Analytical application of embelin

Summary Embelin is employed as a analytical reagent for the estimation of (a) aluminium in solutions of p_H 4.0–4.5 and (b) beryllium in solutions of p_H 6.5–7.0. While aluminium could be estimated both as its complex or as oxide, Al₂O₃, beryllium could be estimated only as oxide, BeO. The reagent is also employed for the separation of beryllium from aluminium.Part I: See Z. analyt. Chem. 175, 114 (1960).     

Analytical application of embelin

Summary Embelin is reported as a new reagent for gravimetric estimation of (1) uranium in pure solutions at p_H 6.0–6.5 and (2) thorium in acid solutions of 0.4 N HCl. In both cases, the precipitates were ignited and weighed as U₃O₈ and ThO₂. The separation of thorium from large excess of uranium and rare earths could also be effected employing this reagent. In addition, Cu, Cd, Ca, Ba, Sr, Al, Be, Mn, Mg and Zn do not interfere.     

Analytical application of embelin

Summary Embelin is employed as a reagent for the gravimetric individual estimation of alkaline earth metals and magnesium.

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Zusammenfassung Zur gravimetrischen Einzelbestimmung von Magnesium und den Erdalkalien wird Embelin als Reagens empfohlen.

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Part III: Z. analyt. Chem. 185, 216 (1962).     

Analytical application of Cherenkov radiation

Data are reported on the development of a Cherenkov photometric producere, applying the basic principle of the method of LOWRY et al. At various amplifications and channel settings, linear correlations may be obtained between the logarithm of the protein content and the external standard activity or the channel ratio. The values obtained by Cherenkov spectrophotometry based on the Filin method display a linear correlation with each other with a good correlation coefficient.     

Analytical application of Cherenkov radiation

Studies were made to establish the possibilities and limitations of the photometric application of Cherenkov radiation. The colour quenching brought about by various coloured substances can be utilized for Cherenkov photometric measurements. The colour quenching is the strongest in the case of yellow, and the least strong for blue; accordingly, the slope of the linear logarithmic correlation between the efficiency and the concentration is higher for yellow than for blue. Glass and plastic vessels alike can be used for the measurements. The measurements have the greatest sensitivity in the case of the external standard. With the aid of an external standard, measurements of very high sensitivity can be made under isotope-free conditions.     

Analytical application of Cherenkov radiation

The application of Cherenkov photometry gives a new possibility in isotope dilution analysis for determination of specific activity in a simple way. If the compound of the isotope is coloured or it can be converted into a coloured compound, it is possible to measure the activity and the concentration of the compound in one sample in one series of measurement. Methods were worked out for the determination of³²P specific activity by measuring the³²P efficiency, activity and the phosphorus content of the same sample. It is possible to measure the specific activity in an automatic mode with some modification of the liquid scintillation spectrometer.     

Analytical application of differential staircase voltammetry

Summary Differential staircase voltammetry is a technique which utilizes the measurements of the dc-component of differential pulse voltammetry. The analytical applicability of the method was estimated using some well-known electrochemical systems. It could be shown that the detection limits of differential staircase voltammetric determinations are almost equal those obtained with differential pulse voltammetry.     

Synthesis and biological evaluation of hydrophilic embelin derivatives

In continuance of our search for newer anti-cancer agents we were interested on embelin, a XIAP (X-linked inhibitor of apoptosis protein) inhibitor. This natural benzoquinone bear a lipophilic chain and we report here the synthesis of hydrophilic analogues of embelin. To allow a large flexibility in the nature of the hydrophilic group, three amines with different length of carbon chain bearing a protected benzoquinone were prepared. The cytotoxic effects of these derivatives were evaluated on KB cell line.     

Analytical application of high-molecular quaternary ammonium salts

Summary The anion-exchange extraction of a great number of mineral, organic and metal complex anions by solutions of quaternary ammonium-salts (QAS) in different solvents, including intermediate exchange with acidic dye anions, has been investigated. Extraction-photometric methods and ion-selective electrodes for the determination of organic and metal complex anions have been developed. Simple methods for synthesis and purification of QAS are described and their self-association has been investigated by electroconductivity and interphase distribution.

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Analytische Anwendung von hochmolekularen quaternären Ammoniumsalzen

     

Multilayered electrospun nanofibrous scaffolds for tailored controlled release of embelin

Polymeric electrospun meshes are highly attractive as versatile platforms for numerous biomedical applications, tissue engineering, biosensors, and controlled release of bioactive agents. Herein, we describe the preparation and characterization of multilayered nanofibrous poly(ε-caprolactone) scaffolds with different embelin content by electrospinning technique. In vitro release in physiological and acidic pH and kinetic analysis were performed. The results show that it is possible to modulate the release profile depending on the number and thickness of layers added to drug-loaded scaffold that acts as an embelin reservoir. Electrospun multilayered scaffolds present characteristics, morphology and release profiles that could be very attractive for use as embelin controlled release systems.     

