Hochdruckflüssig-chromatographische Bestimmung von Biotin in Arzneimitteln

Analytical and Bioanalytical Chemistry - Die Derivatisierung von Biotin mit 9-Anthryldiazomethan wird beschrieben. Die Umsetzung verläuft reproduzierbar auch im unteren Nanomol-Bereich. Das...     

2,6-Diarylhexahydro-4-pyridazinols by acid-catalyzed cyclization of benzaldehyde aryl-2-(2-propenyl)hydrazones

Treatment of benzaldehyde l-(2-propenyl)-4-methylsulfonylphenylhydrazone ( 1f ) with 45% sulfuric acid gave 2-(4-methylsulfonylphenyl)-6-phenylhexahydro-4-pyridazinol ( 2f ) in 35% yield rather than the expected 1-(4-methylsulfonylphenyl)-1-(2-propenyl)hydrazine. The halogen-substituted hydrazones 1c-1e and benzaldehyde 1-(2-methyl-2-propenyl)phenylhydrazone ( 1b ) gave similar results.     

Magnetische Eigenschaften von Hf2Fe und Hf2FeH x

The weakly temperature dependent paramagnetic compound Hf₂Fe becomes ferromagnetic by hydrogen absorption, theCurie-temperature of the resulting hydrides depends on the hydrogen content.

     

Computer systems for analytical chemistry

Microcomputers are becoming integral parts of all analytical instrumentation and 'personal computers' are invading the laboratory. The analytical chemist is confronted with the question of how to computerize his work and what to request from a computer system. This article attempts to provide some guidelines.     

Isomer-Selective Generation and Spectroscopic Characterization of Picolyl Radicals

Nitrogen-containing resonance-stabilized radicals such as the picolyl radical are important in combustion chemistry and astrochemistry. They have only been scarcely studied because an isomer-selective generation is often difficult. Herein, we present threshold photoelectron spectra of the three picolyl radical isomers, C₆H₆N, that were obtained with synchrotron radiation. The radicals were selectively generated by flash pyrolysis from aminomethylpyridine precursors through deamination. Ionization energies of 7.70, 7.59, and 8.01 eV were determined for 2-, 3-, and 4-picolyl, respectively. The observed vibrational structure was assigned to an in-plane deformation mode of the aromatic ring. The spectroscopic insight gained in this study can be used to distinguish different picolyl isomers in on-line combustion analysis, for example.     

A practical approach to screen for authorised and unauthorised genetically modified plants

In routine analysis, screening methods based on real-time PCR are most commonly used for the detection of genetically modified (GM) plant material in food and feed. In this paper, it is shown that the combination of five DNA target sequences can be used as a universal screening approach for at least 81 GM plant events authorised or unauthorised for placing on the market and described in publicly available databases. Except for maize event LY038, soybean events DP-305423 and BPS-CV127-9 and cotton event 281-24-236 × 3006-210-23, at least one of the five genetic elements has been inserted in these GM plants and is targeted by this screening approach. For the detection of these sequences, fully validated real-time PCR methods have been selected. A screening table is presented that describes the presence or absence of the target sequences for most of the listed GM plants. These data have been verified either theoretically according to available databases or experimentally using available reference materials. The screening table will be updated regularly by a network of German enforcement laboratories.     

Direct Electrochemical Capture and Release of Carbon Dioxide Using an Industrial Organic Pigment: Quinacridone

Limiting anthropogenic carbon dioxide emissions constitutes a major issue faced by scientists today. Herein we report an efficient way of controlled capture and release of carbon dioxide using nature inspired, cheap, abundant and non‐toxic, industrial pigment namely, quinacridone. An electrochemically reduced electrode consisting of a quinacridone thin film (ca. 100 nm thick)on an ITO support forms a quinacridone carbonate salt. The captured CO₂ can be released by electrochemical oxidation. The amount of captured CO₂ was quantified by FT‐IR. The uptake value for electrochemical release process was 4.61 mmol g^?1. This value is among the highest reported uptake efficiencies for electrochemical CO₂ capture. For comparison, the state‐of‐the‐art aqueous amine industrial capture process has an uptake efficiency of ca. 8 mmol g^?1.