فهرست مطالب zohreh doroudi

In this research, an ultrasound-assisted surfactant emulsification microextraction technique was established as a facile, practicable and eco-friendly method for preconcentration of carmoisine (CMS) before its spectrophotometric measurement. Zephiramine and CCl4 were selected as the emulsifier and organic extractant solvent respectively. Box–Behnken design was employed for the optimization of various influencing factors in the extraction process. Under the optimized conditions, the preconcentration and enrichment factors were 666 and 630 respectively.. The limit of detection (LOD) of the designed analytical that was calculated as three times the signal-to-noise ratio (S/N) was 0.15 ng. mL-1. The limit of quantification (LOQ) was 0.47 ng. mL-1 and the working dynamic range was 0.5-80 ng. mL-1 with the correlation coefficient of 0.9995. At the end, the applicability of the designed extraction technique for the quantitation of CMS in four real specimes was also inspected and all of the calculated recovery values were between 97.5-104.2% showed the designed technique can be employed for CMS measurement in real specimens.  .

In this research, a coated graphite electrode based on quetiapine as a neutral ion carrier was constructed for determination of Mg2+. The designed sensor demonstrates an ideal Nernstian slope (30.2 mV. Decade-1) over a wide concentration range (1×10-7- 1×10-2 M). The detection limit of the proposed sensor was 8×10-8 Mol L-1. The selectivity of the sensor was evaluated over 24 different cations by matched potential method and no serious interference was observed from them. The designed electrode could also be used in partially non aqueous mediums up to the presence of 20% of organic solvents without any tangible change in Nernstian slope and linearity domain. The response time and life span of the proposed electrode were 5s and 3 months respectively. The potential response of the sensor was independent from pH in the pH range of 3.0-8.0. At the end, the applicability of the designed sensor as an indicator electrode in potentiometric titration of Mg2+ with EDTA and determination of magnesium in some pharmaceutical products as real samples was also evaluated.

Cadmium is a potential environmental contaminant that causes adverse effects on the environment and the health of living organisms. Therefore, designing a simple and economic technique for its determination is very important. In this respect, a potentiometric sensor based on nefazodone as the ionophore and [BMIM]PF6 as the ionic additive were developed for the determination of ultra-trace amounts of cadmium (II),.

In this study, a new membrane ion selective electrode was constructed with a composition entailed of 10% nefazodone, 2% [BMIM]PF6, 30% PVC and 58% dioctyl phthalate (DOP).The created potential discrepancy between the membrane and reference electrodes was used as a signal which demonstrates a direct relationship with the logarithmic concentration of cadmium (II) for  its determination.

The constructed sensor showed an appropriate Nernstian slope (30.5 mV. Decade-1) in a wide concentration range (1×10-9 - 8×10-2 M) with the detection limit of 6×10-9 M. The electrode potential was pH-independent in the range of 3.5-8.0. The response time and lifetime of the electrode obtained 5 s and 15 weeks, respectively.

The constructed sensor independent of sample preparation was employed successively for the measurement of low concentrations of cadmium (II) in the environmental samples .Moreover,  the obtained findings were in a good agreement with the results of flame atomic absorption spectroscopy. Therefore, the designed electrode established pinpoint accuracy and it can be used for the determination of cadmium (II) in aqueous samples.

Silver is a toxic heavy metal that is used in various industries and has adverse effects on both human health and the environment. In this respect its determination with sensitive and economic analytical methods is of great importance.

In this research, a novel ion selective electrode based on perphenazine as an ionophore was developed for determination of Ag+. The optimum composition that showed the highest sensitivity was constructed by mixing 9% ionophore, 2% NaTPB as ionic additive, 59% DOP as the plasticizer and 30% PVC.

The designed sensor showed a linear response over the concentration range of 1×10-6-1×10-2 M with the slope of 60.3 mV/Decade. The detection limit of the electrode was obtained 9×10-7 M. The response time and lifetime of the proposed sensor were 5 seconds and 10 weeks, respectively. The selectivity of electrode was evaluated by matched potential method and no serious interference was observed.

In the end, the sensor applicability in determination of Ag+ in three waste water specimens as real samples was evaluated and the good agreement between the results of sensor and the results of flame atomic absorption spectroscopy showed the designed electrode has enough accuracy and it can be used for determination of Ag (I) in the aqueous environmental samples. In conclusion, finally the performance of the prepared sensor in determining the amount of silver ions in three effluent samples was evaluated as the real samples. The results were in good agreement with those obtained by flame atomic absorption method which indicates that the designed sensor can be successfully employed in the accurate determination of silver (I) in environmental aqueous samples.

