Extractive spectrophotometric determination of dioxouranium(VI) with the sodium salt of hexamethyleneiminecarbodithioate

The optimum conditions for the extractive spectrophotometric determination of dioxouranium(VI) with hexamethyleneiminecarbodithioate(HMICdt) have been established. Dioxouranium(VI) reacts with this ligand at pH 4.5 to form a yellowish-orange uncharged 12 metal-ligand complex which can be extracted by chloroform. The calibration graph was linear in the range of 1–20 g ml^–1 of dioxouranium(VI) at 335 nm. The molar absorptivity of the extracted species is 5.952×10³ l mol^–1 cm^–1 with Sandell's sensitivity of 0.04 g cm^–2. The average of 10 determinations of dioxouranium was 49.75 g for the samples containing 50 g of U(VI) and the variation from the mean at 95% confidence limit was 49.75±0.5955.     

Effect of Surfactants on the Immobilization of 4-(2-Pyridylazo)resorcinol on Silochroms

The effect of cationic surfactants (cetyltrimethylammonium bromide, cetylpyridinium bromide, and tetrabutylammonium perchlorate) and a nonionic surfactant (OP-7) on the conditions of the immobilization of 4-(2-pyridylazo)resorcinol (PAR) on three types of silica gel (Silochrom S-120 (200–350 m), Silochrom S-120 (315–500 m), and Silochrom S-80 (200–350 m)) was studied. It was found that OP-7 does not affect the adsorption of surfactants. The effect of cationic surfactants increases in the order tetrabutylammonium perchlorate < cetyltrimethylammonium bromide < cetylpyridinium bromide. The adsorption activity of silica gels increases in the order Silochrom S-120 (315–500 m) < Silochrom S-80 (200–350 m) < Silochrom S-120 (200–350 m). Cetylpyridinium bromide provides full immobilization of PAR on silica gel Silochrom S-120 (200–350 m) in the pH range 2–9.     

Diacetylenic Derivatives of Fe2(CO)6(μ-EE′): Spectroscopic Investigations of Fe2(CO)6{μ-EC(H) = C(C≡ CMe)E′} (E = E′, E ≠ E′; E, E′ = S, Se, Te)

The diacetylenic adducts, Fe₂(CO)₆{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe₂(CO)₆(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (¹H, ¹³C, ⁷⁷Se, and ^l25Te) spectroscopy. Trends in the chemical shifts of ⁷⁷Se and ¹²⁵Te NMR spectra of Fe₂(CO)₆{-EC(H) = C(C CMe)E} with a variation of EE are discussed.     

Separation of linear gramicidins using carbon dioxide-containing mobile phases

Packed-column supercritical-fluid chromatography (pSFC) is presented as a novel method for separating and analyzing gramicidin samples. By use of methanol-modified carbon dioxide as a mobile phase the pentadecapeptides gramicidin A (gA), gramicidin B (gB), and gramicidin C (gC) are readily separated and eluted from a PRP-1 poly(styrene–divinylbenzene) column. Although optimum separation conditions are typically achieved near a column temperature of 40°C, a column pressure of 11 MPa, and 30% methanol modifier, pressure and modifier gradients around these values are also found to improve the overall separation time. Measurements indicate that the mobile phase solubility of gramicidin under these conditions is 5.0±0.4 g mL^–1. Collection of individual peaks during chromatography achieved analytical-scale isolation of 2 g refined gC from 20 g injected gramicidin D. Further, supercritical-fluid extraction of 200 g gramicidin D from a Chromosorb 102 support packed into the vessel produced 57 g gA in 90% purity. The results establish that carbon dioxide-based mobile phases can be successfully used for the separation of individual gramicidin species.     

Trace characterization of high-purity nickel by instrumental and radiochemical neutron activation analysis

Summary The high activity of the radionuclides ⁶⁵Ni (t_1/2=2.52 h) and ⁵⁸Co (t_1/2=70.8 d) imposes severe limitations on the performance of direct instrumental neutron activation analysis of nickel. The extent of the interference of the ⁵⁸Co depends on the ratio of the fluxes of the fast and thermal neutrons. A method of selective removal of cobalt, based on extraction with -nitroso--naphthol has been developed for the purpose of radiochemical NAA. Separation yields have been determined for 36 elements. The detection limits obtainable with both the instrumental and the radiochemical method are <10^–4 g/g for the elements Au, Eu, Ir, La, Sc and Sm, between 10^–4 and 10^–3 g/g for Cr, Cs, Hf, Hg, Lu, Re, Sb, Ta, Th, Tm and Yb, between 10^–3 and 10^–2 g/g for As, Ag, Br, Ce, Ga, Na, Ru, Se, W and Zn, and in the range 0.01–1 g/g for Ba, Cd, Co, Fe, In, K, Mo, Nd, Pd, Rb, Sn, U and Zr.     