Analytical application of liquid adsorption chromatography of metal chelates

Summary A review of the most important achievements in the application of liquid adsorption chromatography (LAC) of metals as chelates is given. The advantages of the method in combination with an extraction preconcentration of metals are pointed out. The general problems of LAC of chelates (choice of a chelating reagent, requirements for chelates, conditions of formation and separation of complexes) are discussed. The applications of TLC and HPLC are considered separately. Special attention is paid to the analysis of specific objects. The analytical possibilities of TLC and HPLC are compared as applied to the separation and determination of metal chelates. The fields of application and the perspectives of developing the methods in inorganic analysis are estimated.

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Analytische Anwendung der Flüssig-Adsorptions-Chromatographie von Metallchelaten

     

Analytical investigations on cephalosporins--IV: application of Ellman's reagent

The application of 5,5'-dithiobis(2-nitrobenzoic acid) (Ellman's reagent) for the determination of microgram quantities of various selected cephalosporins in aqueous solution is described. Cephalosporin derivatives (cephalothin sodium, cephacetrile sodium, cefamandole lithium and nafate, cefoperazone sodium and ceftizoxime sodium) have to be treated with 0.5N sodium hydroxide before determination with Ellman's reagent, which reacts with free thiol groups. An aliquot of the solution is reacted with Ellman's reagent in pH 7.2 phosphate buffer and the absorbance of the resulting yellow solution is measured at 410 nm. The method, which is simple and precise, has been applied to determination of those cephalosporins in formulations, the results being compared with those obtained by the Ni-hydroxylamine method.     

Analytical application and spectrophotometric study of the scandium-indoferron complex

A new spectrophotometric method for microgram amounts of scandium with indoferron is described. The molar absorptivity is 960 l.mole⁻¹.mm⁻¹ at 600 nm. Uranium and the rare earths do not interfere, if present in amounts less than 50 μg. Scandium in silicate rocks can be determined by the procedure after separation of the scandium by a three-stage ion-exchange Chromatographic technique. The acid dissociation constants of indoferron and conditional formation constants of the 1:2 complex have been determined spectrophotometrically.     

Analytical application of second-harmonic a.c. polarography

Phase-selective second-harmonic a.c. polarography can be used to distinguish two different species having similar reduction potentials. Because each species has a different phase angle depending on the electrode kinetics, a certain phase angle can be chosen to detect only one component in the mixture. In 1 M potassium chloride solution, indium-(III) at the 4 × 10^-6 M level can be determined in the presence of 50-fold amounts of cadmium(II), and zinc(II) at the 2 × 10^-5 M level in the presence of 100-fold amounts of nickel(II).     

Recent developments in synthesis of embelin heterocyclic derivatives and their biological applications

Embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone) has attracted a great deal of synthetic attention as a biologically active heterocyclic compound in the last decades. The high reactivity of its carbonyl groups, active methylene group, and hydroxyl groups represents challenges to many organic reactions for the synthesis of various embelin derivatives. This review summarizes for the first time the most recent and relevant approaches towards the synthesis of embelin-linked heterocyclic derivatives.     

Analytical application of phenylbenzene sulphazide in separation and determination of selenium

In this paper the utility of phenylbenzene sulphazide is illustrated by its application to the determination of selenium and the separation of this element from tellurium, lead, copper, bismuth, nickel and iron. Selenious acid is reduced to black selenium in acid media at 100 degrees . To minimize interference by other elements but yet give rapid recoveries of selenium an acidity of 40% (v/v) formic/acetic acid is recommended. The co-precipitation of tellurium is prevented by adding tartaric acid. Oxalate, tartrate, citrate, EDTA and phosphate do not interfere.     

Analytical application of x-ray radiation induced by radioactive isotopes,I

The dependence of the intensity of the bremsstrahlung and the characteristic X-radiation induced by a beta-emitting¹⁴C-isotope was investigated as a function of the layer thickness and the atomic number of the absorbent. The theoretically calculated and measured values of layer thickness required for maximum radiation intensity were in good agreement. The atomic number values required for maximum bremsstrahlung and characteristic radiation were ascertained. The obtained extreme values were attributed to a resonance effect occurring by the interaction of β-particles with theK electrons of the absorbent.     

Organothiophosphorus compounds as inductors of the iodine-azide reaction. Analytical application

Thiophosphoryl compounds were found to exhibit strong induction activity in the iodine-azide reaction. On this basis three procedures for their determination: titrimetric (0.15-1 mumol), coulometric (1-20 nmol) and spectrophotometric (0.5-5 nmol) have been developed. RSD in all applied methods (techniques) have been found at the 1-7% level. The induction coefficients were dependent on the type of compound applied and on the reaction condition and varied from 90 to 450.