2-arylimino-3-thiazolines - formation of unusual tautomers of 2-arylamino-thiazoles by a modified hantzsch synthesis

The reaction of thioureas with 3-bromomethyl-2-cyanocinnamonitrile gives the hydrobromides either of the 2-aminothiazoles or of the hitherto unknown 2-imino-3-thiazolines.     

N-(2,6-Dihalobenzoyl)-N′-pyrimidinylharnstoffe

N-(2,6-Dichlorobenzoyl)- and N-(2,6-difluorobenzoyl)-N-pyrimidinylureas3b–3n have been synthesized by reaction of the corresponding aminopyrimidine derivatives with 2,6-dichlorobenzoyl isocyanate or 2,6-difluorobenzoyl isocyanate. The insecticidal activity of compounds3b–3n has been evaluated.

     

Experimental design-based development and single laboratory validation of a capillary zone electrophoresis method for the determination of the artificial sweetener sucralose in food matrices

A capillary zone electrophoresis (CZE) method, optimised chemometrically, underwent a complete in-house validation protocol for the qualification and quantification of sucralose in various foodstuffs. Separation from matrix components was obtained in a dinitrobenzoic acid (3 mM)/sodium hydroxide (20 mM) background electrolyte with a pH of 12.1, a potential of 0.11 kV cm^–1 and a temperature of 22 °C. Detection was achieved at 238 nm by indirect UV. Screening, optimisation and robustness testing were all carried out with the aid of experimental design. Using standard addition calibration, the CZE method has been applied to still, carbonated and alcoholic beverages, yoghurts and hard-boiled candy. The method allows the detection of sucralose at >30 mg kg^–1, with a linearity range of 50–500 mg kg^–1, making it suitable for implementation of the recently amended Sweeteners for use in foodstuffs Directive (European Parliament and Council (2003) Off J L237:3–12), which set maximum usable doses of sucralose for many foodstuffs, most ranging from 200 mg kg^–1 to 450 mg kg^–1.     

Evaluation of the results from an inter-laboratory comparison study of the determination of acrylamide in crispbread and butter cookies

Analytical methods currently employed for determination of acrylamide (AA) in two carbohydrate-rich food samples, crispbread and butter cookies, obtained commercially, and native and spiked bread extract samples have been evaluated in a collaborative study. The objective of the study was to obtain information about the performance of the participating laboratories when analysing samples with an AA content close to the limit of quantification (LOQ) and at a higher AA level, and to investigate the influence of sample-preparation procedures on the results of the analysis. For this purpose an aqueous native extract of white bread crumb, a fortified extract, and AA standard solutions, the analyte content of which were not disclosed to the participants, were included in the study. A total of 62 laboratories, applying seven different measurement techniques and a broad spectrum of analyte extraction and sample-preparation procedures reported their analytical results. Because the measurement data were not normally distributed, they were evaluated by application of robust statistics. The relative performance of the laboratories was highlighted by calculation of z-scores. For the crispbread sample, especially, a large percentage of the calculated z-scores were outside the satisfactory range. From their distribution it became obvious that one of the analytical techniques might be biased, if not applied correctly. Consequently, the impact of the applied methods was examined in more detail. Information about the analytical technique, extraction solvent, quantity weighed, calibration method, clean-up, and the experience of the participating laboratories were extracted from the analytical protocols and transcribed into a data matrix which was evaluated by multifactor analysis of variance. The applied measurement technique seems to have a statistically significant influence on the analytical results.     

The Photochemical Behaviour of 5,5-Dimethyl-2(5H)-furanone

The photochemical behaviour of the title compound 2c was investigated in various solvents. In benzene and t-butanol photodimerization affords the cis-anti-cis HH- and HT-dimers (H = head, T = tail). In acetonitrile, cyclohexane and 2-propanol, photoreduction competes with photodimerization. The photoreduction products are hydrodimers, solvent adducts and the saturated lactone (the 2H-reduction product). In acetonitrile and cyclohexane H-abstraction by the β-C-atom of the C?C bond is the predominant reduction process. In 2-propanol, solvent adducts to the α- and β-C-atoms are formed in equal amounts. In xanthone-sensitized irradiations the ratio of HH- to HT-dimer is the same as on direct irradiation and the relative rates of conversion of 2c to products in different solvents are also similar under both conditions.     

Crystal Structures of the Lithium Cryptates of Two Macrobicyclic Ligands Containing Pyridine,Bipyridine, and Biisoquinoline Units

The crystal structures of the LiBr complexes of two macrobicyclic ligands, [py.py.bpy] 1 and [py.biqi.biqi] 2 , have been determined. They confirm the cryptate nature of these species. In 3 , the Li⁺ cation is bound in the shallow cavity of a ligand of flattened shape, whereas in 4 , it is buried inside the macrobicycle and surrounded by its three bridges.     

Analytical challenges: bridging the gap from regulation to enforcement

An overview is presented of the analytical steps that may be needed to determine the presence of genetically modified organisms (GMOs) or for analysis of GMO-derived produce. The analytical aspects necessary for compliance with labeling regulations are discussed along with bottlenecks that may develop when a plant product or a food sample is analyzed for conformity with current European Union GMO legislation. In addition to sampling and testing, other topics deal with complications that arise from biological and agricultural realities that may influence testing capabilities. The issues presented are intended to serve as elements to examine the different challenges that enforcement laboratories might face.     

Differences of Composition Operators between Weighted Banach Spaces of Holomorphic Functions on the Unit Polydisk

We consider differences of composition operators between given weighted Banach spaces H ^∞ _v or H ⁰ _v of analytic functions defined on the unit polydisk D ^N with weighted sup-norms and give estimates for the distance of these differences to the space of compact operators. We also study boundedness and compactness of the operators. This paper is an extension of [6] where the one-dimensional case is treated. Received: May 15, 2007. Revised: October 8, 2007.