Analysis of the fusariotoxins zearalenone and vomitoxin (deoxynivalenol) in human foods and animal feeds by high-performance liquid chromatography (HPLC)

Summary HPLC procedures for analyses of the fusariotoxins zearalenone and vomitoxin in individual food- and feedstuffs as well as in mixed feed are described. Zearalenone is separated on a column with polar stationary phase (25 cm × 4.6 mm i.d., particle size 7 m), eluted with a chloroform-isooctane (75/25, v/v)+1.5% methanol mixture and detected fluorometrically. The quantitative determination was possible in all analyzed samples with a detection limit of 2g/kg with 70–80% recovery. Vomitoxin is fractionated by HPLC (C ₁₈ ¹ column, 25 cm×4 mm i.d., 5 m particle size) with water-methanol (60/40, v/v) mobile phase and determined by combining GLC or TLC with UV detection. The detection limit in mixed feed with interfering substances was 25 g/kg (recovery 25–35%). The separation by HPLC makes preparation of pure vomitoxin possible. The described methods are fast, simple and low cost and are suitable for routine analyses.     

Simultaneous determination of arsenic and selenium in biological samples by HG-AFS

A new method is proposed for simultaneous determination of traces of arsenic (As) and selenium (Se) in biological samples by hydride-generation double-channel non-dispersive atomic-fluorescence spectrometry (HG-AFS) from tartaric acid media. The effects of analytical conditions on fluorescence signal intensity were investigated and optimized. Interferences from coexisting ions were evaluated. Under optimum conditions linear response ranges above 20 g L^–1 for As and 32 g L^–1 for Se were obtained with detection limits of 0.13 and 0.12 g L^–1, respectively. The precision for elevenfold determination of As at the 4 g L^–1 level and of Se at the 8 g L^–1 level were 2.7 and 1.9% (RSD), respectively. Recoveries of 92.5–95.5% for As and 101.2–108.4% for Se were obtained for four biological samples and two certified biological reference materials. The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for simultaneous determination of As and Se in biological samples.     

Simultaneous determination of copper,mercury and lead by first-order derivative spectrophotometry using dithizone as reagent

A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at g/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the ranges 0.5–10 (Cu), 1–10 (Hg) and 1–10 (Pb) g present in 40 ml of aqueous phase with detection limits of 5 g/L (Cu) and 20 g/L (Hg and Pb). The R.S.D.s for 100 g/L of copper, mercury and lead were 2.5, 2.6 and 3.1% respectively, for 5 determinations. The method is applicable for the determination of copper and lead in marine sediment samples with good precision and accuracy.     

Fällungsanalyse im Mikrogrammbereich: Eine neue Methode

Zusammenfassung Eine neue Methode zur Durchführung gravimetrischer Bestimmungen im Mikrogrammbereich wurde beschrieben; diese beruht im wesentlichen darauf, daß der Niederschlag nicht mehr zusammen mit dem Filter, sondern nach Überführen mit einem geeigneten Lösungsmittel in einem separaten Wägegefäß gewogen wird.Die dazu nötigen Geräte und deren Herstellung wurden beschrieben. Nach dieser Methode wurden folgende Bestimmungen mit zufriedenstellender Richtigkeit durchgeführt: 2,5–25g Al, 5–50g Cu und 5–50g Zn mit Oxin, 2,5–25g Fe(III) und 2,5–25g Ti(IV) mit N-Benzoyl-phenylhydroxylamin, 5–50g Ni und 5–50g Cu mit Salicylaldoxim, 2,5–50g Co(II) und 2,5–50g Fe(III) mit -Nitroso--naphthol sowie 5–50g Chlorid als Silberchlorid.

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Precipitation analysis in the microgram-scale: A new method

Summary A new method for gravimetric determinations in the microgram-scale is described. This method is based on the fact that the precipitate is not weighed together with the filter but is transferred to a separate weighingvessel using a suitable solvent. The necessary simple devices and their use are described. The following determinations were carried out with satisfying accuracy: 2,5–25g Al, 5–50g Cu and 5–50g Zn with Oxine, 2,5–25g Fe and 2,5–25g Ti withN-benzoylphenylhydroxylamine, 5–50g Ni and 5–50g Cu with salicylaldoxime, 2,52–50g Co and 2,5–50g Fe with -nitroso--naphthol and 5–50g chloride as silver chloride.

     

Determination of pentachlorophenol residues in wine and corks by solvent extraction methodology and specific gas chromatography detection

Summary A gas chromatographic methodology with selective detection is presented for the analysis in wines and corks of pentachlorophenol residues, which are suspected to be the most likely precursors of some off-flavours described in several wine samples. After derivatisation, pentachlorophenol acetate residues were monitored by electrolytic conductivity detection and/or mass spectrometric detection in the selective ion mode at m/z 264 and 266. Recoveries varied from 80 to 96% for wine samples fortified with 5 to 100 g l^–1 and from 83 to 91% for corks (fortified at 25 to 100 g kg^–1). The proposed methodology allowed for a determination limit of g l^–1 for wine and 10 g kg^–1 for corks.     

