Search

Trichlorfon is an organophosphorus insecticide, which is extensively being used for protection of fruit crops. Trichlorfon is a thermal labile compound, which cannot be easily determined by gas chromatography (GC) and has no suitable group for sensitive detection by high performance liquid chromatography (HPLC). In this study, a 31P nuclear magnetic resonance (31P NMR) has been described for monitoring of trichlorfon without any separation step. The quantitative works of 31P NMR spectroscopy has been performed in the presence of an internal standard (hexamethylphosphoramide). Limit of detection (LOD) for this method has been found to be 55 mg L(-1), without any sample preparation, and the linear working range was 150-5500 mg L(-1). Relative standard deviation (R.S.D.%) of the method for three replicates within and between days was obtained < or =9%. The average recovery efficiency was approximately 99-112%. This method was applied for monitoring trichlorfon in a commercial insecticide sample and tomato sample.

A pseudo four-component reaction is described, leading to the efficient regioselective synthesis of sigma symmetric spiro heterobicyclic rings using aldehydes and urea in the presence of cyclic beta-diester or beta-diamides such as Meldrum's acid or barbituric acid derivatives. The reaction needs no added catalyst and proceeds solvent-free conditions at 80 degrees C.

A novel four-component reaction approach to the efficient synthesis of triamide and amidodiester derivatives using amines or alcohols, aldehydes and alkyl or aryl isocyanides in the presence of Meldrum's acid as a CH acid, instead of carboxylic acid of Ugi four-component reaction, was studied.

A 1H NMR procedure for the monitoring of ampicillin (Amp) and its main related substance in different media, has been developed. The characteristics peak of Amp, 6-aminopenicillanic acid (6-APA), phenylglycine (PhG), and penicilloic acid in the range of 0.5-0.9 and 3.0-4.5 ppm were used for their identification in drugs and serum samples. The quantitative works were performed based on the intensity of protons of the methyl group link to the beta-lactam cyclic of Amp and 6-APA and the aromatic protons of PhG relative to the protons of methylene group of maleic acid, as internal standard, at constant temperature. The resulting data are compared with those obtained with an HPLC method proposed by British Pharmacopoeia. Statistical studies show that, at a confidence limit of %95, there is no significant difference between the two methods. In comparison with the HPLC method, the proposed NMR method does not require any sample pretreatment, standard solution preparation, long analysis time and use of any carcinogenic solvent. The method was applied to the determination of Amp and its related substances in synthetic mixtures, drug powders and serum samples.