فهرست مطالب

  • Volume:2 Issue: 2, 2015
  • تاریخ انتشار: 1394/10/01
  • تعداد عناوین: 8
|
  • Maryam Fayazi, Mohammad Ali Taher, Daryoush Afzali, Ali Mostafavi Pages 73-84
    In the present study, removal of dibenzothiophene (DBT) from model oil (n-hexane) was investigated using magnetic activated carbon (MAC) nano-composite adsorbent. The synthesized nano-composite was characterized by FT-IR, FE-SEM, BET and VSM techniques. The MAC nano-composite exhibited a nearly superparamagnetic property with a saturation magnetization (Ms) of 29.2 emu g-1, which made it desirable for separation under an external magnetic field. The magnetic adsorbent afforded a maximum adsorption capacity of 38.0 mg DBT g-1 at the optimized conditions (adsorbent dose, 8 g l-1; contact time, 1 h; temperature, 25 °C). Langmuir, Freundlich and Temkin isotherm models were used to fit equilibrium data for MAC nano-composite. Adsorption process could be well described by the Langmuir model. Kinetic studies were carried out and showed the sorption kinetics of DBT was best described by a pseudo-second-order kinetic model. In addition, the MAC nano-composite exhibited good capability of recycling to adsorb DBT in gasoline deep desulfurization.
    Keywords: Magnetic, Desulfurization, Activated Carbon, adsorbent, Dibenzothiophene
  • Somayeh Makarem, Ali Reza Fakhari, Ali Asghar Mohammadi Pages 85-89
    Aza heterocyclic compounds are major interest for organic chemists because of their mainly pharmacological activities and clinical applications such as antianxiety, antitumor, anticonvulsant, cardiotonic and vasorelaxant. This contribution describes an electrochemical approach for the preparation of nanosized particles of phthalazine in high yields and very short reaction time. The method is based on theone-pot multicomponent reaction (MCRs) of phthalhydrazide, malononitrile and aldehydes in propanol employing undivided cell in the presence of NaBr as an electrolyte. The product was characterized, after purification, using IR, 1H NMR, 13C NMR, MS and SEM. This procedure provides a method by which nanoparticles are synthesized directly from phthalhydrazide, malononitrile and aldehydes insides of a routine protocol for the synthesis of nano particles of organic compounds in which the synthesized organic compound is transformed into nanosized particles using modern high technology, for example ultrahighpressure rapid expansion of supercritical solution, and supercritical antisolvent with enhanced mass transfer. Size reduction is a fundamental unit operation having important applications in pharmacy. It helps to improve solubility and bioavailability, reduce toxicity, enhance release, and provide better formulation opportunities for drugs.
    Keywords: Phthalhydrazide, Malononitrile, Aldehydes, Nanosized particles, Multicomponent
  • Hossein Soltani, Mohammad Reza Yaftian, Abbasali Zamani, Massomeh Ghorbanloo Pages 91-98
    A new carboxylic acid extractant, named 2-(dibutylcarbamoyl)benzoic acid, is prepared and its potential for selective solvent extraction and recovery of lead ions from industrial samples was investigated. The slope analysis indicated that the lead ions are extracted by formation of 1:2 metal to ligand complexes. The effect of the parameters influencing the extraction efficiency including kind of the organic diluent, extractant concentration, type of the salt used for ionic strength adjustment, contact time and temperature was evaluated and discussed. Under optimized conditions (aqueous phase: 5 ml, initial lead concentration 1 × 10-4 M, pH 4, sodium chloride 0.1 M; organic phase: 5 ml dichloromethane, ligand concentration 0.05 M), a quantitative (75.2 ± 0.8%) and highly selective extraction of lead ions in the presence of zinc, nickel, cobalt and cadmium ions (each 1 × 10-4 M) was achieved, after 20 min. magnetically stirring of the phases, at 25 °C. The extracted lead ions were stripped from the organic phase by diluted nitric acid (0.1 M) solution. The proposed method was successfully applied for separation of lead from industrial samples. The study of the effect of temperature allowed evaluating the thermodynamic parameters of the extraction process of lead ions by the studied extractant into dichloromethane.
    Keywords: Lead ions, Solvent extraction, Selective separation, Carboxylic acid extractant, Industrial samples
  • Priyanka Bose, Suddhasattya Dey, Souvik Basak, Shreya Shah, Anjan De Pages 99-112
    The present study describes a simple, accurate, precise and cost effective UV-Vis Spectroscopic and RP-HPLC method for the estimation of Ibandronate sodium (IBN). The determination of Ibandronate sodium (IBN) was performed by both UV and RP-HPLC method using 215 nm as the determination wavelength. The drug was dissolved in NaOH solution (0.1N NaOH) for estimation in UV and in distilled water for the estimation in RP-HPLC using mobile phase 0.01 M Sodium dihydrogen phosphate (NaH2PO4): Acetonitrile (80:20), pH being adjusted to 3.3 with 10% ortho-phosphoric acid. A linear response was observed in the range of 10-50 μg ml-1 (R2 = 0.9981) for UV-Spectroscopy, whereas for RP-HPLC the linear response was observed in the range of 20-70 μg ml-1 (R2 = 0.9965). The limits of quantitation (LOQ) were estimated as 0.1 μg ml-1 and 0.05 μg ml-1, respectively for UV and RP-HPLC respectively. The recoveries of IBN from the marketed formulation were found to be within 100 ± 2% by both the methods. These methods were then effectively applied for the estimation of Boniva (tablet) and the results were obtained according to nominal content. The statistical analysis revealed that there is no significant difference (p > 0.05) between UV and HPLC methods regarding validation parameters and assay content.
