1,5-lactone and D-glucoheptono-1,4-lactone. The adsorption isotherms were obtained from surface tension measurements of aqueous solutions of surface-chemically pure surfactants. The experimental equilibrium surface tension versus concentration isotherms were evaluated by the Frumkin adsorption equation to get the adsorption parameters, namely, standard free energy of adsorption, deltaG(o)ad, saturation adsorption, gammainfinity minimum surface area demand per molecule adsorbed, Amin, and interaction parameter, Hs. The investigated functionalized alkylaldonamides show improved solubility in comparison with the corresponding sugar derivatives of the primary amines. The introduction of the -CHOH moiety into the saccharide headgroup causes a noticeable increase of the hydrophobic character of surfactant. The minimum surface area demand, Amin, is slightly greater for glucoheptonamides than for the corresponding gluconamides. The practically constant Amin value within the homologue series of the aldonamides indicates that the obtuse hydroxyethyl residue is the determining factor for the arrangement of the adsorbed surfactants in the interfacial layer.     

Analysis of applying different solvents for the mobile phase and for sample injection

Overloading a chromatographic column with a compound possessing low solubility in the mobile phase has been investigated. In order to increase the concentration of injection a strong solvent for dissolving the feed was used. The injection of such concentrated samples brings the risk of triggering undesired crystallisation processes. A model system has been investigated with ethanol-water as the mobile phase and DL-threonine as the sample dissolved in pure water. Under extreme overloaded conditions band splitting was observed. Measurements of the adsorption isotherms and systematic solubility studies were carried out. For the process analysis a simplified mathematical model was applied. The simulations of the band profiles were compared with the experimental data.     

Choice of the best alternative in case of a continuous set of states of nature-application of fuzzy numbers

On the basis of a known application of an order weighted averaging operator to the decision making in the case of a discrete set of states of nature, a general approach to the case of a continuous set of states of nature is proposed. The general approach encompasses various types of attitudes of the decision maker, expressed in the form of fuzzy numbers.