Determination of low levels of an antioxidant in polyolefins by large-volume injection temperature-programmed packed capillary liquid chromatography

Sub-ambient column temperatures, promoting strong interactions between the analyte and the stationary phase material, were utilized to focus large volumes of the polyolefin antioxidant Irganox 1076 [benzenepropanoic acid, 3.5-bis(1,1-dimethylethyl)-4-hydroxy-, octadecyl ester] on the column inlet, using pure acetonitrile as sample solvent and mobile phase. Injection volumes up to 100 microl were successfully employed on a 50 cm x 320 microm I.D. capillary column packed with 5 microm Kromasil 100 ODS particles. Irganox 1076 was eluted after completed injection by temperature programming, using a temperature program from 7 to 90 degrees C, in 3 degrees C min(-1). UV detection, using a low-dispersion "U"-shaped flowcell, was performed at 280 nm. The method was applied for the determination of Irganox 1076 that was extracted from low-density polyethylene (0.6 ppm, w/w). Both Soxhlet and microwave-aided solvent extractions were performed, using chloroform and acetonitrile as solvents, respectively. The microwave-aided extraction with acetonitrile was found to give approximately the same yield as the standard Soxhlet reference method. Consequently, small volumes of acetonitrile could be used both as extraction solvent, sample solvent and mobile phase, simplifying the analysis process. The mass limit of detection of the method was found to be 3.3 ng, corresponding to a concentration limit of detection of 33 ng ml(-1), utilizing an injection volume of 100 microl. The within and between day precision of retention times displayed relative standard deviations below 1.2%.     

Synthesis and stereochemistry of (−)-(10s)-6,10-dimethyl-6-aza-δ1,9-octahydroquinoline

Enantiomericalfy pure (–)-(10S)-6,10-dimethyl-6-am-^1,9-octahydroquinoline, which has been obtained from optically pure (3S)-1,3-dimethyl-3-(2-cyanoethyl)piperid-4-one, is a chiral intermediate for the preparation of novel biologically active compounds and an analog of piperidine and decahydroquinoline alkaloids. The chiroptical properties of the synthesized 6-azaoctahydroquinoline are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1379–1383, October, 1992.     

Thermal decompositions of sulphosalicylates of MG(II), CA(II) and ZN(II)

The thermal decompositions of the sulphosalicylates of Mg(II), Ca(II) and Zn(II) have been investigated by means of TG and DTA. The preparation and analysis of these compounds are included. The possible decomposition reactions in the various stages and the final decomposition products are discussed.     

Anomalies in the asymmetric hydroboration of olefins with the 11 adduct of (+)-α-pinene and BH3 · THF

The hydroboration of cis-2-butene and cis-3-hexene with pure diisopinocampheylborane (IPC₂BH) and monoisopinocampheylborane (IPCBH₂), both prepared from (+)-α-pinene, were studied. In contrast to IPC₂BH, which yielded R-(?)-2-butanol and R-(?)-3-hexanol in 98.4 and 94.5% optical purities, IPCBH₂ yielded S-(+)-2-butanol and S-(+)-3-hexanol in 23.6 and 19.7% optical purifies respectively. PMR examination of the methanolyzed products were utilized to establish the species present in the freshly prepared and aged $\text{1}\text{1}$ adduct from (+)-α-pinene and BH₃ · THF. The results confirm the interpretation previously advanced for the major differences realized in asymmetric hydroboration with the fresh and aged $\text{1}\text{1}$ adducts.     

Indolizine derivatives. IX. Preparation of 1-acylpyrrolo[2,1,5-cd]indolizines via cycloaddition of 3-acyloxyindolizines to active ethylenes and acetylenes

3-Indolizinyl acetates and propionates 4 react with ethylenic and acetylenic ketones or carboxylic esters to give 1-acylpyrrolo[2,1,5-cd]indolizines 5-12 in excellent yields.     

