A simple and efficient directly suspended droplet micro extraction in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of organochlorine pesticides (OCPs) from water samples. In this technique a micro drop of 1-dodecanol is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Factors relevant to the extraction efficiency were studied and optimized. The optimized extraction conditions were extraction solvent: 1-dodecanol; extraction temperature: 60â—¦C; NaCl concentration: 0.5M; solvent extraction volume: 10 µL; stirring rate: 800rpm and the extraction time: 20 min. The detection limits of the method were in the range of 0.066–1.85 ngL−1, relation standard deviation (n=5) range were 0.102 - 0.964. A good linearity (r 2 ≥0.995) and a relatively broad dynamic linear range (25–2600ng.L−1) were obtained and recoveries of method were in the range of 90.729% - 102.343%. Finally, the proposedmethod was successfully utilized for pre concentration and determination of OCPs in different real samples.We successfully developed a method based on the DSDME technique combined with capillary GC-ECD for the analysis of OCPs in the water samples and compared with the conventional sample preparation method such as LPME.    تفاصيل المقالة

In this work, Magnetic Fe3O4@MCM-41/CuO nanocomposite was preparation of iron oxide magnetite nanoparticles and development of MCM-41 mesoporous shells on the surface of iron oxide magnetite after Fe3O4@MCM-41 was organofunctionalized and finally formation CuO shells with thickness ~ 25-30 nm in the surface of Fe3O4@MCM-41-NH2 core-shell. The properties of prepared magnetic core-shell were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption–desorption measurement and vibration sample magnetometer (VSM). The applicability of the synthesized core-shell was tested as an antimicrobial agent against gram-positive and gram-negative bacteria. It was showed that the Fe3O4@MCM-41@CuO act as an ideal antimicrobial agent in compared with that of the pure copper oxide and Fe3O4@CuO. تفاصيل المقالة