Iranian Journal of Analytical Chemistry
Volume:4 Issue: 2, Summer and Autumn 2017

A simple and a green methodology has been developed for the preconcentration of Ni2+ based on the adsorption of its dimethylglyoximate complex on polydopamine coated Fe3O4 nanoparticles. The adsorbed complex was easily desorbed using 1.0 mL of CHCl3 and the concentration of nickel was determined by UV-Vis spectrophotometry. The effects of pH, sorbent mass, extraction time on the sorption of nickel dimethylglyoximate complex were investigated using Box–Behnken design. In optimal experimental conditions, a wide linear range of 5.0-600.0 μg/L with detection limit of  1.49 μg/L was obtained. The proposed method was applied for extraction and preconcentration of Ni2+ in various food samples and the results were compared with the official AOAC method.

In this work, a microextraction technique based on pipette tip solid-phase extraction was used for preconcentration and determination of diazinon. Carbon nanotube functionalized by zinc sulfide and ethylene glycol was used as sorbent. Determination of diazinon was performed using high performance liquid chromatography and UV detection. Important parameters that influence the extraction efficiency (i.e. pH, amount of adsorbent, extraction time, salt addition, volumes of sample and eluting solvent and number of aspirating/dispensing cycles for both solvent and sample) were investigated and optimized. Results were showed that method was validated over the range of 0.50 - 100.0 µg L-1. Repeatability was satisfactory, bellow 3.78% for 5 replicate measurements of 20 µg L-1 of diazinon. The limit of detection of this method is 0.03 µg L-1 with an enrichment factor of 100 and short extraction time of 8.5 min, which confirmed suggested method is a reliable and accurate for extraction and preconcentration of diazinon.

The catalytic degradation of 4-chloro 2-nitro phenol aromatic compound has been studied with coupled ozone-sonolysis method. The response surface methodology was used to optimize the influence of operation parameters on the catalytic degradation of 4-chloro 2-nitro phenol. In order to evaluate the influence of operation conditions in the degradation of 4-Chloro 2-Nitro Phenol, four independent variable chosen: 4-Chloro 2-Nitro Phenol concentration, mass flow rate of O3, TiO2 concentration and ultra sonic power. Analysis of variance was employed to consider main factors effects and interactive effects in the optimization of catalytic degradation of of 4-Chloro 2-Nitro Phenol. Analysis of variance results present that the model is statistically significant. The response surface methodology predictions were in agreement with the experimental values.

Fe3O4 magnetic nanoparticles modified with alizarin red S (ARS-Fe3O4) were used for the removal of several metal ions from aqueous solution. The mean size and the surface morphology of the nanoparticles were characterized by TEM, XRD and FTIR techniques. Adsorption studies of mentioned metal ions were performed in batch system. The adsorption of metal ions onto ARS-Fe3O4nanoparticles was affected by the several analytical parameters such as an initial pH, metal ions concentration, adsorbent amount, contact time and temperature. Experimental results indicated that ARS-Fe3O4 nanoparticles were quantitatively removed. The maximum adsorption capacities ofARS-Fe3O4 for the Langmuir model were 50.0, 22.7 and 21.7 mg of metal ions per gram of nanoparticle for Zn2+,Cu2+and Pb2+, respectively. The isotherm evaluations revealed that the Langmuir model attained better fits to the equilibrium data than the othermodels. The kinetic data of adsorption of Zn2+,Cu2+and Pb2+ ions on the synthesized adsorbents were best described by pseudo-second-order equation. The adsorption processesfor three metal ions were endothermic. Metal ions were desorbed from nanoparticles by 2 mLHCl solution 0.1 mol L−1.

A rapid, selective and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) assay has been proposed for the determination of Clavulanic acid (CA) in human plasma using Diclofenac sodium as internal standard (IS). The analyte and IS were extracted from human plasma via solid phase extraction and the chromatographic separation was achieved on Inertsil ODS-3, 50 x 4.6 mm, 5µ column under isocratic conditions. Detection of CA and IS was done by tandem mass spectrometry, operating in positive ionization and multiple reaction monitoring (MRM) acquisition mode. The protonated precursor to product ion transitions monitored for CA and IS were m/z 365.2→240.2 and 409.2→228.2, respectively. The method was fully validated as per the US FDA guidelines. The linear dynamic range of CA was 7.564 - 897.893 ng/mL. The intra-batch and inter-batch precision (%CV) was ≤ 14.1% while the mean extraction recovery was 84.48 % across quality control levels. It was successfully applied to a bioequivalence study of Cefdinir/CA (125 mg/62.5 mg) suspension formulation in 32 healthy Indian male subjects under fasting condition.

A novel switchable-hydrophilicity solvent based liquid phase microextraction (SHS-LPME) coupled with flame atomic absorption spectrometry has been applied for preconcentration and extraction of Ag(I). In this study, Triethylamine (TEA) was selected as switchable solvent. The Ag (I)-1-(2-pyridylazo)-2-naphthol complex was extracted into organic phase by converting the protonated carbonate (P-TEA-C) to TEA. The experimental conditions were optimized using Plackett–Burman and Box–Behnken design methods. Under the optimum conditions, the detection limit, relative standard deviation and the enrichment factor were 0.35 μg L-1, 1.4% and 68, respectively. The calibration graph was linear over the range 2 to 500 μg L-1 with correlation coefficient of 0.997. The proposed method was successfully applied to determine of trace silver in water samples.

In this research poly (Styrene–Alternative-Maleic Anhydride) (SMA) and derivations of SMA with Melamine, (Melamine + 1,2 Diamino Ethane) and (Melamine + 1,3 Diamino Propane)  CSMA-M, CSMA-ME and CSMA-MP  were synthesized, respectively. This method is very simple, cheap, precise and used polymers recyclable to seven terms. The purpose of the present work was exploring the adsorption power of CSMA-M and its derived polymer  to removed silver(I) ions from aqueous solution. In this research, batch adsorption tests were exhibited and the effect of different parameters on this removal process has been studied. The effects of pH, adsorption time, metal ion concentration and the acidic remedy on the adsorption process were optimized. The optimum pH for adsorption was found to be 6.0. In adsorption explores, remained Ag+ concentration arrives equilibrium in a short duration of 60 min. Maximum adsorption capacity, 67.57, 76.90 and 95.24 mg Ag+/g polymer CSMA-M, SMA–ME and SMA–MP respectively.showed that this adsorbents were appropriate for removing silver(I) from aqueous solution. The resins were characterized by Fourier transform Infra Red(FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), X-ray diffraction(XRD) and Differential Scanning Calorimetry (DSC), (Thermo Gravimetric Analysis) TGA analysis.