Amir Hossein Mohsen Sarrafi

In this work, toner powder as a magnetic adsorbent coupled with a dispersive solid phase extraction (DSPE) method was proposed for the pre‐concentration and separation of Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ in vegetable samples and aqueous environments. Flame atomic absorption spectrometry (FAAS) was used for the final analysis of the ions. Adsorbent characterization was studied by scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction analysis (XRD), and vibrating‐sample magnetometer (VSM). The effect of experimental factors on the extraction efficiency was investigated by Box‐Behnken design (BBD). The maximum recovery percentage was found to be 95.40%, 95.40%, and 97.40% for Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ , respectively. In the optimum conditions, the linearity ranges were obtained 12–200, 1–150, 0.4–100 μg L ⁻¹ for the Pb, Cd, and Zn ions, respectively. The limit of detection (LOD) of the method was found 3.60, 0.30, and 0.11 μg L ⁻¹ for the Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ , respectively. The suggested procedure indicated to be appropriate, cost‐effective, and eco‐friendly for extraction of mentioned metal ions in different vegetables and water samples with high precision and accuracy.

A TiO₂@WO₃/ZnO photocatalyst was synthesized and employed in the degradation of methyldiethanolamine (MDEA) (a pollutant of wastewater from gas refinery complexes) under LED light. The synthesized photocatalyst was characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectrometry (FT-IR). In the wastewater treatment process, a number of experiments were designed by central composite design, where parameters including the irradiation time, pH, TiO₂@WO₃/ZnO catalyst mass and MDEA concentration involved in the process were optimized. The significance of the individual parameters and their possible interactions were investigated using analysis of variance. The optimum values of 30 min, 9, 0.15 g, and 0.4% were obtained for the irradiation time, pH, TiO₂@WO₃/ZnO catalyst mass ratio and the initial concentration of MDEA, respectively. Under such conditions, the photodegradation percentage of MDEA was 86%, and a maximum photocatalytic activity with 72% degradation of gas refinery effluent was achieved in 70 min.

In this study, dispersive liquid‐liquid microextraction method based on solidification of floating organic drop (DLLME‐SFO) was developed for the preconcentration of trace amount of Pb(II) and Cd(II) in vegetable and fruit extracts (DIW, Apple, Kiwi, Banana, Orange, Mint, Dill, Savory, and Thyme) and determination of these ions by flame atomic absorption spectroscopy (FAAS). The proposed method is based on the formation of an ion association Pb‐ 4‐(2‐thiazolylazo) resorcinol (TAR) ‐ zephiramine chloride (ZCl) and Cd‐4‐(2‐thiazolylazo) resorcinol (TAR) ‐ zephiramine chloride (ZCl) and then extraction of the resulting complex in micro‐droplets of the extraction solvent. Response surface methodology (RSM) based on the Box‐Behnken Design (BBD) was applied to optimize the experimental variables and evaluate the effect of factors. Optimal conditions were obtained with pH=6, 0.6 mL of the ligand solution 4‐(2‐thiazolylazo) resorcinol 0.2 %, 221 μL of 0.2 % zephiramine chloride, 130 μL of 1‐undecanol as solvent extraction, and 530 μL of acetonitrile. The linear range was 3.8‐200 and 1.0–160.0 μg L ⁻¹ with a coefficient of determination (R ² ) of 0.9976 and 0.9985 for Pb (II) and Cd(II), respectively. The limit of detection (LOD) was found to be 1.2 and 0.3 μg L ⁻¹ for Pb (II) and Cd(II), respectively. According to the results of market samples, the recovery (%) of the interday and intraday related to the Pb(II) were in the range of 94.67 % to 103.33 % and 95.33 % to 104.00 % for fruits and vegetables, respectively. Also, the relative standard deviation (RSD%) values of Pb(II) corresponding to the interday and intraday were found to be 1.52 % to 4.36 % and 2.15 % to 4.54 % for fruits and vegetables, respectively. In addition, the recoveries of Cd(II) were obtained 96.33 % to 104.00 % and 97.33 % to 103.33 % for fruits and vegetables, respectively. The RSD values of Cd(II) were 2.09 % to 4.19 % and 2.15 % to 4.54 % for fruits and vegetables, respectively. DLLME‐SFO uses an extraction solvent with lower toxicity instead of highly toxic solvents in other methods and high extraction recovery within a short period of time is possible.

