Polyazido high-nitrogen compounds: hydrazo- and azo-1,3,5-triazine.
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The characterisation and optimisation of an optical immunoassay with label free detection based on Reflectometric Interference Spectroscopy (RIfS) is presented. The immunoprobe is operated in a sequential scheme, where Fab-fragments react with analyte molecules in a first step. In a second step the optical transducer is used to quantify the amount of unoccupied Fab- fragments in the reaction mixture binding to the hapten-modified transducer surface. For optimisation of the test, the Fab-fragment concentration was varied between 2x10(-8) mol/l and 2.5x 10(-9) mol/l. Down to a concentration of 5x10(-9) mol/l a reduction in the limit of detection has been observed. At the lowest concentration investigated no further improvement has been found due to a reduced binding of the analyte and a strong decrease of antibody binding at the transducer surface. This finding could be explained by the thermodynamics of the antigen-antibody reaction and the performance of the optical transducer used. The limit of detection obtained is discussed with respect to thermodynamics, transducer characteristics and immunoprobe test format.
Gram quantities of homogeneous glycerokinase have been prepared from the thermophilic bacterium, Bacillus stearothermophilus, using three major steps: precipitation of debris at pH 5.1, ion-exchange chromatography on DEAE-Sephadex, and affinity chromatography on Procion Blue MX-3G-Sepharose. This method is a considerable improvement over conventional techniques; the purified enzyme was obtained with a 40% recovery and a specific activity of 120 units (mumol/min)/mg protein. A modified culture medium enabled yields of 3.4 X 10(6) units of enzyme to be obtained from 400-liter production cultures.
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The metabolism of 1-(4-acetylphenyl)-3,3-dimethyltriazene has been studied in vivo and in vitro in mice. This dimethyltriazene was extensively metabolised in vivo and HPLC analysis of the plasma revealed the presence of two metabolites, the monomethyltriazene, 1-(4-acetylphenyl)-3-methyltriazene, and the arylamine, 4-aminoacetophenone. The dimethyltriazene was also biotransformed in vitro by a 9000 g fraction of mouse liver homogenate to products which were selectively toxic to TLX5 lymphoma cells. HPLC analysis of the products of in vitro metabolism under these conditions showed the presence of the monomethyltriazene but in an amount insufficient to account for the observed cytotoxicity. The monomethyltriazene was itself rapidly biotransformed by a 9000 g fraction of mouse liver homogenate, and by isolated mouse hepatocytes.
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Daily s.c. injections of atrazine and deethylatrazine to rat mothers during pregnancy only or during pregnancy and lactation influenced the pituitary-gonadal axis of male and female offsprings. In female and male offspring, slow maturation of gonadotropic system is evident and as a consequence modified male and female pituitary 5 alpha-R activity is present. The number of specific steroid-hormone receptor sites at the offsprings' gonads is unchanged if the mothers were treated only during pregnancy, but 5 alpha-DHT prostate receptors are strongly inhibited in offspring of mothers treated with atrazine and deethylatrazine during pregnancy and lactation.
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A possibility of a combination of supported liquid membrane (SLM) and solid-phase extraction (SPE) for the determination of atrazine at microgram level in different type of fruit juices is presented. In comparison to SPE extraction from juice samples, the application of SLM-SPE enrichment provides much cleaner extracts and the possibility of lowering the limit of detection as low as 30 microg/l. However, it was also shown that by appropriate manipulation of SLM extraction conditions mainly flow-rate of donor phase and volume ratio between donor and acceptor phase, the level of detection can be further decreased to 10 microg/l. The results suggest that the application of SLM extraction prior to SPE is an alternative method for atrazine enrichment from complicated liquid matrices and could be used as routine method for the clean-up of such samples.
Deethylatrazine (DEA), an atrazine degradation product, has been added to the US Environmental Protection Agency's Drinking Water Contaminant Candidate List (CCL). In its gas chromatographic analysis, DEA can coelute with deisopropylatrazine (DIA), another degradation product. The present work demonstrates that the coelution of DEA and DIA can induce a significant (up to approximately 50%) positive bias in the DEA determination, when using an ion-trap mass spectrometer as the detector. The DIA determination is unaffected by the coelution within experimental error. This may be explained in terms of gas-phase ion fragment populations. A correction factor to the observed DEA concentration may be developed based on the measured DIA concentration.