Untersuchungen zur Bestimmung von Spurenelementen in Blutserum mit Hilfe der Totalreflexions-R?ntgenfluoreszenzanalyse

Summary The quantitative determination of trace elements in human blood serum by Total Reflection X-Ray Fluorescence Analysis (TXRF) is influenced by absorption- and reflection-effects caused by the organic (proteins) and inorganic (P, S, Na, K, Ca, Cl) matrices. To minimize these effects we have developed a sample preparation technique based on the decomposition of the organic matrix and followed by the separation of the trace elements from the organic matrix by ion-exchange. The described method enables the simultaneous determination of K (1584 g), Ca (666 g), Fe (22 g), Cu (9.6 g), Zn (8.8 g), Se (0.97 g), Sn (1.3 g), Pb (0.12 g) and Rb (1.6 g) (obtained values in parentheses).

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Herrn Prof. Dr. G. Tölg zum 60. Geburtstag gewidmet     

Influence of the crystallite size of platinum of the course of hydrogenolysis of ethane and propane over Pt/Al2O3 catalysts

The effect of the degree of platinum crystallite size on the reaction rate, selectivity and activation energy of ethane and propane hydrogenolysis has been studied in the range of platinum crystallite size of 1.7–4.0 nm. In the same range of Pt crystallite size, the activation energy of both processes shows a clear minimum. The decrease in Pt crystallite size bellow 3.0 nm brings about rapid changes in the selectivity of propane hydrogenolysis.

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( ) , -. 1,7–4,0 , .

     

Structure and reactivity of vanadium-phosphorus oxides

The contribution of thermal methods of analysis to the study of the structure and reactivity of vanadium-phosphorus oxides is examined. In particular, data are reported on the solid-state reaction VOHPO₄·1/2H₂O(VO)₂P₂O₇+2 H₂O for VOHPO₄·1/2H₂O prepared in different ways, on the redox properties of oxidation and reduction of vanadium for catalysts prepared with different PV atomic ratios in the range 0.9–1.3, and on the surface properties determined by TPD of catalysts with different PV ratios. The relationship between these properties and the catalytic properties in the selective oxidation ofn-butane and but-1-ene is discussed.

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Zusammenfassung Der Beitrag thermischer Analysenmethoden zur Untersuchung der Struktur und Reaktivität von Vanadin-Phosphor-Oxiden wird erörtert. Insbesondere werden sich auf die Festkörperreaktion 2VOHPO₄.1/2H₂O(VO)₂P₂O₇+2H₂O für auf verschiedene Weise dargestelltes VOHPO₄.1/2H₂O, auf die Redox-Eigenschaften von Vanadin in Katalysatoren mit P/V-Atomverhältnissen im Bereich 0.9–1.3 und auf durch TPD bestimmte Oberflächeneigenschaften von Katalysatoren mit unterschiedlichen P/V-Verhältnissen beziehende Angaben gemacht. Zusammenhänge zwischen diesen Eigenschaften und den katalytischen Eigenschaften bei der selektiven Oxydation von n-Butan und N-Buten werden diskutiert.

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- . , VOHPO₄ · 1/2H₂O, VOHPO₄ · 1/2H₂O(VO)₂P₂O₇ + 2H₂O, - PV 0,91,3. - 1-.

     

The Aggregation of Cyclodextrins as Studied by Photon Correlation Spectroscopy

Photon correlation spectroscopy has been used to study theaggregation processes of natural and some modified cyclodextrins (CDs) in diluted aqueoussolutions. -, -, and -CD form large, polydisperse aggregatesin water, although the aggregation capability is different depending on the macrocycle considered. -CD solutions filtered through 0.2~m give a single-modaldistribution of aggregates of 224 nm in size. The monomeric -CD can be isolated by filtering through 0.1 m. -CD displays a bimodaldistribution (monomer + aggregates) with both pore sizes. At the concentrations studied (0.012 M) the contribution in mass of the aggregates with both CDs isnegligible. -CD is much more persistent in its aggregation, even after sievingits solutions through 0.02 m filters, and time dependent. The aggregation displayed byCDs with partial substitution of the OH groups (Methyl--CD and Hydroxypropyl--CD) is much weaker, indicating the implication of the hydrophilic rims ofthe CDs in the process. High temperatures, addition of urea or electrolytes andionisation of the OH groups by raising the pH, prevent the aggregation.     

