Solid sampling analysis by means of autoprobe-GFAAS

Summary A recently developed solid sampling graphite system for automatic probe atomisation (SAP-GFAAS) was applied for the direct determination of Pb and Cd in untreated bovine liver matrix.The study was based on 30 livers with a low content of lead (0.045 to 0.27 g Pb/g fresh matter) and of cadmium (0.031–0.24 g Cd/g fresh matter). The basic comparative data for the evaluation of the SAP-GFAAS method were supplied by a standardized GFAAS method with preliminary sample homogenization and matrix decomposition. Additionally, data were obtained by two further solid sampling methods: a front entry graphite system with direct Zeeman effect background correction and a side entry graphite system with high-energy deuterium continuum background correction. The combination of the autoprobe technique and solid sampling was shown to provide analytical results — in terms of handling, accuracy and precision — comparable to those obtained by means of the conventional solid sampling systems. Differences between the results of the sample decomposition method and the solid sampling methods, as well as between the three solid sampling methods must be regarded as being of no practical significance. Part I: see [1].     

Certified reference materials for thermal analysis

Eight inorganic substances recommended by ICTA as temperature standard reference materials for DTA and DSC were studied: KNO₃, KClO₄, Ag₂SO₄, K₂CrO₄, quartz, K₂SO₄, BaCO₃ and SrCO₃. The content of pure component in each of these substances was determined by classical chemical analysis. The temperatures and the heats of polymorphic transformations of these substances were measured with a Perkin-Elmer DSC-2 differential scanning calorimeter, and DTA studies were performed on a MOM 1500 D Q-derivatograph. The plot heat of transformation by DSCvs. DTA peak area is advanced as a calibration line for the approximate estimation of quantitative DTA effects. The substances studied will be certified as temperature standard reference materials for use in DTA and DSC.

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Zusammenfassung Acht von der ICTA als Temperaturstandard-Referenzmaterialien für DTA und DSC empfohlene und im Lande verfügbare Substanzen wurden untersucht: KNO₃,KClO₄, Ag₂SO₄, K₂Cr₂O₄, Quarz, K₂SO₄, BaCO₃ und SrCO₃. Der Gehalt der Substanzen an diesen Verbindungen wurde klassisch chemisch-analytisch bestimmt. Temperaturen und Enthalpien der polymorphen Umwandlungen wurden mit dem Gerät DSC 2 (Perkin-Elmer) bestimmt, DTA-Untersuchungen erfolgten mittels Derivatograph Q 1500 D (MOM). Eine Darstellung (Umwandlungsenthalpie aus DSC-Messung) über der DTA-peak-Flä-che wird als Eichgerade für die näherungsweise quantitative Bewertung der DTA-Effekte vorgeschlagen. Die genannten Substanzen sollen als Temperaturstandards für DTA und DSC geprüft werden.

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(-, -, , , , , ), . . -2 -, Q- 1500 . ( ) — . .

     

Feststoffanalytik mit Autoprobe-GFAAS

Summary A new graphite system has been developed for GFAAS combining the autoprobe technique and solid sampling analysis. Based on previous studies with D₂-background corrected solid sampling GFAAS it has been demonstrated that the determination of Pb, Cd, Zn, Mn and Cu in various matrices of mainly biological origin is possible and practicable by means of solid sampling autoprobe GFAAS. Accuracy and precision are comparable to known solid sampling GFAAS systems.

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Herrn Dr. A. Rosopulo gewidmet     

Analytical quality control by solid sampling graphite furnace atomic absorption spectrometry in the production of animal tissue reference materials: bovine liver, teeth, bone, muscle, blood and equine renal cortex

Summary The function of solid sampling graphite furnace atomic absorption spectrometry (SS-GFAAS) in the laboratory-internal preparation, production and standardization of several animal tissue reference materials is described. SS-GFAAS is successfully applied in the production of a bovine liver reference material with a low content of Pb and Cd. The lab-internal production of 5 bovine teeth and 2 bovine bone reference materials illustrates some of the basic problems entailed in the analysis of Pb in osseus matrices and in the production of the reference material itself. In the production of muscle tissue reference material focal or generalized calcification is a serious source of endogenous Pb contamination. This is shown, by way of example, in the calcification of the larval states of Taenia saginata (Cysticercus bovis) in the bovine muscle. Finally, as further examples of the application of SS-GFAAS, the lab-internal production of reference material from bovine blood and equine renal cortex is described.     

