Reconocimiento de nicotina en una hebrita de tabaco

Summary Adaption of theLuís method for the detection of nicotine to microscale, usingEmich's capillary technic proved successful, attaining identification limit of 0,03g.Applying a sub-micro steam distillation effect, the nicotine in a speck of tobacco (1 mm² and less) could still be detected by using the above reaction.Extension of the above procedure to mixtures of nicotine with substances not volatile with steam, inorganic (halides) as well as organic compounds (other alkaloids, acids, etc.) proved to be successful, even when the nicotine is present in proportions of only 1 part in 1000.

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Zusammenfassung Die Anwendung der Kapillartechnik vonEmich zum Nachweis von Nikotin nachLuís war erfolgreich und zeigte eine Erfassungsgrenze von 0,03g.Bei Anwendung einer Ultramikrodampfdestillation kann das Nikotin nach obiger Methode noch in Spuren von Tabak (1 mm² und weniger) nachgewiesen werden.Die Reaktion ist auch positiv bei Gemischen von Nikotin mit anderen, mit Wasserdampf nicht flüchtigen sowohl anorganischen (Halogenide) als auch organischen Substanzen (andere Alkaloide, Säuren etc.), selbst dann noch, wenn das Nikotin bloß im Verhältnis von 11000 vorhanden ist.

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Résumé La technique capillaire d'Emich a été utilisée avec succès pour identifier la nicotine suivant le procédé deLuís; la limite de sensibilité est alors de 0,03g. La mise en oeuvre d'un ultramicroentraînement à la vapeur permet en outre, par application de la précédente méthode, d'identifier la nicotine dans des traces de tabac (moins de 1 mm²). La réaction est également positive en présence d'autres substances non entraînables par la vapeur d'eau, qu'elles soient minérales (halogénures) ou organiques (autres alcaloïdes, acides, etc. ...) même si la proportion de nicotine n'est que de l'ordre de grandeur de 1/1000.

     

IAEA quality control studies on determining trace elements in bioindicators

Twenty laboratories from 17 countries around the world participated in two analytical quality control exercises, coded NAT-5 and NAT-6, on determining trace and minor elements in plant bioindicator samples. 1398 laboratory mean values for 51 elements were submitted for two lichen and two moss materials. The submitted measurement results were evaluated as interlaboratory comparison (IC) exercises and as proficiency tests (PT) following standard procedures developed by the International Atomic Energy Agency (IAEA). The evaluations confirmed good performance of the participating laboratories for many elements. Furthermore, the laboratories performance based on IC criteria improved from the first exercise to the second one. Subsequent NAT-5 evaluation revealed systematic differences between the analytical values obtained non-destructively or after the total sample dissolution and the measurements following nitric acid sample dissolution (without the use of hydrofluoric acid) for some elements. The most critical elements for this kind of discrepancies appeared to be Al, Ca, Cr, Fe, Na, Ni, and Pb. After changing analytical methodologies in the concerned laboratories, more consistent values for those elements were obtained in NAT-6. This revised version was published online in August 2006 with corrections to the Cover Date.     

Some reactions of systems containing the imidazole ring

Behavior towards sodamide is compared for 3-benzyl- and 3-methyl substituted naphth [1, 2-d] imidazole and imidazo [4, 5-f] quinoline derivatives. The following are synthesized: 2-amino derivatives of 3-benzylnaphtho- [1, 2-d] imidazole(by direct animation), and of 3-benzylimidazo [4, 5-f] quinoline (ammonolysis of a 2-chloro substituted compound).     