Reactive black 5 is a toxic dye that has adverse effects on the environmental ecosystems and the health of human beings. Therefore, its removal is very important. Among the reported methods adsorption gathered a huge attention in the recent years because of its simplicity and low-cost. In this review paper, removal of reactive black 5 by adsorption method from waste waters was evaluated and all of the achievements from the past to the present were discussed in detail. The influence of important operational parameters on the adsorption efficiency of reactive black 5 such as pH, temperature, adsorbent dosage and initial dye concentration was investigated. In addition, the reported adsorbents for reactive black 5 were divided into different groups on the basis of their nature (like nanostructures, natural materials, by products and chitosan based adsorbents) and their important characteristics, including adsorption capacity, removal percentage, initial dye concentration, repeatability, the synthesis cost and optimized experimental parameters are compared with each other in detail. Moreover, important conclusions have been made from the surveyed literature and some suggestions are proposed for the future works.

In this research study, the detection and removal of nalidixic acid by boron nitride nanocluster (B12N12) were investigated using the DFT, infra-red (IR), natural bond orbital (NBO) and frontier molecular orbital (FMO) computations. The calculated negative values of adsorption energy, Gibbs free energy changes, and great amounts of thermodynamic equilibrium constants demonstrated nalidixic acid adsorption on the surface of B12N12 was spontaneous, irreversible and experimentally feasible. The values of adsorption enthalpy changes and specific heat capacity (CV) revealed that, the interaction of the adsorbate and adsorbent was exothermic and B12N12 was an ideal nanostructure for the construction of new thermal sensors for detection of nalidixic acid. The influence of temperature on the thermodynamic parameters was also investigated and the results demonstrated that, the adsorption process was more favorable at room temperature. The NBO results indicated in all of the studied configurations covalent bonds were formed between nalidixic acid and B12N12 and their interaction was chemisorption. The density of states (DOS) spectrums showed that, the bandgap of boron nitride nanocage after the adsorption of nalidixic acid decreased from 14.864 (eV) to 7.314 (eV), indicating that the electrical conductivity of B12N12 improved significantly in the adsorption process and B12N12 is an appropriate sensing material for developing novel electrochemical sensor to nalidixic acid determination. The important structural parameters including chemical hardness, chemical potential, dipole moment, electrophilicity and maximum charge capacity were also computed and discussed in detail.

In this research, the performance of boron nitride nanocone for the detection and removal of ampicillin was investigated by infra-red (IR), natural bond orbital (NBO), frontier molecular orbital (FMO) computations. The calculated values of adsorption energy showed the interaction of ampicillin with BN nanocone is experimentally possible. The calculated values of Gibbs free energy and thermodynamic equilibrium constant showed the adsorption process is spontaneous and irreversible. The calculated values of enthalpy changes and specific heat capacity showed ampicillin adsorption is exothermic and BN nanocone can be used for the construction of a new thermal sensor for the detection of ampicillin. The effect of temperature on the thermodynamic parameters was also evaluated and the results indicated ampicillin adsorption is more favorable in room temperature. The NBO results demonstrated in both of the studied configurations a monovalent chemical bond is formed between the nanostructure and the adsorbate and the interaction process is chemisorption. The DOS spectrums showed the bandgap of BN nanocone increased from 1.888 (eV) to 7.030 (eV) which proved this nanomaterial is an appropriate electrochemical sensing material for detection of ampicillin. Some important structural parameters such as dipole moment, electrophilicity, maximum charge capacity, chemical hardness and chemical potential were also calculated and discussed in detail.

Quantitative structure-activity relationship (QSAR) analysis has been carried out with a series of 107 anti-HIV HEPT compounds with antiviral activity, which was performed by chemometrics methods. Bi-dimensional images were used to calculate some pixels and multivariate image analysis was applied to QSAR modelling of the anti-HIV potential of HEPT analogues by means of multivariate calibration, such as principal component regression (PCR) and partial least squares (PLS). In this paper, we investigated the effect of pixel selection by application of genetic algorithms (GAs) for the PLS model. GAs is very useful in the variable selection in modelling and calibration because of the strong effect of the relationship between presence/absence of variables in a calibration model and the prediction ability of the model itself. The subset of pixels, which resulted in the low prediction error, was selected by genetic algorithms. The resulted GA-PLS model had a high statistical quality (RMSEP = 0.0423 and R2 = 0.9412) in comparison with PCR (RMSEP = 0.4559, R2 = 0.7929) and PLS (RMSEP = 0.3275 and R2 = 0.0.8427) for predicting the activity of the compounds. Because of high correlation between values of predicted and experimental activities, MIA-QSAR proved to be a highly predictive approach.