Influence of the gas phase on metallic reference electrodes used in work function measurements

Contact potential differences between electrodes of Pt, Au and Ta of different surface finishing were measured by the dynamic condenser method in propylene and oxygen. Propylene is irreversibly adsorbed, thus changing the work function. This renders the electrodes unsuitable as standard electrodes for work function measurements on catalysts in the atmosphere of hydrocarbons, but they may be used in adsorption studies on oxygen.

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Pt, Au Ta . , , . , .

     

The use of thermal analysis in medical science with special reference to nephroliths

The applications of thermal methods in medical science have been summarized, with special regard to kidney stones. Complex thermal analysis can be used successfully for examination of human and animal urinary calculi, bones, odontoliths biological tissues (proteins, skin, callus, nail) etc.

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Zusammenfassung Es wurden die Anwendungen der Thermoanalyse auf medizinischem Gebiet unter besonderer Berücksichtigung von Nierensteinen zusammenfassend behandelt. Komplexe thermoanalytische Methoden eignen sich zur Prüfung von menschlichen und tierischen Harnsteinen, Knochen, Zahnstein, biologischem Gewebe (Proteine, Haut, Nägel, usw.)

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Résumé Revue des applications des méthodes thermoanalytiques dans le domaine médical avec mention particulière pour les calculs rénaux. L'emploi des méthodes d'analyse thermique mixtes donnent de bons résultats pour l'examen des calculs rénaux animaux et humains, du tartre dentaire et des tissus biologiques (protéines, peau, ongles), etc.

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, . , (, , , ) .

     

Kinetics of triphenylphosphite ozonide consumption in reaction with triphenylphosphite

Kinetic regularities of triphenylphosphite ozonide reaction with triphenylphosphite have been studied at T=–75°C to –40°C. The rate of ozonide consumption is estimated as W=k₁[(C₆H₅O)₃P·O₃]+k₂[(C₆H₅O)₃P·O₃][(C₆H₅O)₃P], where k₁=(2.03±0.39)×10^–5s^–1(–50°C), 1gk₂=(3.82±0.33)–(6.61±0.32)/gq dm³/mol s and =2.303RT kcal/mol.

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–75°C –40°C . : W=k₁[(C₆H₅O)₃P·O₃]+k₂[(C₆H₅O)₃P·O₃][(C₆H₅O)₃P], k₁=(2,03±0,39)·10^–5–1(–50°C); 1g k₂=(3,82±0,33)–(6,61±0,32)/ /·, =2,303·RT /

     

An interlaboratory test for certification of potassium chloride as a certified reference material (CRM) for solution calorimetry

The enthalpy of solution of KCl in H₂O (12000 mol·mol^–1) at 298.15 K was measured in an interlaboratory test in the G.D.R. The test material was prepared in the ASMW laboratories. The purity found on the high-precision coulometric titration of chloride was 0.9999±0.0001 g·g^–1. The consensus value of the enthalpy of solution in the test was H _s ^298.15 =17.47±0.07 kJ·mol^–1. This result is in good agreement with experimental values from recognized international scientific laboratories. The test material is applicable as a CRM.

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Zusammenfassung Die Lösungsenthalpie von KCl in Wasser (Molverhältnis 12000) bei 298.15 K wurde in einem Vergleichstest in mehreren Laboratorien der DDR gemessen. Das Testmaterial wurde in den Laboratorien des ASMW hergestellt. Eine coulometrische Präzisionstitration des Chlorids ergab seine Reinheit zu (0.9999±0.0001 g/g. Der übereinstimmende Wert für die Lösungsenthalpie wurde in dem Test zu H _s ^298.15 =(17.47±0.07) kJ mol^–1 gefunden, in guter Übereinstimmung mit experimentellen Angabe aus internationalen Laboratorien. Nach Abschluss des Testes ist das Material als bestätigter Bezugsstandard verwendbar.

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2000 / ₂ 298.75 . . ASMW. , - , 0.9999±0.0001 ·^–1. , , H _S298.15=17.47±0.01 ·^–1, , . , CRM.

     

Molecular isotope exchange of14CO in surface carbonyl complexes of rhodium

Molecular isotope exchange of CO with¹⁴CO for Rh₆(CO)₁₆/Sn(II)–SiO₂, Rh₆(CO)₁₆/Al₂O₃, Rh(I)(CO)₂/Al₂O₃, Rh₄(CO)₁₂/Al₂O₃ carbonyl complexes of rhodium has been studied. Estimates of the activation energies and a mechanism of the CO exchange are suggested.

