Simultaneous determination of p-hydroxylated and dihydrodiol metabolites of phenytoin in urine by high-performance liquid chromatography

Accurate urinary measurements of the two major metabolites of phenytoin, 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) and 5-(3,4-dihydroxy-cyclohexa-1,5-dienyl)-5-phenylhydantoin (dihydrodiol, DHD), are necessary for pharmacokinetic and drug-interaction studies of this commonly used antiepileptic drug. We describe a simple, rapid, acid hydrolysis, with liquid-liquid extraction and simultaneous isocratic reversed-phase high-performance liquid chromatography of p-HPPH and 5-(m-hydroxyphenyl)-5-phenylhydantoin (m-HPPH) (hydrolytic end product of DHD). p-HPPH and m-HPPH were quantitated against their separate respective internal standards of alphenal and tolylbarb. The mobile phase consisted of water-dioxane-tetrahydrofuran (80:15:5, v/v/v) at 2 ml/min and at 50 degrees C, with detection at 225 nm. Baseline separation was achieved by use of a 16 cm x 3.9 mm Nova-Pak C18 column and total analysis time of 12 min. p-HPPH and m-HPPH concentrations ranged from 10 to 200 and from 2 to 30 micrograms/ml, respectively, with between-day coefficients of variations of 3.3-4.5% and 2.2-5.1% for controls. All standard curves were linear with r values greater than 0.993. The DHD concentration was determined by multiplying m-HPPH concentrations by 2.3.     

Gallium-, Indium-Mangan- und Thallium-Rhenium-Carbonylverbindungen

Gallium-, Indium-Manganese-, and Thallium-Rhenium Carbonyl Compounds Compounds of type Na{Cl_4?nM[Mn(CO)₅]_n} (M ? Ga, In; n = 1, 2, 3) were prepared by reaction of the Lewis acids MCl₃ and NaMn(CO)₅. Instead of the sodium salts were obtained the compounds (C₃H₇CO₂)₂InMn(CO)₄L (Indium atom with the coordination number 5) from Indium(III) butyrate with two carboxylate groups bonded as chelate ligands and NaMn(CO)₄L [L ? CO, P(C₆H₅)₃] in the molar ratio 1:1. By reacting TlCl with NaRe(CO)₅ i.r. spectroscopic measurements of the solution pointed out the intermediate product TlRe(CO)₅, which was unstable against a disproportionation reaction into Tl and Tl[Re(CO)₅]₃. The last named compound delivered as a thermal decomposition product Re₂(CO)₈[μ-TlRe(CO)₅]₂. I.r. bands of the new compounds were assigned.     

Degradation of aromatic compounds in ground-water, and methods of sample preservation

The degradation of acenaphthylene, acenaphthene, 2-methylnaphthalene, 2-methylindene, 3-methylindene and indene in water solutions was studied. These compounds at the 25-150 mug/l. level were almost totally degraded at ambient temperature within three days. The microbial population responsible for the degradation occurs naturally in ground-water taken from an aquifer in Ames, Iowa, which is contaminated with coal-tar products. These unidentified micro-organisms adapt readily to other waters when used as an inoculant for the degradation of aromatic compounds. The preservation of water to prevent such degradation was also investigated. Filtration through a 0.45-mum filter was found the most effective procedure for preserving the hydrocarbons in these waters.     

Thermally induced ortho-metalation of dicarbomethoxyacetylenebis(triphenylphosphine)platinum

Heating a toluene solution of dicarhomethoxyacetylenebis(triphenylphosphine)platinum(0) at 130°C gives the ortho-metalated complex (Ph₃P)(Ph₂$\text{PC}{}_6\text{H}{}_4\text{)P}$t-trans-(COOMe)CCHCOOMe.     

Einige Aspekte der Quantitativen Röntgenemissionsanalyse Leichter Elemente bei Anregung Mit Schweren Teilchen

The aim of the paper is the simplification of calibration procedures in the investigation of multi-element-systems by calculating calibration curves. This requires, as well as taking into account the measuring geometry and the detector properties, above all the calculation of the number of the characteristic X-rays emitted by the sample per incident particle. For the calculation of the thick target yield a computer programme has been developed which makes possible a simple exchange of subroutines describing the stopping power of the sample, the cross-section of K-shell ionization, the fluorescence yield and the matrix absorption for the resulting K-X-rays of the elements contained in the sample. The agreement between experiment and calculation is discussed, when various approximations for the functions mentioned are used, as well as the possible influence of the grain size and surface roughness of the samples on the measurements, on which the calculations are based.      

Template chromatography on immobilized oligonucleotides. Synthesis and application of oligodeoxyadenosine-5'-phosphate--DEAE-cellulose (author's transl)]

Oligomers of deoxyadenylic acid, obtained by polycondensation, were covalently attached to polyvinyl alcohol. These polymer-bound oligonucleotides undergo very strong adsorption on DEAE-cellulose such that at neutral pH and with 1 M NaCl, partial desorbtion occurs only above 60 degrees. The use of this PV(pA)n-DEAE-cellulose for the column chromatographic separation of deoxythymidylic acid oligomers obtained by polycondensation, according to the principle of base-pairing, is discussed. Linear oligomers and also pyrophosphate derivatives of thymidylic acid which contain more than five monomer units undergo strong retardation under the conditions of base-pairing. Cyclic oligonucleotides do not show any noticeable interaction with the stationary phase. Thus, through the use of a temperature gradient, it is possible to fractionally separate the polycondensate, giving an average degree of polymerisation of 6--10.     

