This work describes a novel Fe 3 O 4 @SiO 2 @polypyrrole magnetic nanocomposite and its application in the preconcentration of Cd(II) and Ni(II) ions. The parameters affecting the preconcentration procedure were optimised by a Box-Behnken design using response surface methodology. Three variables (extraction time, magnetic sorbent amount, and pH) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent, and elution time) were selected as the main factors in the optimisation study of the elution step. Following the sorption and elution of analytes, the ions were quantified by FAAS. The limits of detection were 0.3 and 1.2 ng mL À1 for Cd (II) and Ni(II) ions, respectively. All the relative standard deviations were less than 8.8%. The obtained sorption capacities (in mg g À1 ) of this new sorbent were 120 for Cd(II) and 98 for Ni(II). Ultimately, this nanocomposite was successfully applied to the rapid extraction of trace quantities of heavy metal ions from seafood samples, and satisfactory results were obtained.

This work describes a novel Fe3O4@SiO2@polythiophene magnetic nanocomposite and its application in the preconcentration of Hg(II) ions. The parameters affecting the preconcentration procedure were opted by a Box-Behnken design through response surface methodology. Three factors (uptake time, magnetic nanosorbent amount, and pH of sample) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent as well as the elution time) were selected as main factors in the optimization study of the elution step. Following the sorption and elution of Hg(II), it was quantified by cold vapor atomic absorption spectrometry. Under the optimum condition, the limit of detection was 0.02 ng mL(-1) and all the relative standard deviations were less than 9.2 %. The obtained sorption capacity of this new sorbent was 59 mg g(-1). Finally, this nanocomposite was successfully applied to the rapid extraction of trace quantities of Hg(II) ions in sea food samples and satisfactory results were obtained.

This work describes the synthesis and application of a novel magnetic metal–organic framework (MOF) [(Fe3O4-dipyridylamine)/MIL-101(Fe)] to preconcentrate trace amounts of Cd(II), Pb(II), Co(II), and Ni(II) ions and their determination by flame atomic absorption spectrometry. A Box–Behnken design was used to find the parameters affecting the preconcentration procedure through response surface methodology. Three factors including sorption time, amount of the magnetic sorbent, and pH of sample were selected as affecting factors in the sorption step, and four factors including type, volume and concentration of the eluent as well as the elution time were selected in the elution step for the optimization study. These values were obtained as 30 mg, 11 min, 6.5, EDTA + HNO3, 4.3 mL, 0.7 mol L−l EDTA in 0.13 mol L−l HNO3 solution, 14 min, for amount of the magnetic sorbent, sorption time, pH of sample, type, volume, and concentration of the eluent, and elution time, respectively. The limits of detection (LODs) were 0.13, 0.75, 0.3, and 0.5 ng mL−1 for Cd(II), Pb(II), Co(II), and Ni(II) ions, respectively. The relative standard deviations (RSDs) of the method were less than 9.2% for five separate batch experiments for the determination of 30 µg L−1 of Cd(II), Pb(II), Co(II), and Ni(II) ions. The sorption capacity of [(Fe3O4-dipyridylamine)/MIL-101(Fe)] was 188 mg g−1 for cadmium, 201 mg g−1 for lead, 173 mg g−1 for cobalt and 154 mg g−1 for nickel. Finally, the magnetic MOF nanocomposite was successfully applied to rapid extraction of trace amounts of heavy metal ions in fish samples.

The reaction of diaminoglyoxime with aldehyde and ketone derivatives in the presence of p-toluene sulphonic acid in H 2 O-MeOH mixture at room temperature afforded nitrone derivatives in high yields within 10-140 min. The applicability of ketones in this reaction for the preparation of novel nitrones has been verified. The effect of the temperature on the stability of the structural isomers of the products has been studied by NMR as well. The results showed that, at high temperatures only one product could be observed. The nature of solvent and catalyst were evaluated and found that the strong acids H 2 SO 4 and CF 3 SO 3 H in protic solvent CH 3 OH work well while neither CH 3 SO 3 H in protic solvent nor p-toluene sulphonic acid in aprotic solvents toluene and THF perform the same reactions.