Characterization of airborne particulates by laser microprobe mass analysis

Summary Laser microprobe mass analysis (LAMMA) was applied to characterize aerosol particles collected and separated from 16m to 0.06m by a low pressure cascade impactor. Positive ion LAMMA spectra showed characteristic molecular peaks such as PbCl⁺, a series of Si₂O⁺–Si₂O₄ ⁺ and NaAl₂Si₂O₂ ⁺–NaAl₂Si₂O₅ ⁺, and TiO⁺ in 0.06–0.12m, 0.5–1m and 4–8m fraction, respectively. In the negative ion LAMMA spectra, it was observed that the fragment peaks of sulfate ions were deficient above 2m and those of nitrate ions were deficient under 2m. LAMMA allows remarkable insights into the chemical nature of aerosol particles.

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Charakterisierung luftgetragener Teilchen durch Laser-Microprobe-Massenspektrometrie

Zusammenfassung Laser-Microprobe-Spektrometrie (LAMMS) wurde zur Analyse atmosphärischen Aerosols herangezogen, welches im Korngrößenbereich zwischen 16m und 0.06m mit einem Niederdruckkaskadenimpaktor fraktioniert gesammelt wurde. Positive LAMMS-Spektren zeigten charakteristische molekulare Peaks, wie etwa PbCl⁺, eine Serie von Si₂O⁺–Si₂O₄ ⁺ und NaAl₂Si₂O₂ ⁺–NaAl₂Si₂O₅ ⁺, sowie TiO⁺ in der 0,06–0,12-m,- 0,5–1–m- bzw. 4–8-m-Fraktion. In den negativen LAMMS-Spektren konnten über 2m keine Fragmentpeaks für Sulfationen, unter 2m. keine für Nitrationen beobachtet werden. LAMMS ermöglicht eine bemerkenswerte Einsicht in die chemische Natur von Aerosolteilchen.

     

Acid-base properties of phosphoryl compounds 14. Hydrogen-bond polarity in complex phosphoryl compounds

Conclusions Dipole moments have been measured for phosphoryl compound complexes with alcohols and substituted phenols. A scheme for calculating the H-bond polarity (_h) in these systems is discussed; the value of _H can be described in terms of a charge transfer model.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2288–2292, October, 1978.The authors wish to thank B. A. Kvasov for his help with the measurements on the NMR spectra.     

The composition of volatile and particulate hydrocarbons in urban air

Summary The hydrocarbon composition of the particle and gas phases in the urban atmosphere has been studied by filtration and parallel adsorption on active charcoal and polyurethane foam (PUF). Gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS) have been used for the analysis of the organic matter extracts obtained with each system. In the case of the particle and PUF samples these extracts were fractionated into aliphatic and aromatic compounds. This approach has allowed to identify up to 247 hydrocarbon molecules showing that C0–C5 alkylbenzenes are the major compounds in the charcoal extracts whereas C14–C23 n-alkanes, C0–C4 alkylnaphthalenes, C0–C4 alkylbiphenyls and C3–C5 alkylbenzenes are those predominantly found in the PUF materials. The particles essentially contain C17–C38 n-alkanes and parent polycyclic aromatic hydrocarbons (PAH). These qualitative differences are paralleled by a progressive concentration decrease from the more to the less volatile hydrocarbons. Thus, the total charcoal extracts average 80 g/m³, the PUF compounds represent 4 /m³ and the particle hydrocarbons 0.7 g/m³. These latter airborne materials are essentially composed of petrogenic residues 0.6 g/m³ (aliphatic fraction) whereas the pyrolytic PAH only involve 0.08 g/m³.     

Bestimmung des Metabolismus und der Produktionsrate von Testosteron, Dehydroepiandrosteron und Dehydroepiandrosteronsulfat

Zusammenfassung Nach i.v. Injektion von 4–6 Ci¹⁴C-Testosteron und 7–8 Ci³H-Androstendion oder entsprechenden Mengen¹⁴C-Dehydroepiandrosteron und³H-Dehydroepiandrosteronsulfat wurden die Glucuronide von Testosteron, Androsteron, Ätiocholanolon und Dehydroepiandrosteron sowie Dehydroepiandrosteronsulfat säulen- (Al₂O₃), papier- (Bush A₂) und dünnschicht-chromatographisch (Chloroform/Äthylacetat 41) aus Urin abgetrennt und gas-chromatographisch (1% XE-60, Flammenionisationsdetektor) bestimmt. Nach splitting des Trägergases und Kondensation der gasförmigen Steroide in einem wattegefüllten Glasröhrchen eines Gasfraktionskollektors wurde die¹⁴C- und³H-Aktivität der einzelnen Androgenmetaboliten mit einem Müssigkeitsszintillationszähler gemessen und aus der spezifischen Aktivität (Impulse/Mikrogramm) die Produktions- und Interkonversionsraten von Testosteron, DHEA und DHEA-Sulfat berechnet.

