A Practical and Efficient Synthesis of 2,5-Disubstituted-3,5-dihydro-imidazol-4-ones from Oxazolones

An alternative procedure for the synthesis of 2,5-disubstituted-3,5-dihydro-imidazol-4-ones from substituted oxazolones was evaluated. The initial oxazolone ring-opening reaction was examined with a variety of ammonia source compounds followed by the subsequent 3,5-dihydro-imidazol-4-one cyclization reaction, which was carried out with either an organic or inorganic base in aprotic solvents. In this article, we report the results of an efficient and straightforward procedure for the synthesis of 2,5-disubstituted-3,5-dihydro-imidazol-4-ones that gives satisfactory yield and quality.     

Eine neue Methode der Zuckertitrirung mit ammoniakalischer Kupferl?sung

Ohne Zusammenfassung     

Determination of sulfamethazine in milk by biosensor immunoassay

A biosensor based on surface plasmon resonance (SPR) measurement was developed for use in an immunoassay for detection of sulfamethazine (SMZ) in milk. The biospecific surface was a carboxymethyl dextran-modified gold-surface sensor chip to which SMZ was covalently bound. The assay was based on inhibition of the binding of polyclonal antibodies to immobilized SMZ by SMZ in the sample. The SPR response changed inversely in relation to the antibiotic concentration in the sample. Calibration curves were constructed for SMZ in buffer and in milk at a concentration which included the maximum residue limit (0 to 200 micrograms/kg). The analysis time per sample varied from 8 to 30 min. Different flow rates and antibodies were modified alternatively during the study to assess their influence on the performance of the assay. The active antibody concentration was calculated at approximately 1880 and 180 nM for the antibody anti-SMZ 1 and the antibody anti-SMZ 2, respectively. No cross-reactivity of antibodies with other antibiotics was found. Under optimal conditions, the detection limits in milk for SMZ were 8 and 1.7 micrograms/kg, respectively, for antibody 1 and antibody 2, at a flow rate of 20 microL/min.