Thermal properties of binary polyolefin blends

The thermal properties of binary polyolefin blends (LDPE/HDPE, LDPE/PP, HDPE/PP) were examined by differential scanning calorimetry. The additon of a second polymer lowers the melting temperature although the melting temperature depression is not a defined function of the blend composition. DSC curves show two melting and two crystallization temperatures. The difference between crystallization temperatures for blends containing PP is smaller than the difference between melting temperatures. The enthalpies of fusion are nearly monotonic functions of blend composition.

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Zusammenfassung Die thermischen Eigenschaften binärer Polyolefinmischungen (LDPE/HDPE, LDPE/PP, HDPE/PP) wurden mittels DSC untersucht. Durch Zugabe eines zweiten Polymers wird die Schmelztemperatur erniedrigt, obwohl die Erniedrigung der Schmelztemperatur keine Funktion der Mischungszusammensetzung ist. Die DSC-Kurven zeigen zwei Schmelz- und zwei Kristallisationspeaks. Bei PP enthaltenden Mischungen ist der Unterschied zwischen den Kristallisationstemperaturen geringer als zwischen den Schmelztemperaturen. Die Schmelzenthalpie ist eine nahezu monotone Funktion der Mischungszusammensetzung.

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— , — , — . , . . , . .

     

Trace analysis of cationic surfactants in water using HPLC with conductometric detection

Summary A simple and fast determination of trace amounts of commercially used cationic surfactants is described. After extraction from water cationic surfactants are separated by HPLC and detected by conductometry. The detection limit is 3 g/l for distearyldimethylammonium chloride, 16 g/l for ditallowimidazolinium methosulphate, and 6 g/l for dodecylpyridinium chloride.     

Kombinierte derivatographische und thermogastitrimetrische Untersuchungen von Verbindungen,die Unter Abspaltung von Ammoniak Zerfallen

Zusammenfassung Verfasser untersuchten mit Hilfe der kombinierten derivatographischen und thermogastitrimetrischen Methode die thermische Zersetzung von Ni(NH₃)₆Cl₂, ZnNH₄PO₄ und MnNH₄PO₄ · H₂O. Die Untersuchungen wurden in Stickstoffatmosphäre ausgeführt. Es wurde festgestellt, daß sich das entweichende Ammoniak in geringem Maße in allen drei Fällen zersetzt. Die Zersetzung des Ammoniaks erfolgte immer nur in der letzten Periode der Untersuchungen, d. h. bei höheren Temperaturen. Es wurde ferner gefunden, daß in den untersuchten Ammoniumphosphatverbindungen die Abspaltung von Ammoniak und die Freisetzung von Wasser nahezu gleichzeitig, in zwei voneinander nicht trennbaren Vorgängen verläuft.

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A complex derivatographic and thermogas-titrimetric method was used for the investigation of Ni(NH₃)₆Cl₂, ZnNH₄PO₄ and MnNH₄PO₄ · H₂O. The ammonia liberated during thermal treatment was found to decompose to a small extent for all three compounds in the final stage of the investigation, i.e. at high temperatures. It was also found that ammonia and structural water left practically simultaneously and not in two independent, separate steps.

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Résumé On a étudié la décomposition thermique de Ni(NH₃)₆Cl₂, de ZnNH₄PO₄ et de MnNH₄PO₄ · H₂O dans l'azote, en combinant l'emploi du Derivatograph avec le titrage des gaz dégagés. Pour les trois composés, on a observé une légère décomposition de l'ammoniac dégagé, pendant l'étape finale de la décomposition, c'est-à-dire aux températures élevées. Dans le cas des phosphates ammoniacaux, l'ammoniac et l'eau se dégagent presque en même temps et non en deux étapes successives.

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- Ni(NH₃)₆Cl₂, ZnNH₄PO₄ MnNH₄PO₄·H₂O. , , , . . . , .