Chemometric and statistic approaches were applied to optimize and validate headspace-single drop microextraction-based deep eutectic solvents combined with gas chromatography-mass spectrometry. The proposed technique was used for the pre-concentration, separation, and detection of polyaromatic hydrocarbons in aqueous samples. The efficacy of the independent variables on the extraction efficiency was studied via chemometric methods in two steps. The method exhibits good linearity for the analytes (R² ≥ 0.9989). Under optimal conditions, the analytical signal was linear in the range of 0.01–50 μg L⁻¹. The limit of detection and limit of quantitation were evaluated in the concentration range of 0.003–0.012 and 0.009–0.049 μg L⁻¹, respectively. The precision consisting of repeatability and reproducibility were assessed by estimating the relative standard deviation (RSD%), and their values were found to be lower than 7.1% and 11.7%, respectively. Consequently, the proposed procedure was used to extract and analyze 19 polyaromatic hydrocarbons in real aqueous samples, which demonstrated satisfactory recoveries (94.40–105.98%).

A quick, simple and efficient method for extraction, preconcentration, and determination of naproxen in water and plasma specimens with acceptable recovery by dispersive liquid-liquid microextraction based on solidified floating organic drop with spectrofluorimetry is presented. Various parameters affecting the extraction efficiency are optimized by the Central Composite Design. Moreover, under optimal conditions (120 μL 1-Undecanol with 1 mL Ethanol, pH = 3.5, 2 mL KCl 10% solution), the calibration curve was linear in the range 10.0–120.0 ng/mL. Finally, for naproxen, the detection limit was 2.4 ng/mL.

The present study sought to develop a facile and green synthetic approach for producing fluorescent carbon dots (CDs) from a natural biomass using aqueous extraction of carbonized blue crab shell. Spherical carbon dots (6.00 ± 3.0 nm) exhibited an extended emission range with excellent quantum yield (14.5 ± 3.5%). In order to measure ceftriaxone, we offered a simple and sensitive method, based on fluorescence quenching of carbon dots in plasma and water with recovery values of 94.5–104.1%. Furthermore, with usage of central composite design (CCD) based response surface methodology (RSM); we optimized the effect of different factors. In addition, ANOVA evaluated the accuracy and suitability of quadratic model. Under optimal conditions, fluorescence quenching revealed a sensitive response in the concentration range of 20–1000 nM with the limit of detection 9.0 nM for ceftriaxone. Finally, carbon dots-based fluorescence quenching procedure was able to quantify ceftriaxone in plasma, as well as mineral and tap water. Spiked samples achieved satisfactory efficiencies.

In this study, a novel solid phase microextraction fiber coating based on a polyamide–graphene oxide nanocomposite was prepared using an electrospinning technique on stainless steel wire as a robust substrate. Scanning electron microscopy images showed the high porosity of the synthesized polyamide–graphene oxide nanocomposite and the diameter of nanofibers to be in the range of 100–250 nm. The method feasibility was studied by the extraction of polycyclic aromatic hydrocarbons as model compounds from water samples. The important factors of the electrospinning procedure and extraction processes such as the polymer concentration, amount of graphene oxide nanoparticles, power voltage, electrospinning time, extraction temperature and time, ionic strength and desorption conditions were studied and optimized. The developed method is fast and sensitive, providing sub and low ppt detection limits, a limit of detection of 0.7–1 ng L⁻¹ and a limit of quantification of 2–5 ng L⁻¹ at an equilibrium time of 15 minutes. A wide linearity in the range of 5–2000 ng L⁻¹ with R > 0.9995 was also obtained. The repeatability of the method was assessed at 100 ng L⁻¹ and a relative standard deviation of 5–10% was achieved. Finally, the developed method was applied to real water samples and the relative recoveries were found to be in the range of 89–101%, showing no matrix effect.