Kurze Originalarbeiten: Zur Reindarstellung von tritiummarkierten Pyrimidinderivaten 1. Mitt. Markierung von 5-Hydroxyuracil und 5-Aminouracil durch katalytischen II-T-Austausch

Zur Vervollkommung der strahlenchemischen Technologie für die Herstellung einiger für die Industrie wichtiger silizium-organischer Monomere und zur Durchführung von Forschungs-arbeiten auf diesem Gebiet wurde eine Pilot-Anlage unter Verwendung des Elektronenbeschleunigers EU-0,4 geschaffen, der im Physikalisch-chemischen Forschungsinstitut ?L. J. Karpow“ auf der Grundlago des Rōntgendefektoskopie-Gerātes RUP-400-5 entwickelt wurde.     

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Es wird über eine spezifische Abtrennung des Urans aus Mischungen radioaktiver Spaltprodukte mittels Dünnschichtchromatographie berichtet. Die bei kurz bestrahlten Uranproben am Uranfleck gefundene Radioaktivität kann auf Grund γ-spektrometrischer Messungen dem ²³⁹Np zugeordnet werden.     

2. Mitteilung: Tetraphenylarsoniumverbindungen und Pentaphenylarsen

Es wurde ein Trennverfahren ausgeabeitet, das es gestattet, die Aktivitätsausbeuten für Mono-, Di- und Triphenylarsenverbindungen, für Tetraphenylarsoniumverbindungen und für Pentaphenylarsen sowie für nicht organisch gebundenes Arsen in neutronenbestrahlten Tetraphenylarsoniumver erbindungen und in Pentaphenylarsen zu bestimmen. Als Trennmethoden werden Extraktion, Ionenaustauwsch und Al₂O₃-Chromatographic benutzt. Zur Reinigung und Ausbeutebestimmung von Di- und Triphenylarsenprodukten sowie von Tetraphenylarsonimverbindungen finden Kristallisations- bzw. Fällungsreaktionen Anwendung unter Ausnutzung des Prinzips der Isotopenverdünnungsanalyse.     

Radiation-enhanced diffusion and fission gas release from recrystallised grains in high burn-up hbox{UO}_{2} nuclear fuel

The effective diffusion coefficient that gives a steady-state xenon concentration of 0.2-0.3wt% in the recrystallised grains of high burn-up UO 2 fuel is calculated to lie in the range 10 m 24 to 10 m 22 m 2 s m 1 . These values are one to three orders of magnitude lower than the value currently accepted for the radiation-enhanced diffusion coefficient. The time required to reach the steady-state concentration depends on the local fission rate, the grain size distribution and the precise magnitude of the radiation-enhanced diffusion coefficient, and can take from 2 to 10 years. Additional calculations reveal that substantially less than 10% of the fission gas inventory is released from the original UO 2 grains in the outer region of the fuel prior to recrystallisation. In contrast, with a diffusion coefficient of 10 m 22 m 2 s m 1 more than 80% of the fission gas is released from the recrystallised grains of the high burn-up structure in one year.     

Defect-related relaxation processes in irradiated rare gas solids

Electronic and atomic relaxation processes in preirradiated solid Ar doped with N 2 were studied with a focus on the role of radiative electronic transitions in relaxation cascades. Combining methods of activation spectroscopy - thermally stimulated and photon-stimulated exoelectron emission, a new channel of relaxation induced by photon emission from metastable N atoms was detected. It was shown that in insulating materials with a wide conduction band photons of visible range can release electrons from both kinds of traps - shallow (lattice defects) and deep thermally disconnected ones. Correlation in the charge recombination reaction yield and the yield of low temperature desorption - important relaxation channel in a preirradiated solid - clearly demonstrates interconnection between atomic and electronic processes of relaxation.     

Book reviews

This work is a thorough investigation on the major operating parameters of the programmable temperature vaporisation (PTV) inlet used for gas chromatographic injection, including injection mode and volume, inlet temperature, vent and purge flow rates. The results clearly demonstrate the advantage of large volume injection in enhancing the detection of polybrominated diphenyl ethers (PBDEs). Partial loss of injected PBDEs occurred during solvent venting and due to incomplete sample transfer. Such loss was minimised by lowering the initial inlet temperature and vent flow and elevating the final inlet temperature. The results show that 50 mL/min vent flow, as low as 0°C initial and higher than 300°C final inlet temperatures produced the relatively high responses. Two mass spectrometric parameters were also evaluated. Indoor dust, lake sediment and human placenta tissue samples were analysed to demonstrate reliability and sensitivity improvement of the PTV large volume injection.     

Solid-Phase Extraction and Capillary Gas Chromatographic Determination of Triazine Herbicides in Water

Abstract

A facile and efficient method is described for the determination of trace quantities of triazine herbicides, terbutryn, prometryn and ametryn in water. The procedure involved preconcentration of water samples by sorption on chromatographic grade silica gel particles with chemically modified surface, being covalently bonded with a nonofunctional C₈H₁₇ group. This was followed by solvent desorption with 2-propanol. The determinative step was achieved by capillary gas chromatography on Supelcowax-10 fused silica column using a nitrogen-phosphorus detector. The limit of detection was 0.1 μg-10 μgL^?1.     

Analysis of PCBs in Biotic Matrices by Two-Dimensional GC-ECD

Abstract

The suitability of three GC-ECD systems for the separation of a model mixture containing various congeners of PCBs together with persistent chlorinated aromatics (pesticides and their metabolites, industrial chemicals) was tested. Analyses were performed on two parallel capillaries, the stationary phase of one of them was always in routine practice very common 5% phenyl-methylpolysiloxane, the second one was either 50% phenylmethylpolysiloxane or 7% phenyl-7% cyanopropyl-methylpolysiloxane. The number of unresolved (coeluted) analytes was significantly reduced in these systems and thus unbiased quantitation of PCBs and other components used for regulation was possible. The utilization of this type of multidimensional chromatography for rapid and reliable analysis of real samples (fish oil, human fat) was documented.     

高效液相色谱法同时测定生物质乳酸发酵液中有机酸及糖类化合物

建立了高效液相色谱(HPLC)同时测定生物质乳酸发酵液中有机酸及糖类的分析方法。使用Bio-Rad Aminex HPX-87H色谱柱,以5 mmol/L的H2SO4为流动相,在柱温55 ℃,流速0.6 mL/min条件下,采用示差折光检测器进行检测。结果表明,该方法可在17 min内实现发酵液中各种有机酸和糖类化合物等的完全分离与定量,6种有机酸和3种糖类化合物在0.15～5.19 g/L范围内的线性关系良好,回归方程的线性相关系数在0.9998以上。将该法用于米根霉发酵液的检测,两个水平的加标回收率为96.91%～103.11%,相对标准偏差(n=6)为0.81%～4.61%。该法适用于微生物发酵液中多种有机酸和糖类的快速、高效分离和定量测定。     

A Photochemistry Technique Using Ultraviolet Irradiation Followed by Gas-Liquid Chromatography to Confirm the Identity of Some Organochlorine Pesticides

Abstract

A procedure involving ultraviolet (UV) irradiation followed by gas-liquid chromatographic (GLC) detection of photodecomposition products to confirm the identity of selected organochlorine pesticides is described. The Irradiation intensity was standardized by determining the position relative to the UV source which resulted in equal GLC peak heights for the parent compound and major photo-decomposition product after 8 minutes of exposure of a solution of heptachlor epoxide in isooctane. Chromatograms showing photo-decomposition patterns for 33 compounds are presented. Observations and comments on the applicability of this technique to organo-chlorine pesticide residue confirmation are reported.