Synthesis and Structure of Triphenylbismuth Bis(Fluorobenzoates)

The reaction between triphenylbismuth, hydrogen peroxide, and 3,4,5-trifluorobenzoic or pentafluorobenzoic acid (molar ratio 1 : 1 : 2, respectively) in ether gave triphenylbismuth bis(3,4,5-trifluorobenzoate) (I) and triphenylbismuth bis(pentafluorobenzoate) (II) in 74 and 89% yields, respectively. The structures of compounds I and II were established by X-ray diffraction. The Bi atoms have a distorted trigonal-bipyramidal coordination with acylate groups in the axial positions. The OBiO angles are 170.2(2)° and 171.5(2)° in I and II, respectively. The Bi–C(Ph)_eq bond lengths vary in the range of 2.187(6)–2.204(5) Å, the Bi–O(acyl) lengths are 2.256(5) Å in I, and 2.281(5) and 2.318(5) Å in II. In the crystals I and II, the Bi and carbonyl O atoms are involved in intramolecular interactions (Bi···O(=C) 2.926(5)–3.176(5) Å), which increase the equatorial CBiC angles on the side of these contacts to 136.2(3)° and 138.6(2)° in I and II, respectively.     

Study of the cerium(IV)-picrate system in acetonitrile

A potentiometric and spectrophotometric study has been made of the reaction between hexanitratocerate and picrate in dry acetonitrile. Several cerium(IV)-picrate complexes are formed; the formation constant for the first is estimated to be 4 from spectrophotometric measurements. The catalytic effect of picrate on hydroquinone oxidation by nitratocerate is postulated to be due to more rapid electron transfer by cerium picrate complexes.     

Effects of structural transformations in magnetic emulsions

Structural transformations and relevant changes in the magnetic and optical properties of magnetosensitive emulsions based on magnetic fluids are experimentally studied. Peculiarities of the changes in the magnetic susceptibility of emulsions associated with the deformation of their microdroplets and the effect of phase inversion (the transformation of dispersions of magnetic droplets in nonmagnetic media into dispersions of nonmagnetic droplets in magnetic fluids) are established. Optical effects occurring in magnetic emulsions under the combined action of a shear flow and a magnetic field are studied. It is concluded that optically active composition media may be developed on the basis of magnetic fluids.     

Structural relationships in close-packed AB2O4 oxides involving spinel,olivine, and hexagonal LiFeSnO4 structures

Close-packed structures with formula AB₂O₄ were studied in terms of polyhedra arrangement. The junction between octahedral layers (kagome) and mixed (octahedral and tetrahedral) layers were analyzed; this association allows one to determine two types of double layers whose packing leads to three closely related structural types: spinel, double-hexagonal LiFeSnO₄, and a hypothetical hexagonal structure. Olivine structure shows a polyhedral arrangement closely related to those of these three structures and can be described alike in terms of mixed layers and double layers. AB₂O₄ close-packed oxides can exhibit polymorphism; from this analysis a mechanism, involving geometrical operations applied to the double layers, is proposed for the different transitions, really observed as (DH) LiFeSnO₄ spinel and olivine-spinel or theoretical as (DH) LiFeSnO₄—hypothetical hexagonal and olivine—hypothetical hexagonal.     

Die spezifische Extraktion von Uran(VI) mit N-Benzylanilin und N-Butylanilin

Zusammenfassung Zwei Methoden zur extraktiven Abtrennung des Urans von einer Reihe von Ionen werden beschrieben. Die Extraktion erfolgt aus schwefelsaurer Lösung mit N-Benzylanilin bzw. N-Butylanilin, gelöst in Chloroform. Nach Reextraktion mit Wasser erfolgt die quantitative Bestimmung mit PAR.

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Summary Two methods for the extractive separation of uranium from a number of ions are described. The extraction is from a solution containing sulfuric acid by means of N-benzylaniline or N-butylanilin, dissolved in chloroform. After reextraction with water, there follows the quantitative determination with PAR.

     

Synthesis and Heterocyclization of 3-Arylaminothiocrotonanilides

Reactions of acetylthioacetanilide with arylamines in acetic acid in the presence of sodium acetate give 3-arylaminothiocrotonanilides in good yields. When treated with -bromoacetophenone in acetone, these products are converted to substituted 4-hydroxy-²-thiazolinium bromides, one of which was dehydrated to obtain the corresponding thiazolium bromide. The structure of the heterocyclization products was confirmed by single crystal X-ray diffraction and NMR study of 2-acetonylidene-3,4-diphenyl-2,3-dihydrothiazole formed by dehydration of the corresponding ²-thiazolinium salt with simultaneous hydrolysis.