Iranian Journal of Analytical Chemistry
Volume:7 Issue: 2, Summer and Autumn 2020

In the present research, the application of a functionalized ionic liquid with a specific role to simultaneous extraction and preconcentration of cadmium and lead ions in aqueous media by in-situ solvent formation microextraction (ISFME) technique was developed. The task-specific functionalized ionic liquid of 3-(2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)ethyl)-1-methylimidazolium chloride ([Tamim][Cl]) as a complexing agent utilized for the formation of metal chelates with Cd(II) and Pb(II) ions in aqueous solutions. Finally, determination of concentrated or separated metal ions contents after dilution step was carried out by flame atomic absorption spectrometry (FAAS). To obtain optimum extraction conditions, analytical parameters including the various range of sample solution pH, chelating agent amount, ionic strength of solution, solution temperature and counter ion dosage were investigated. Furthermore, parameters represent figures of merit of the method such as limit of detection (LOD), relative standard deviation (RSD), linear dynamic range (LDR) and the enhancement factor (EF) were 0.64;0.76 µg L-1, 1.5;1.8%, 50-2500;50-2000 µg L-1 and 85;80 for cadmium and lead, respectively. The ability of the method for analyzing of real water and saline samples were evaluated and good results were obtained.

The electro-oxidation of acyclovir (ACV) was studied using synthesized Cu nanoparticles stabilized by reduced graphene oxide (Cu/RGO) modified carbon paste electrodes. In this work, leaf extract of rosemary (Rosmarinus officinalis) used as a reducing and stabilizing agent for biosynthesis of copper nanoparticles. The Cu/RGO nanocomposite was authorized by X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) spectroscopy, [1]Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). In an alkaline solution, the electrochemical performance of Cu/RGO was checked and afterward utilized to make a modified carbon paste electrode to study the electrocatalytic oxidation of acyclovir, compared to copper modifier only. Two used methods for surveying of the oxidation reaction were cyclic voltammetry and chronoamperometry. The limit of detection for modified electrode was obtained 0.63 µM. Furthermore, the rate constant of the electrocatalytic oxidation of acyclovir was (1.80 ± 0.03) ×105 cm3mol−1s−1 and the electron-transfer coefficient was (4.00 ± 0.05) ×10–6 Cm2 s–1.

Herein, a simple, rapid, and efficient method based on pH assisted homogenous liquid-liquid microextraction was combined with gas chromatography- mass spectrometry (GC-MS) to do trace analysis of polychlorinated biphenyls (PCBs) in water samples. Triethylamine (TEA) was used as a switchable hydrophilicity solvent which can be miscible/immiscible with aqueous sample by varying the pH of the sample solution. In this regard, the effects of various parameters were explored on the extraction performance of PCBs. Detection limits, quantification limits and linear dynamic ranges were equal to 0.15 µg L-1, 0.5 µg L-1 and 0.5-150 µg L-1 respectively. The RSDs% (n = 3) were in the range of 5.2-6.4 and 5.6-7.2 for intra-day and inter-day assays, respectively. Ultimately, the method was employed for determination of PCBs in water samples.

A ligandless on-line solid phase extraction method was developed for the preconcentration of lead prior to quantitation by inductively coupled plasma-optical emission spectrometry. In this method, the sample solution was passed through a syringe membrane filter coated with graphitic carbon nitride and Pb(II) ions were directly adsorbed on the surface of g-C3N4 particles. The adsorbed Pb(II) ions were subsequently eluted from the membrane and transferred directly into the ICP-OES nebulizer with nitric acid solution. Under the optimized conditions and preconcentration of 25 mL of sample, the enhancement factor of 110 and the detection limit of 0.12 μg L-1 were obtained. The proposed procedure was applied for the preconcentration and determination of lead in environmental water samples.

A chemically modified glassy carbon electrode was developed using multi-walled carbon nanotubes covalently immobilized with 2,6-dichlorophenolindophenol. The immobilization of 2,6-dichlorophenolindophenol with multi-walled carbon nanotubes was characterized by UV–visible absorption spectroscopy and Fourier transform infrared spectroscopy, and was determined using cyclic voltammetry. The cyclic voltammetric response of 2,6-dichlorophenolindophenol grafted onto multi-walled carbon nanotubes indicated that it promoted the electrocatalytic, sensitive and stable determination of sulfide ions. Meanwhile, the dependence of response currents on the concentration of sulfide was also examined and was linear in the range of 1.8 µM – 2.5 mM. The detection limit of sulfide was 1.1 µM, and RSD for 10 and 1000 µM sulfide was 1.8 and 1.3 %, respectively. Many interfering species had little or no effect on the determination of sulfide. This procedure was applied for determination of sulfide in water samples.

Fluorescent chemical sensors to detect drugs, by increasing fluorescence emission and absorption or by shutting down, because they are non-destructive, the ability to show decomposed concentrations, fast response, high accuracy have been considered and used. In this research, a chemical sensor was synthesized PbS functionalized with gelatin quantum dots for (MNZ) drug. The calibration curve was linear in the range of (0.1 to 10.0 µg L−1). The standard deviation of (3.5%), and detection limit of the method (2.2 µg L−1 in time 50 sec, 285 nm) were obtained for sensor level response PbS Quantum Dot–Gelatin Nano composites sensor with (95%) confidence evaluated. The observed outcomes confirmed the suitability recovery and a very low detection limit for measuring the (MNZ) drug. The method fluorometric introduced to measure (MNZ) drug in real samples such as urine and blood was used and can be used for hospital samples. The chemical PbS Quantum Dot–Gelatin Nano composites sensor made it possible as an excellent sensor with good reproducibility.

