Seyyed Hamid Ahmadi

Identification and measurement of pesticides in water is one of the significant public benefits of protecting humans from the effects of water pollution. In this study, a new method was presented for the determination of ethion (ET) as an organophosphate insecticide in water samples based on the use of localized surface plasmon resonance (LSPR) of citrate-capped silver nanoparticles (CC-Ag NPs). The LSPR band was scanned by UV-Visible spectrometer and transmission electron microscopy (TEM) was used to show the interaction, surface features and particle size. By placing CC-Ag NPs in the vicinity of ET, it was observed that the pollutant was adsorbed by silver nanoparticles in aqueous solution. As a result of the adsorption process, aggregation of silver nanoparticles was observed. On the other hand, it was also observed that the ET concentration had a direct effect on the color of the mixture from light yellow to brown. As a result of the aggregation of silver nanoparticles, the adsorption peak in the range of 393 nm was reduced and a new adsorption peak was observed in the wavelength of 540 nm. The absorbance ratio at the wavelength of 540 to 393 nm (A540/A393) was used as the analytical signal. The shift in wavelength and the change in adsorption intensity were the expression of the characteristics of the structure and concentration of the pesticide, respectively. The interaction between the sensor and the pesticide was considered to be the result of the binding of the soft metal surface with the soft sulfur atom of the pesticide. Factors affecting adsorption efficiency were investigated including pH, ionic strength, reaction time and sodium citrate concentration. The proposed method had good repeatability, reproducibility and stability. Finally, the applicability of the proposed method for real sample analysis was examined, which was consistent with the obtained experimental results

In this work, we present a fast, simple and selective method for the extraction/preconcentration and determination of five opium alkaloids. This method is based on the combination of dispersive solid phase extraction with magnetic molecularly imprinted polymers (MMIP) and determination via high performance liquid chromatography. The surface modified Fe₃O₄ nanoparticles were synthesised in-situ, from a co-precipitation method by addition of a mixture of the methacrylic acid and ammonia to a mixture of Fe²⁺/Fe³⁺ under nitrogen atmosphere. MMIP was prepared from surface modified nanoparticles in the presence of ethylene glycol dimethyl acrylate as cross-linker and azobisisobutyronitrile as initiator and template molecule under reflux in acetonitrile. MMIPs for five natural occurring opium alkaloids, including morphine (MO), codeine (CO), thebaine (TE), noscapine (NO) and papaverine (PA) were prepared in the same manner. Structural characterisation and elucidation of both synthesised nanoprticles were performed by Fourier transform-infrared spectroscopy, scanning electron microscopy. X-ray diffraction and vibrating sample magnetometry. A precise chromatographic method was developed and coupled with extraction with MMIP nanoparticles for simultaneous preconcentration and determination of above-mentioned alkaloids in underground water samples. The limit of detection obtained 0.007, 0.007, 0.004, 0.003, 0.003 mg L⁻¹ for MO, CO, TE, NO and PA, respectively and recoveries were about 97–102%. Linear dynamic range and relative standard deviation were 0.03–100 mg L⁻¹ and less than 1.5% for each analyte.

In this research, a poly (ionic liquid) functionalised silica-coated magnetic nanoparticles were synthesised for the first time and utilised as a novel adsorbent for the simultaneous extraction of six phthalic acid esters from polyethylene terephthalate bottled drinking water samples. The adsorbent was prepared by grafting poly (1-benzyl-3-vinyl-1 H-imidazol-3-ium chloride) onto silica-coated Fe₃O₄nanoparticles via Cu(0)-mediated reversible-deactivation radical polymerisation method. Various techniques were used to characterise the synthesised nanomaterials. A qualitative analysis was performed using ultra-performance liquid chromatography triple–quadrupole tandem mass spectrometry. Response surface methodology based on central composite design was used to optimise the extraction procedure and the optimised condition for each factor was; pH of3.9, 22 mg of adsorbent, 3.5 min extraction time, 3 min desorption time, 340 µL of elution solvent (methanol).The results of the validation of the method indicated its acceptable accuracy (88.6-100.1%), good linearity (r > 0.995), satisfactory repeatabilities (RSDs ≤ 6% for intra- and inter–day precisions) and high enrichment factors (535–572). The limits of detection and limits of quantification of the proposed method achieved were 1.1-4.6 ngL^–1and 3.6-15.3 ngL^–1, respectively. In this study, six common PAEs, including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis (2-ethylhexyl) phthalate, and di-n–octyl phthalate, were found in PET bottled water within the range of 0.21-0.94 μgL^–1, under different storage conditions. Nevertheless, only a negligible risk is caused by the PAEs in PET bottled water for consumers following the recommendations, such as storing at a common place (25°C), in a short period away from the sun.