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, (Rh₆(CO)₁₆/Sn(II)–SiO₂, Rh₆(CO)₁₆/Al₂O₃, Rh^I(CO)₂/Al₂O₃, Rh₄(CO)₁₂/Al₂O₃), ¹⁴CO. CO .

     

Oxygen diffusion in Me2O?V2O5 melts

The anodic and cathodic polarization of a platinum electrode in K₂O–V₂O₅ melt have been studied. The dissolved oxygen is shown to be ionized. Diffusion coefficients of oxygen in K₂O–V₂O₅ and Na₂O–V₂O₅ melts at various temperatures and K/V ratios are presented.

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K₂O–V₂O₅. , . K₂O–V₂O₅, Na₂O–V₂O₅ K/V.

     

Scanning electron microscopic study of an industrial catalyst for ammonia synthesis

The surface topography and elemental composition of the near-surface layers of a reduced passivated catalyst for ammonia synthesis have been studied on a scanning electron microscope in the initial state and after high-temperature oxygen treatment as well as removal of the alkali promoter.

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CA-IB , .

     

Chemical and x-ray structural investigation of a new diterpene lactone betolide

A crystalline substance with the composition C₂₀H₂₄O₅ has been isolated from the roots of common betony. The spatial structure of this new diterpene lactone, betolide, has been established from the results of UV, IR, NMR, and¹³C NMR spectral and x-ray structural investigations — 13-formyl-14-hydroxy-(2-hydroxy-5-oxotetrahydrofuro) [3,4:11,12]-^8,10,12-podocarpane, the first representative of new tetracyclic diterpenes the lactone ring of which is formed with the participation of a hydroxyl of a geminal diol. The stability of a lactone ring of this type and a high reactivity of the semiacetal hydroxyl have been shown.Institute of Chemical Sciences, Kazakhstan SSR Academy of Sciences, Alma-Ata. Division of the Institute of Chemical Physics, USSR Academy of Sciences, Chernogolovka. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 811–817, November–December, 1987.     

Catalytic properties of V?Mo?O systems in acrolein oxidation

Catalytic properties of V–Mo–O systems have been studied in acrolein oxidation. When catalysts are activated in reaction mixtures at 673 K, then a solid solution of molybdenum oxides in reduced vanadium oxides is formed, which is responsible for deep oxidation. Also, several compounds are produced, which by their activity and selectivity to acrylic acid formation are arranged in the sequences VMo₃O₁₁VMo₂O_8+x>V₆Mo₄O₂₅, and VMo₃O₁₁>VMo₂O_8+xV₆Mo₄O₂₅, respectively.

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V–Mo–O . 673 K , , , : VMo₃O₁₁VMo₂O_8+x>V₆Mo₄O₂₅, : VMo₃O₁₁>VMo₂O_8+xV₆Mo₄O₂₅.

     

Thermal decomposition of hydrazinium monoperchlorate in the molten state

The thermal decomposition of hydrazinium monoperchlorate (HP-1) in the molten state has been investigated using differential thermal analysis, thermogravimetric analysis, a constant volume manometric technique and mass-spectrometry. The stoichiometry of the reaction can be represented by the equation: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + + 23.5 H₂OThe data seem to indicate that the mechanism, which involves an associated complex, remains unchanged from 140 to 190°. Consequently, impurities capable of forming associated complexes with the hydrazinium or the perchlorate ion desensitize the thermal decomposition of HP-1, the extent of desensitization being determined by the size, the charge and the concentration of the impurity.

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Zusammenfassung Die thermische Zersetzung von Hydrazin-monoperchlorat (HP-1) im geschmolzenen Zustand wurde unter Einsatz der Differentialthermoanalyse, der thermogravimetrischen Analyse, der manometrischen Methode mit konstrantem Volumen und der Maßenspektrometrie untersucht. Die Stöchiometrie der Reaktion kann durch folgender Gleichung dargestellt werden: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 20₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂ODie Angaben zeigen, dass der Mechanismus, in welchen ein assoziierter Komplex mit inbegriffen ist, im Temperaturenbereich von 140° bis 190° C unverändert bleibt. Folglich setzen Verunreinigungen, die mit dem Hydrazinoder dem Perchlorat-Ion assozüerte Komplexe zu bilden imstande sind, die Empfindlichkeit der thermischen Zersetzung von HP-1 herab, wobei das Ausmaß der Herabsetzung von der Grösse, der Ladung und der Konzentration der Verunreinigung abhängt.