Delocalization resonance energy of the allylic radical from the geometrical isomerization of hexa-1,3,5-trienes

Thermal cis, trans geometrical isomerization theoretically involves a 90° twisted, singlet diradical-like transition state which may serve as a base for the examination of structural perturbations. Although thermal rearrangement of hexa-1, trans-3,5-triene (and all-trans octa-2,4,6-triene) to the cis isomer cannot be followed directly owing to subsequent cyclization and 1,5 hydrogen shifts, activation parameters for disappearance have been determined. Experimental complications and mechanistic uncertainties which make interpretation difficult are removed in the bicyclic hexatriene, cyclopentenylidenecyclopentene. These geometrical isomers undergo uncomplicated thermal cis, trans isomerization in vessels of lead-potash glass: log k₁ = 12·03±0·32?41·7±0·8/(0·004575T_abs). Extraction of a value for allylic delocalization energy from the behavior of hexa-1, trans-3,5-triene [log k₁ = 12·91 ± 0·47?44·3±1·2/(0·004575 T_abs)] requires corrections of the Dewar-Schmeising type for changes in hybridization of the σ bonds. Depending on whether ethylene or trans-butene is taken as standard, values of 12·2 and 13·1 kcal/mol are obtained (estimated uncertainty ± 2 kcal/mol).     

Esr spectra and magnetic constants of α-Al2O3:Co,H

ESR spectra of the defect α-Al₂O₃:Co²⁺, H⁺ are reported and used to derive the magnetic tensors g and A. This defect is shown to exist in several types, and models in the framework of the α-Al₂O₃ structures are proposed.     

Zur Oxydation von Tiron mit Wasserstoffperoxid in Gegenwart von Kobalt

Zusammenfassung Die Kinetik und der Mechanismus der von Kobaltionen katalysierten Tiron-Wasserstoffperoxid-Reaktion werden untersucht. Bei der Oxydation des Tirons bildet sich ein farbloses Produkt unbekannter Struktur, dessen Konzentrationszunahme zur photometrischen Messung der Reaktionsgeschwindigkeit dient. Unter den gewählten Bedingungen (3,56 · 10^–4 M Tiron, 0,1 M Wasserstoffperoxid, pH 10,3) verläuft die Reaktion bezüglich der Tiron- und Katalysatorkonzentration nach der 1. Ordnung. Die katalytische Reaktion, deren Geschwindigkeitskonstante zu 4,7 · 10⁴ l Mol^–1 · s^–1 ermittelt wurde, kann zur Kobaltbestimmung im Bereich von 0,6–10 ng/ml verwendet werden.Die Ergebnisse der Untersuchungen über die Oxydationsgeschwindigkeit des Tirons und über die Zersetzungsgeschwindigkeit des Wasserstoffperoxids in Abhängigkeit vom pH-Wert deuten darauf hin, daß die Zersetzung des Wasserstoffperoxids Voraussetzung für die Oxydation des Tirons ist. Während Tiron selbst eine stabilisierende Wirkung auf das Oxydationsmittel ausübt, katalysiert ein in Gegenwart von Kobaltionen entstehender Komplex dessen Zersetzung.

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Summary The kinetics and the mechanism of the tiron-hydrogen peroxide reaction catalysed by cobalt ions are investigated. The oxidation of tiron results in a product of unknown structure, whose increase of concentration is utilized for photometric reaction rate measurements. On the conditions used (3.56 · 10^–4 M tiron, 0.1 M hydrogen peroxide, pH 10.3) the reaction is of the first order with respect to tiron and catalyst concentration. The catalytic reaction, the rate constant of which was evaluated to be 4.7 · 10⁴ l · Mol^–1 · s^–1, can be used for the determination of cobalt in the range from 0.6 to 10 ng/ml.The results of the investigations on the oxidation rate of tiron and on the decomposition rate of hydrogen peroxide in dependence on pH indicate that the decomposition of hydrogen peroxide is a prerequisite for the oxidation of tiron. Whereas tiron itself shows a stabilizing effect on the oxidant, the complex formed in presence of cobalt ions catalyses the decomposition of hydrogen peroxide.

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Frau M. Borrmann gilt unser Dank für experimentelle Mitarbeit.     

Eine kühlzange als hilfsgerät im mikrolaboratorium

Zusammenfassung Eine thermoelektrische Kühlvorrichtung wurde beschrieben, die als Zange um Verbrennungsrohre geklemmt die Verflüchtigung von Probesubstanzen vor der Verbrennung besser als Kühlung mit Trockeneis hintanhält.

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Summary A thermoelectric cooling device is described. Clipped on combustion tubes, the volatilization of samples prior combustion is more effectively prevented than by dry-ice cooling.

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Herrn Univ.-Prof. DDr.Th. Leipert zum 65. Geburtstag gewidmet.

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Bezugsquelle: Fa. Apparatetechnik Ing. K. Lasser, Graz, Stiftingtal-straße 118.