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Teilweise vorgetragen an der 3. Ungarischen Konferenz für Analytische Chemie, Budapest, August 1970.     

The interconversion of orthorhombic chromium oxy-hydroxide and chromium dioxide

The thermal behaviour of CrOOH and CrO₂ in different atmospheres has been studied by means of DTA, TG and X-ray diffraction. The easy interconversion between the two substances at one atmosphere pressure is explained on the basis of the results obtained.

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Zusammenfassung Es wurde das thermische Verhalten von CrOOH und CrO₂ in verschiedenen Atmosphären mit Hilfe der Differentialthermoanalyse, Thermogravimetrie und Röntgendiffraktion untersucht und auf Grund der Ergebnisse die leichte Umwandlung wischen den zwei Verbindungen unter 1 Atm. Druck erklärt.

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Résumé Étude du comportement thermique de CrOOH et de CrO₂ dans différentes atmosphères, par ATD, TG et diffraction de rayons X. Interprétation de l'interconversion légère entre les deux substances sous une pression d'une atmosphère.

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lO₂ , -. , .

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Thanks are due to Prof. Dr. S. C. Bevan of Brunei University and to Dr. E. Hockings of RCA (USA) for valuable discussions, and also to the D.G.E.S.I. (Spain) for a grant (to M.A.A.F.).     

Formation of allyl radicals in the adsorption of propylene on zinc oxide

It has been found by the ESR technique that the adsorption of propylene on zinc oxide leads to the formation of a -allyl radical. It is suggested that the radical species of the surface allyl compound on this catalyst is responsible for its high selectivity in the dehydroaromatization of propylene to benzene.

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, - . , .

     

Unusual selectivity in photooxygenation of alkanes by air in CH3CN solutions catalyzed by CrCl3?C6H5CH2N(C2H5)3Cl

A new system CrCl₃–C₆H₅CH₂N(C₂H₅)₃Cl–CH₃CN for photooxygenation of alkanes is suggested. Unlike metal chlorides and oxocomplexes, it oxidizes alkanes to produce ketones and small amounts of alcohol. Adding of benzene, methylene chloride or ethanol to the cyclohexane solution rises the oxygenation rate and changes the ketone/alcohol ratio. With small amounts of hydroquinone the formation rate of cyclohexanone (but not of cyclohexanol) sharply decreases. Kinetic isotope effect in the oxidation of C₆H₁₂ and C₆D₁₂ is 1 for cyclohexanol and 2.9 for cyclohexanone. Cyclohexanol formation is assumed to follow a mechanism that does not involve free radicals. Free radicals can participate in the route toward ketone.

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CrCl₃–C₆H₅CH₂N(C₂H₅)₃Cl–CH₃CN . , . , /. ( ) . C₆H₁₂ C₆D₁₂ 1 2,9 . , , . , .

     

Cracking of cumene on vanadium doped silica-alumina

The influence of small admixtures of vanadium on the activity of a silica-alumina catalyst in cumene cracking has been investigated. A correlation has been established between the catalytic and acidic properties of the vanadium doped catalyst.

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. .

     

Lead Zirconate-Titanate Films Prepared from Soluble Powders

Precursor powders for Pb(Zr1 – xTix) O3 (PZT) thin films were produced by the reaction of zirconium-and titanium-n-propoxides with acetylacetone and lead acetate trihydrate. The subsequent complete removal of volatile components yielded powders that can be handled in air. The powders are indefinitely stable under ambient conditions.High molarity (>2m) coating sols were prepared by dissolution of the precursor powders in mixtures of 1,3-propanediol, triethanolamine (TEA) and water. Excess amounts of lead to compensate lead loss during firing were easily introduced into these solutions.The deposition of these sols on steel substrates and firing at 600°C yielded PZT films. Many physical parameters like film thickness, morphology and electrical performance could be influenced by choice of the solvent mixture composition and oxide content of the sols. Depending on the preparation dielectric permittivities, r of up to 840 were measured at 1 kHz. By hysteresis measurements at 50 Hz and a field amplitude of 50 V/m a remanent polarization of about 40 C/cm2 and coercivity of about 8 V/m was obtained. The films were stable against dielectric breakdown up to 70V/m.     