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Résumé La décomposition thermique en milieu fondu du monoperchlorate d'hydrazinium (HP-1) a été étudiée par analyse thermique différentielle, thermogravimétrie, manométrie à volume constant et spectromètrie de masse. La réaction peut être représentée par l'équation suivante: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂OLes données semblent indiquer que le mécanisme mettant en jeu un complexe associé reste inaltéré dans l'intervalle de températures allant de 140 à 190°. Par conséquent, les impuretés qui pourraient former des complexes associés avec les ions hydrazinium ou perchlorate désensibilisent la décomposition thermique de HP-1, le taux de désensibilisation étant déterminé par la taille, la charge et la concentration de l'impureté.

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(-1), , , - -. : 20 N₂H₅ClO₄ 13 NH₄ClO₄ + 3.5 l₂ + 2 ₂ + 13 N₂ + 0.5 N₂O + 0.5 ₂ + 23.5 ₂ , , - , 140° 190°. , , - , -1, , .

     

Isoprene hydrogenation in the presence of cobalt pohosphine complexes

The influence of the type of phosphine on the yield of methylbutenes in isoprene hydrogenation with complex cobalt catalysts has been studied. The complex H₃Co[P(n-C₄H₉)₃]₃ has been identified by the NMR method in the catalytic system Co(C₅H₇O₂)₂+P(n-C₄H₉)₃+Al(C₂H₅)₃. A mechanism of isoprene hydrogenation is suggested.

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. Co(C₅H₇O₂)₂+P(n-C₄H₉)₃+Al(C₂H₅)₃ H₃Co[P(n-C₄H₉)₃]₃. .

     

Thermal decomposition of yttrium,lanthanum and lanthanide complexes of square acid in air atmosphere

The conditions of thermal decomposition of the Y, La and lanthanide complexes of square acid in air atmosphere have been studied. On heating, the complexes of Y, La, Ce(III), Pr(III), Nd, Sm, Eu(III), Gd, Tb(III) and Ho decompose in two steps. First, the hydrated complexes lose crystallization water to form anhydrous salts. The complexes of Dy and Er decompose in three steps; they are dehydrated in two steps to form anhydrous salts. The complexes of Tm, Yb and Lu are dehydrated in three steps; in two steps they lose water molecules to form octahydrates, which in the third step are dehydrated during decomposition. On heating, the anhydrous complexes of Y, Ce(III), Pr(III), Eu(III), Gd, Tb(III), Dy, Ho and Er and the octahydrated salts of Tm, Yb and Lu decompose directly to the oxides Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇. The anhydrous complexes of La, Nd and Sm decompose to Ln₂O₃ with intermediate formation of Ln₂O₂CO₃.

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Zusammenfassung Die thermische Zersetzung von Komplexen von Y, La und Lanthaniden mit Squaresäure in Luft wurde untersucht. Beim Erhitzen zerfallen die Komplexe von Y, La, Ce(III), Pr(III), Nd, Sm, Eu(III), Gd, Tb(III) und Ho in zwei Schritten. Die hydrierten Komplexe geben zuerst Wasser ab und bilden wasserfreie Salze. Die Komplexe von Dy und Er zerfallen in drei Schritten, wobei sie in zwei Schritten zu wasserfreien Salzen dehydriert werden. Die Komplexe von Tm, Yb und Lu werden in drei Schritten dehydriert. Sie geben in zwei Schritten einige Wassermoleküle ab, um Octahydrate zu bilden, die dann während des Zerfalles dehydriert werden. Die wasserfreien Komplexe von Y, Ce(III), Pr(III), Eu(III), Gd, Tb(III), Dy, Ho und Er sowie die Octahydratsalze von Tm, Yb, und Lu zerfallen beim Erhitzen direkt zu den Oxiden Ln₂O₃, CeO₂, Pr₆O₁₁ und Tb₄O₇. Die wasserfreien Komplexe von La, Nd und Sm zerfallen über das Zwischenprodukt Ln₂O₂CO₃ zu Ln₂O₃.