In this paper, a new rapid and sensitive method based on sodium dodecyl sulfate modified Fe3O4@α–Linolenic acid nanocomposite combined with high-performance liquid chromatography-photo diode array detection (HPLC–PDA) has been proposed for the extraction and determination of tramadol (TRA) in water samples. The Fe3O4@α–Linolenic acid NPs were synthesized and then characterized by Fourier transform-infrared spectroscopy (FT−IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The main factors influencing extraction and desorption efficiency were optimized. Under optimum conditions, the method was successfully applied to the determination of TRA in the environmental samples and good linearity in the range of 0.1–500ng.mL-1(𝑅2> 0.99) obtained. The detection limit (LOD) and relative standard deviation (RSD) were0.074ng.mL-1 and 2.89 %( n=5) respectively. Finally, the proposed method was successfully applied with the relative recoveries percentages from 94–103.97% for the extraction and determination of tramadol in aqueous samples.

The complexation reactions between N-N′-Bis(5-bromo-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine Schiff base ligand and Ag+, Cd2+, Co2+, Cu2+, Hg2+, Ni2+, and Zn2+ ions were studied conductometrically in acetonitrile, dimethylformamide, ethanol, and methanol solvents at 5, 10, 15, and 25ºC. The formation constants of the resulting ML and M2L complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. The selectivity of the Schiff base ligand to the cations is depended the nature of the solvent. At 25ºC in acetonitrile solvent, the stability of the resulting complexes varied in the order Hg2+ > Ag+ > Cd2+ > Cu2+ > Co2+ > Zn2+ > Ni2+. It was found that the stability of the resulting complexes decreased with increasing the solvation ability of the solvent. The values of the thermodynamic parameters (ΔH°, ΔS° and ΔG°) for complexation reactions were obtained from the temperature dependence of the stability constants values (log Kf) using the Van’t Hoff plots. In most cases, the complexes were found to be an enthalpy and entropy stabilized.

Bromopyrogallol Red (BPR) dye (Dibromopyrogallolsulfonphthalein), was evaluated as a highly selective colorimetric chemosensor for tin and citrate ion. BPR displayed rapid response, high specificity, visual determination and good selectivity toward tin and citrate ion over other competing cations and anions in DMSO/H2O (1:1 v/v) media. The sensing mechanism was discussed by UV–Vis, titration, and a comparison study. Over a wide range from 0.4 µmol L-1 to 153.8 µmol L-1 and 0.02 µmol L-1 to 1.08 µmol L-1, a good linear relationship between the absorbance and the concentration of tin and citrate ion was found respectively and the detection limit was estimated to be as low as 0.06 and 0.003 µmol L-1 (S/N = 3) for tin and citrate ion. This proposed chemosensor has also been successfully applied for the determination of citrate in real samples which demonstrates its value of practical applications in food and biological systems.

Herein, the electrooxidation of ascorbic acid and folic acid, as two essential vitamins, on the surface of the carbon ceramic electrode modified by polydopamine and copper (Cu/PDA/CCE) was investigated. Poly dopamine was fabricated by applying electro deposition conditions. Initial electrochemical characteristics were performed to study the behavior of the fabricated electrode for simultaneous detection of two biomolecules. From voltametric studies using the developed electrode, two separated anodic peaks for folic acid and ascorbic acid were found promisingly for concurrent detection of the compounds. Linear calibration diagrams were obtained in the range of 0.5 to 360 μM and 0.83 to 380 μM with detection limits of about 0.031 and 0.057 μM for folic acid and ascorbic acid, respectively. The developed electrode was applied in human urine sample analysis with satisfying results.

This work presents a fast, feasible, and sensitive method for the preconcentration and separation of cobalt in various real samples through the use of deep eutectic solvent-based dispersive liquid-liquid microextraction (DESDLLME) in which deep eutectic solvent, methanol, and 1-(2-pyridylazo)-2-naphthole (PAN) were employed as extraction solvent, dispersive solvent, and complexing agent, respectively. Co concentration was measured by flame atomic absorption spectrometer. Effective parameters which may influence the extraction efficiencies (like type and volume of the dispersive and extraction solvent, pH, PAN concentration, and salt concentration) were examined and the optimal values were determined. The use of optimal conditions resulted in a limit of detection equal to 1.5 μg/L with a preconcentration factor of 40. RSD value, after measuring 20.0 μg/L of cobalt for 10 times, resulted in a value of 3.0 %. The methodʼ s accuracy and applicability were assessed through the evaluation of Co content in water certified reference materials and different agricultural and water specimen.

Silver nanoparticles (Ag NPs)-reduced graphene oxide was prepared through the in situ nucleation of Ag NPs on reduced, modified GO (rMGO). Glycine was used as a green reducing as well as modifier agent for GO to obtain rMGO. Nucleation of Ag NPs on rMGO was carried out at 80 ◦C at aqueous media. UV-Vis, FT-IR, and XRD techniques confirmed the reduction, modification, and synthesis of Ag NPs. Meanwhile, the morphology of rMGO and rMGO-Ag nanocomposite was investigated with SEM and TEM images. The synthesized nanocomposite showed excellent catalytic behavior for the reduction of 4-nitrophenol (4-NP) by NaBH4. The electrocatalytic behavior of Ag NPs on rMGO for electroreduction of H2O2 was investigated by cyclic voltammetry (CV). In the optimum condition, H2O2 was determined with a detection limit of 9.4 µM and sensitivity of 0.52 µAµM-1. In addition, with the investigation of MIC data of nanocomposite, it was distinguished that this compound has excellent antibacterial activity.