The structure of kesselringine

Summary On the basis of IR, PMR, and mass spectra and chemical transformations, the alkaloid kesselringine isolated from the epigeal parts ofColchicum kesselringii Rgl. has been shown to have the structure of 2,11-dihydroxy-12-methoxyhexahydro-1,12-epoxyhomoproaporphine with the R absolute configuration at the C_6a atom.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 350–354, May–June, 1976.     

Dynamics of the accumulation of the alkaloids ofReseda luteola structure of lutine and lutinine

Summary The biosynthesis of the alkaloids ofAmmothamnus lehmannii Bge. have been studied by supplying the plants with [1,5-¹⁴C₂] cadaverine. It has been shown that cadaverine is a precursor of sophocarpidine, sophocarpine, and pachycarpine. Possible routes of interconversions have been studied by supplying the plants with the tritium-labelled alkaloids [³H] sophocarpine, [³H] matrine, and [³H] pachycarpine.V. I. Lenin Tashkent State University. Institute of Plant Biochemistry, Academy of Sciences of the German Democratic Republic, Halle. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 776–780, November–December, 1976.     

Novel electroanalytical techniques for pollution analysis

Summary Two new analytical techniques are described. The so-called injection technique operates on evaluating a dynamic concentration signal as a result of following the concentration change in a certain part of a flow-through channel after injecting a sample or reagent at a small volume into the current of an appropriate solution flowing at a constant rate.The second technique, the programmed coulometric titration technique, also uses the flow-through channel principle; that means this novel technique allows the more precise titrimetric way of analysis in flowing solutions. In the case of both techniques potentiometric and voltammetric detectors were involved. Several examples proved the multifold advantages of these techniques for environmental analysis.

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Neue elektroanalytische Verfahren für die Umweltanalyse

Zusammenfassung Zwei neue Methoden werden beschrieben. Die sog. Injektionstechnik wertet ein dynamisches Konzentrationssignal aus, das sich aus der Änderung in einem Durchflußkanal ergibt, wenn Probe oder Reagens in kleinen Volumina in einen konstant fließenden Flüssigstrom injiziert werden. Das zweite Verfahren, die programmierte coulometrische Titration, erlaubt die Anwendung der genaueren titrimetrischen Technik auf fließende Lösungen. Bei beiden Methoden werden potentiometrische und voltammetrische Detektoren verwendet. Mehrere Beispiele zeigen die vielfachen Vorteile dieser Verfahren bei der Anwendung auf die Analyse von Umweltmaterial.

Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria     

Increased transport of theophylline into gastrointestinal lumen and gastrointestinal dialysis by activated charcoal in rats with hepatic cirrhosis

The characteristics of exsorption and/or excretion of theophylline into the small intestinal lumen in rats with hepatic cirrhosis (HC rats) induced by carbon tetrachloride were investigated by an in situ single-pass perfusion technique. The serum concentrations of theophylline after i.v. administration of aminophylline (10 mg/kg) in the HC rats were significantly higher than those in normal rats during the experimental period. Moreover, the exsorption of theophylline from blood into the intestinal lumen was significantly increased in the HC rats compared with the normal rats. Treatments with oral activated charcoal reduced the serum theophylline levels in the HC rats. Consequently, gastrointestinal dialysis by oral administration of activated charcoal may be a useful method to remove poisonous drugs from the blood in patients with hepatic failure (including cirrhosis), which decreases the systemic clearance.     

Substituenteneffekte auf azido-tetrazolo-gleichgewichte elektronische und sterische effekte bei s-triazolo[4,3-c]tetrazolo[1,5-a]pyrimidinen1

The azido tetrazolo valence isomerism of twenty 9-methyl-s-triazolo[4,3-c]tetrazolo[1,5-a]pyrimidines with different substituents at position 5 has been studied by means of ¹H NMR spectroscopy. All the compounds have been found to be tetrazoles in the solid state and in (CD₃)₂SO solution; in CF₃COOH azido and tetrazolo isomers are in equilibrium. From equilibrium constants K and thermodynamic data determined it is concluded that in this series K depends on both electronic effects and steric requirements of the 5-substituents. A linear relation between K and σ was found for 5-arylderivatives because ΔS° keeps approximately constant and the substituent mainly operates on ΔH°.