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, . , , , , , , , . , . . . , . , , . , , , , , , , , , , Ln₂O₃, CeO₂, Pr₆O₁₁ Tb₄O₇. , Ln₂O₃ Ln₂O₂CO₃.

     

Equilibres solide ⇄ liquide ⇆ vapeur du systeme binaire CoCl2-H2O

Résumé Les équilibres solide liquide vapeur du système binaire CoCl₂-H₂O sont étudiés dans le domaine de température 120–720. La pression de la solution saturée est mesurée entre 1 et 60 atm. et le diagramme de phases est établi.Deux composés intermédiaires: CoCl₂ · 2H₂O et CoCl₂ · H₂O sont observés; ils subissent une décomposition péritectique à 206 et 335.Un tri et un tétrahydrate n'ont pas été obtenus malgré une étude systématique faisant intervenir des mesures d'analyse thermique, de thermogravimétrie et d'ébulliométrie.L'enthalpie et l'entropie de fusion du chlorure de cobalt sont évaluées à partir de la pente de la courbe de liquidus.Les valeurs calculées de l'enthalpie de déshydration de CoCl₂ · 2H₂O et CoCl₂ · H₂O entre 1 et 60 bars sont respectivement de 17 et 16 Kcal. mole^–1.

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Solid liquid vapor equilibria of the binary system CoCl₂-H₂O are investigated in the temperature range 120–720. The pressure of saturated solutions is measured between 1 and 60 atm, and the phase-diagram is established.Two intermediate compounds, CoCl₂ · 2H₂O and CoCl₂ · H₂O, are observed; they undergo peritectic decomposition at 206 and 335.Tri- and tetrahydrate have not been detected in spite of systematic research involving thermal analysis, thermogravimetry and ebulliometry.The enthalpy and entropy of fusion of cobalt chloride are calculated from the slope of the liquidus curve.The calculated enthalpy of dehydration values of CoCl₂ · 2H₂O and CoCl₂ · H₂O between 1 and 60 atm are 17 and 16 Kcal · mole^–1, respectively.

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Zusammenfassung Die Gleichgewichte Festkörper Flüssigkeit Dampf des binären Systems CoCl₂-H₂O wurden im Temperaturbereich von 120 bis 720C untersucht. Der Druck der gesättigten Lösung wurde zwischen 1 und 60 Atm. gemessen und das Phasendiagramm aufgenommen.Zwei Intermediärverbindungen: CoCl₂ · 2H₂O und CoCl₂ · H₂O wurden beobachtet; diese zersetzen sich bei 206 und 335 peritektisch.Ein Tri- und ein Tetrahydrat wurden trotz systematischer Untersuchungen mittels thermoanalytischer, thermogravimetrischer und ebulliometrischer Messung nicht gefunden.Die Enthalpie und Entropie der Kobaltchloridschmelze wurden aus der Steigung der Liquiduskurve ermittelt.Die errechneten Werte der Dehydratierungsenthalpie betrugen für CoCl₂ · 2H ₂ O und CoCl₂ · H₂O zwischen 1 und 60 bar 17 bzw. 16 Kcal₂ mol^–1.

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l₂-₂ 120–720. 1 60 . . CoCl₂. 2₂ l₂ · ₂, 206 335. , , , . . l₂. 2₂ l₂. ₂ 1 60 ., , 17 16 . ^–1.

     

Discrimination of active sites for ethylene homologation and ethylene metathesis on molybdena silica catalyst

Active sites for ethylene homologation (3C₂H₄2C₃H₆) and ethylene metathesis (C₂H₄–¹²C₂+C₂H₄–¹³C₂2C₂H₄–¹³C₁) were discriminated by adding platinum to a reduced molybdena silica catalyst, and the former was presumed to be composed of several molybdenum species, while the latter was presumed to be composed of one molybdenum species.

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(3C₂H₄2C₃H₆) (C₂H₄–¹²C₂+C₂H₄–¹³C₂2C₂H₄–¹³C₁) . , , .

     

An IR study of the Ziegler system Co(acad)3/Mg(n-butyl)2 in THF

Applying IR spectroscopy for studying the Ziegler system Co(acac)₃/Mg(Bu)₂ (Bu=n-butyl) in tetrahydrofuran, it could be shown that the following reactions take place: reduction of cobalt (III), exchange of the acetylacetonate groups and their interaction with Mg(Bu)₂.

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Co(acac)₃/Mg(Bu)₂ (Bu=-) - , (III), Mg(Bu)₂.