Carbon content and H2 chemisorption of a regenerated Pt catalyst

The effect of the cracking of¹⁴C-labelled cyclohexene on the chemisorption (thermodesorption) of hydrogen on a thermally treated Pt powder catalyst has been studied. It has been established that (i) under the usual conditions of regeneration (calcination of the catalyst at 500°C for 1–2 hrs in a stream of air) the products of cracking cannot be completely removed from the catalyst, and (ii) as compared with the pure catalyst, the carbon deposit content of the catalyst not only increases the amount of chemisorbed hydrogen but also leads to new desorption peaks on the thermodesorption curve.

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, C¹⁴, () . (1) ( 500°C 1–2 ) (2) - - , : .

     

Synthesis,characterization and crystal structures of heterometallic trinuclear carbonyl sulfido clusters (η5-Cp)MoFeCo- (CO)8(μ3-S) and [(η5-Cp)Mo]2Fe(CO)7(μ3-S)

HFe2Co(CO)9(3-S) reacts with (5-Cp)Mo(CO)3Cl in refluxing THF to give heterometallic trinuclear clusters (5-Cp)MoFeCo(CO)8(3-S) and [(5-Cp)Mo]2Fe(CO)7-(3-S), which have been characterized by elemental analyses, i.r., 1H- and 13C-n.m.r. and X-ray crystal structure determination. An electrophilic addition–elimination sequence is proposed for their formation.     

Thermal analysis of some complexes LH[Cr(NCS)4L2].xH2O (L=NH3 or organic base)

Data obtained by thermal analysis of K₃[Cr(NCS)₆].4H₂O and some derivatives, LH[Cr(NCS)₄L₂].xH₂O, where L=NH₃ or an organic base, are reported. The TG, DTG and DTA curves show common behaviour (SCN^– ligand decomposition) as well as specific behaviour for each complex due to the base L, which complicates the thermal decomposition of the complexes. Some weak bases with low boiling points are easily eliminated, which determines the common thermal behaviour of the complexes.A general mechanism of thermal decomposition is advanced involving dehydration and decomposition processes for both LH⁺ and [Cr(NCS)₄L₂]^–. The apparent activation energies of different processes confirm the thermal decomposition mechanisms of the complexes under study.

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Zusammenfassung Die thermische Analyse von K₃[Cr(NCS)₆].4H₂O und einigen Derivaten der allgemeinen Formel LH[Cr(NCS)₄L₂].xH₂O (L=NH₃ oder eine organische Base) betreffende Daten werden angegeben. Die TG-, DTG- und DTA-Kurven zeigen sowohl gemeinsame Charakteristika (Zersetzung des Liganden SCN^–) als auch für jeden Komplex spezifische, durch die Base L bedingte Züge, die die thermische Zersetzung der Komplexe komplizieren. Einige schwache Basen mit niedrigen Siedepunkten werden leicht eliminiert, was ein gleiches thermisches Verhalten dieser Komplexe zur Folge hat. Ein allgemeiner Mechanismus der thermischen Zersetzung wird angegeben, der die Dehydratisierung und die Zersetzungsprozesse sowohl für LH⁺ als auch für [Cr(NCS)₄L₂]^– in sich einschließt. Die scheinbaren Aktivierungsenergien der verschiedenen Prozesse sind mit dem Mechanismus der thermischen Zersetzung der Untersuchten Komplexe im Einklang.

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K₃[Cr(NCS)₆].4H₂O LH[Cr(NCS)₄L₂].x₂, L=NH₃ - . , - , , . , . , LH⁺ [Cr(NCS)₄L₂]^–. .

     

Ab initio calculations for adsorbed state of OH group on Ni(110)

Ab initio quantum-chemical calculations of OH radical adsorption on Ni(110) have been carried out in cluster approximations. It is shown that unlike energy calculations of adsorbed complexes, their vibrational frequencies must be calculated with taking into account 3d orbitals of Ni.

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OH Ni(110) . , , 3d-.