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Determination of the metabolism and production rates androstendione of testosterone, dehydroepiandrosterone, and dehydroepiandrosterone sulphate

After the i.v. application of 4–6 Ci¹⁴C-testosterone and 7–8 Ci³H-androstendione or equivalent dosages of tritium dehydroepiandrosterone sulphate and dehydroepiandrosterone the gluouronides of testosterone, etiocholanolone, androsterone and dehydroepiandrosterone and dehydroepiandrosterone sulphate were separated from urine by column (Al₂O₃), paper (system Bush A₂) and thin-layer (chloroform:ethylacetate=41) chromatography. After a final gas-liquid chromatography on 1% XE-60 the androgen metabolites were estimated quantitatively by flame-ionisation detector. The radioactivity (³H and¹⁴C impulses) of the compounds was measured after splitting the carrier gas and condensation of the steroids in a gas-fraction collector. From the specific activity (Imp/g) the production and interconversion rates of testosterone, dehydroepiandrosterone and dehydroepiandrosterone sulphate were calculated.

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Die Arbeit wurde mit Mitteln des Bundesministeriums für Wissenschaftliche Forschung gefördert.     

Enzymatische Mikrobestimmung basischer Aminos?uren

Zusammenfassung Eine Apparatur und Arbeitstechniken zur konduktometrischen Bestimmung von Kohlendioxidmengen im Bereich von 1–20 g werden beschrieben. Die Standardabweichung der Bestimmung beträgt etwa 0,3 g CO₂. Bei Verwendung entsprechender Decarboxylasen können Arginin, Histidin und Lysin im gleichen Konzentrationsbereich mit einer Standardabweichung von etwa 1 g bestimmt werden.

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Summary An apparatus and techniques for the conductometric determination of carbon dioxide in amounts from 1 to 20 g are described. The standard deviation of the determination is about 0.3 gmg of CO₂. Arginine, histidine and lysine can be determined in the same range of concentration with a standard deviation of about 1 g after enzymatic decarboxylation.

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Der Verband der Chemischen Industrie unterstützte die Untersuchungen in dankenswerter Weise durch Sachspenden (Operationsverstärker, Programmkartengeber).

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Herrn Prof. Dr. W. Geilmann zum 75. Geburtstag gewidmet.     

Elements in car and truck tires and their volatilization upon incineration

The trace metal loading of used car and truck tires and the fractions of the metals volatilized upon incineration of the tire were determined. INAA was chosen due to its multielement analysis capability and its low detection limit for many elements. A high purity planar germanium detector was used. Among the elements measured were, Al (4–150 g/g), Ti (41–730 g/g), V (0.04–0.4g/g), Mg (>80–580 g/g), Zn (1–2.2%) as typical concentrations; also some amounts of antimony, bromine and arsenic have been found. Major differences in elemental concentrations have been observed between the tread and the wall of a tire, and also between different brands.     

LC Method for the Determination of Multiple Components in a Compound Cold Formulation

An isocratic liquid chromatographic method for determination of acetaminophen (AMP), caffeine (CAF), chlorphenamine maleate (CPM) and guaiacol glyceryl ether (GGE) in a compound cold formulation is described. Separation and quantitation were achieved on a Diamonsil C18 column using a binary mixture of methanol and 1.5% aqueous acetic acid (55: 45, v/v, pH 3.6) as mobile phase delivered at 0.4 mL min^–1. Single wavelength detection was at 220 nm for all four drugs and the run time was < 10 min. The linearity, accuracy and precision of the method were found to be acceptable over the concentration ranges: 16.0–127.8 g mL^–1 for AMP, 6.0–48.2 g mL^–1 for CAF, 5.0–40.0 g mL^–1 for CPM and 10.1–80.6 g mL^–1 for GGE.     

Flow injection analysis at μl/min flow rates

The characteristics of knitted open tube (KOT) figure eight reactors and coil reactors at l/min flow rates were compared using plate height (H) calculations and peak height measurements. Peak broadening independent of flow rate was seen for the figure eight KOT but not the coil at flow rates of 150–300 l/min. Below 150 /min, the plate height values of both reactors were inversely proportional to flow rate. It was concluded that a 0.5-m KOT figure eight reactor is the most effective way to introduce delay time for a 1 1 injection size and tubing of 0.3 mm I.D. Enhancement of peak height response was particularly pronounced at flow rates less than 100 l/min.