Analysis of trace elements (Cu, Cd, and Zn) in the muscle, gill, and liver tissues of some fish species using anodic stripping voltammetry

Heavy metal (Cu, Cd, Zn) concentration of the muscle, gill, and liver of Otolithes rubber, Pampus argenteus, Parastromateus niger, Scomberomorus commerson, and Onchorynchus mykiss are determined by anodic stripping voltammetry method. The results show that the concentration of Cu, Cd, and Zn varied between 0.44 and not detected, 0.585 and 0.001, and 0.450 and 0.005 μg/g, respectively. It is interesting that in O. mykiss, the mean value of copper concentration was more than other marine organisms of this study, while in P. niger, the mean value of copper was minimum. The results of this study indicate that in the different tissues of fish species (O. rubber, P. argenteus, P. niger, S. commerson, and O. mykiss), the concentrations of Cu, Cd, and Zn were significantly lower than the permissible FAO/WHO levels.

Phytoextraction and phytostabilization potential of plants grown in the vicinity of heavy metal-contaminated soils: a case study at an industrial town site

With the development of urbanization and industrialization, soils have become increasingly polluted by heavy metals. Phytoremediation, an emerging cost-effective, nonintrusive, and aesthetically pleasing technology that uses the remarkable ability of plants to concentrate elements, can be potentially used to remediate metal-contaminated sites. In this research, two processes of phytoremediation (phytoextraction and phytostabilization) were surveyed in some plant species around an industrial town in the Hamedan Province in the central-western part of Iran. To this purpose, shoots and roots of the seven plant species and the associated soil samples were collected and analyzed by measuring Pb, Fe, Mn, Cu, and Zn concentrations using ICP-AES and then calculating the biological absorption coefficient, bioconcentration factor, and translocation factor parameters for each element. The obtained results showed that among the collected plants, Salsola soda is the most effective species for phytoextraction and phytostabilization and Cirsium arvense has the potential for phytostabilization of the measured heavy metals.

A new catalytic-spectrophotometric method for quantification of trace amounts of nitrite in fruit juice samples

A new kinetic method has been developed for the determination of nitrite in fruit juice samples. The method is based on the catalytic effect of nitrite with the oxidation of Nile Blue A (NBA) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 1.2 mM sulfuric acid, 0.034 mM of NBA, 2.8 × 10(-3) M KBrO(3), reaction temperature of 20 °C, and reaction time of 100 s at 595.5 nm. Under the optimized conditions, the method allowed the quantification of nitrite in a range of 0.2-800 μg/mL with a detection limit of 0.02 μg/mL. The method was applied to the determination of nitrite in 15 brands of fruit juice samples.

Quantification of sub-nanomolar levels of Penicillin G by differential pulse adsorptive stripping voltammetry

A novel selective and sensitive method is developed for determination of Penicillin G by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV). Penicillin G gave well-resolved diffusion-controlled cathodic peaks at -0.42 and -0.584 V, respectively (vs Ag/AgCl) in pH 7.50 of borate buffer. Optimal conditions were obtained as pH 7.50, accumulation potential of -0.2 V (vs Ag/AgCl), accumulation time of 120 s, and scan rate of 100 mV/s. Under the optimized conditions, a linear calibration curve was established for the concentration of Penicillin G in the range of 0.007-2.13 µg/ml with a detection limit of 0.000717 µg/ml. The procedure was successfully applied to the determination of Penicillin G in various medicine and biological samples. The relative standard deviation of the method at 0.05 and 0.5 µg/ml Penicillin G, for 10 runs, was 2.55% and 2.06%, respectively.

Sensitive nanosilver-based spectrophotometric determination of Brilliant Blue FCF in surface water samples

An accurate method was developed for the determination of Brilliant Blue FCF, a synthetic soluble colorant, in environmental samples. The method is based on the catalytic effect of silver nanoparticles (AgNPs) on the oxidation of Brilliant Blue FCF by hexacyanoferrate(III) in acetate-acetic acid medium at room temperature. Linearity of around four orders in the magnitude of concentration was generally obtained. Detection and quantification limits of the investigated dye, which was evaluated at a signal-to-noise ratio of 3 for detection limit and quantification limit, were 0.1 and 0.6-130.0 ng/mL, respectively. The recoveries of the synthetic colorant Brilliant Blue FCF in environmental matrices (surface water) ranged from 95.0 to 101.0%. Relative standard deviation of less than 3.1% was also achieved. This method has been applied successfully in the determination of water-soluble colorant Brilliant Blue FCF in surface water samples.

New kinetic-spectrophotometric method for monitoring the concentration of iodine in river and city water samples

A new kinetic method has been developed for the determination of iodine in water samples. The method is based on the catalytic effect of I(-) with the oxidation of Indigo Carmine (IC) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 0.16 M sulfuric acid, 1 × 10(-3) M of IC, 1 × 10(-2) M KBrO(3), reaction temperature of 35°C, and reaction time of 80 s at 612 nm. Under the optimized conditions, the method allowed the quantification of I(-) in a range of 12-375 ng/mL with a detection limit of 0.46 ng/mL. The method was applied to the determination of iodine in river and city water samples with the satisfactorily results.

pK(a) modelling and prediction of drug molecules through GA-KPLS and L-M ANN

Genetic algorithm and partial least square (GA-PLS), kernel PLS (GA-KPLS) and Levenberg- Marquardt artificial neural network (L-M ANN) techniques were used to investigate the correlation between dissociation constant (pK(a) ) and descriptors for 60 drug compounds. The applied internal (leave-group-out cross validation (LGO-CV)) and external (test set) validation methods were used for the predictive power of models. Descriptors of GA-KPLS model were selected as inputs in L-M ANN model. The results indicate that L-M ANN can be used as an alternative modeling tool for quantitative structure-property relationship (QSPR) studies.

A new nanosilver-based spectrophotometric method for monitoring Eriochrome black T in river water

In this paper, a new spectrophotometric method is reported for the determination of nanomolar levels of Eriochrome black T in environmental samples. The method is based on the catalytic effect of silver nanoparticles on the oxidation of Eriochrome black T by hexacyanoferrate (III) in acetate-acetic acid medium and at 25 °C. The absorbance is measured at 512 nm with the fixed-time method. It relies on the linear relationship between the absorbance difference (∆A) and Eriochrome black T amounts in the range of 40-1,250 nM. Under optimum conditions, the sensitivity of the proposed method, i.e., the detection limit corresponding to 80 s, is about 25 nM. The method is featured with good accuracy and reproducibility for Eriochrome black T determination in river water samples without any pre-concentration and separation step.