     

Anwendung der Ringofenmethode zum Nachweis einiger Heteroelemente in organischen Verbindungen

Zusammenfassung Ein schnelles und einfaches Mikroverfahren zum Nachweis einiger Heteroatome organischer Verbindungen wurde entwickelt. Nach Aufschluß mit metallischem Kalium werden die entstehenden Ionen mit der Ringofenmethode getrennt und mit empfindlichen Reaktionen nachgewiesen. Nachweisgrenze: 0,5 bis 1g Stickstoff, 1 bis 2g Schwefel, 2 bis 3g Jod, 4 bis 5g Brom, 5 bis 10g Chlor in 0,5 bis 1 mg Einwaage.

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Summary A rapid and simple micromethod was developed for the detection of several hetero-elements in organic compounds. After breaking down the sample with metallic potassium, the resulting ions are separated by the ring oven method and detected by means of sensitive reagents. Detection limits: 0.5 to 1g nitrogen, 1 to 2g sulfur, 2 to 3g iodine, 4 to 5g bromine, 5 to 10g chlorine in samples weighing 0.5 to 1 mg.

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Résumé On a découvert un procédé à l'échelle micro, simple et rapide, pour rechercher certains hétéroéléments dans les composés organiques. Après mise en solution par le potassium métallique, on sépare les ions formés suivant la méthode du four annulaire et l'on effectue la recherche au moyen de réactions sensibles. Limite de dilution: 0,5 à 1g d'azote, 1 àg de soufre, 2 àg d'iode, 5 à 10g de chlore sur 0,5 à 1 mg de prise d'essai.

     

Simultaneous determination of cobalt,nickel and iron by multi-wavelength spectrophotometry

A method for the simultaneous spectrophotometric determination of cobalt, nickel and iron based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is proposed. The absorption curves of these complexes overlap severely in the scanning range 390–510 nm. The analyte concentrations are calculated by a least squares fit of the pure spectra to the mixture spectra, which therefore makes the simultaneous determination of these metallic ions possible without tedious pretreatment. The detection limits afforded by the proposed method range from 0.05 g/ml for Fe and Ni to 0.1 g/ml for Co. Root-mean-squared errors of prediction of 0.085 g/ml for Co, 0.048 g/ml for Ni and 0.1172 g/ml for Fe were obtained using the wavelength range 400–510 nm and 0.147 g/ml for Co, 0.107 g/ml for Ni and 0.127 g/ml for Fe using the wavelength range 420–434 nm. The effect of interferences is studied and the proposed method is applied to analysis for the above elements in synthetic samples and real samples, such as biological materials and alloys.     

Accurate reflectance measurements in the infrared spectral range using an integrating sphere

An integrating sphere is used together with a Fourier transform spectrometer for directional-hemispherical reflectance measurements in the spectral range from 1m to 15m. Comparisons with PTB's fundamental sphere reflectometer around 1m show that the uncertainty of the infrared measurements is ±0.01.     

Simultaneous determination of neodymium and erbium in rare earth mixture with 5,7-dibromo-8-hydroxyquinoline and TX-100 by third-derivative spectrophotometry

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 5,7-dibromo-8-hydroxyquinoline in the presence of octylphenol poly(ethyleneglycol)ether have been studied by normal and third-derivative spectrophotometry. The proposed method is free of interference of other rare earths. The calibration graphs were linear up to 18 g/ml of neodymium and 21 g/ml of erbium (in the final solution). The derivative molar absorptivities are 395 l.mol^–1.cm^–1 for neodymium and 3421.mol^–1.cm^–1 for erbium. The corresponding values of Sandell's sensitivity were 0.36 and 0.49 g.cm^–1, respectively. The relative standard deviations evaluated from ten independent determinations of 2.5 g/ml of neodymium and erbium are 1.5 and 3.8% for neodymium and 1.8 and 4.1% for erbium in absence and presence of 70 g of lanthanum, respectively. The detection limits (signal to noise ratio=2) are 0.23 g/ml for neodymium and 0.30 g/ml for erbium. The method has been used for the determination of neodymium and erbium in mixed rare earths with satisfactory results.