    Keywords: Ibandronate sodium (IBN), UV-Vis spectroscopy, RP-HPLC, Calibration curve, LOD
  • Leila Fotouhi, Azamosadat Meshkani, Melody Houshmand Pages 113-118
    The aim of this study was to evaluate the utility of a proficiency testing program among limited number of local laboratories as an alternative to the IUPAC/CITAC guide on proficiency testing with a limited number of participants, specially where international schemes are not accessible. As a sample scheme we planned to determine aflatoxins (B1, G1, B2, G2, total) in Iranian pistachio matrix. A part of naturally contaminated pistachio sample was tested for sufficient homogeneity by a competent laboratory and then homogenized sub-samples were distributed among participants all across the country. The median of participants’ results was selected as assigned value. Student t-test was applied to show there is no significant difference between assigned and mean values of homogeneity test results obtained by the competent laboratory. Calculated z-scores showed that 6 out of 8 results in aflatoxin B1, 7 out of 8 results in aflatoxin B2, 5 out of 8 results in aflatoxin G1, 7 out of 8 results in aflatoxin G2 and 6 out of 9 results in aflatoxin total were in satisfactory range. Together our studies indicate that the approach described here is highly cost efficient and applicable for quality assurance of test results when there is no access to international proficiency testing providers.
    Keywords: Proficiency testing, Aflatoxins, Z, score, Pistachio, quality assurance, Assigned value
  • Naveen M. Gokavi, Sharanappa T. Nandibewoor Pages 119-128
    The voltammetric behaviour of Sulfadoxine (SDN) was studied at a glassy carbon electrode in 0.2 M phosphate buffer solutions using cyclic, differential-pulse (DPV) and square wave voltammetry (SWV). The dependence of the current on pH, concentration, and scan rate was investigated to optimize the experimental conditions for the determination of SDN. The oxidation process was shown to be diffusion controlled, irreversible over the pH range from 3.0-9.2. An analytical method was developed for the determination of SDN in phosphate buffer solution at pH 3.0 as a supporting electrolyte. A DPV method showed a good linear response as compared to SWV. The anodic peak current varied linearly with SDN concentration in the range 0.310-4.34 µg ml-1 of SDN with a limit of detection (LOD) of 0.01 µg ml-1. The recovery was determined in the range from 95.6-100.1%. The proposed method was successfully applied to the quantitative determination of SDN in pharmaceutical formulations and an urine as real samples.
    Keywords: Glassy carbon electrode, Sulfadoxine, Voltammetry, Phosphate buffer
  • Masoud Shariati, Rad, Mohsen Irandoust, Sara Sheikhi Pages 129-137
    Prediction using pure standards is expected to be biased whenever the slope of the calibration is affected by the presence of sample matrix. Moreover, in the presence of unknown spectral interferents, first-order algorithms like partial least squares cannot be used. In this study, a method for determination of carvedilol (CAR) in tablet and urine samples is proposed by excitation-emission fluorescence spectroscopy (EEM). The multivariate curve resolution-alternating least-squares (MCR-ALS) coupled with trilinearity constraint exploiting the second order advantage is applied for the analysis of EEMs. Moreover, the combination of standard addition with MCR-ALS was used to correct the matrix effect. Indeed, by the proposed strategy, both matrix effect and the problem of the presence of unknown interferents in determination of CAR are overcome.The MCR-ALS method was applied on EEMs under non-negativity and trilinearity constraints. For both samples, CAR was quantified at low mg l-1 level with an overall prediction error of -3.1% and -4.0% in urine and tablet samples, respectively.
    Keywords: Carvedilol, Excitation-emission fluorescence, Multivariate curve resolution, Urine samples
  • Molla Tefera, Shimelis Admassie, Merid Tessema, Solomon Mehretie Pages 139-150
    A sensor, based on multi-wall carbon nanotubes modified glassy carbon electrode (MWCNT/GCE), was developed for determination of fenitrothion. Determining the surface area of MWCNT/GCE showed that this surface is three times more active than that of a glassy carbon electrode. The experimental parameters, such as the amount of MWCNTs, pH of the fenitrothion solution, preconcentration potential and preconcentration time were optimized. Under these conditions, reduction current showed a linear relationship with the concentration of fenitrothion in a range of 0.01-5.0 mM, with a detection limit of 6.4 nM. The modified electrode also exhibited good stability and reproducibility. The effects of possible interferents were studied and found to be negligible, indicative of high selectivity of the electrode. This sensor was also successfully employed for determination of fenitrothion in soil and Teff samples with recovery values in the range of 88.0-93.3% and 86.7-91.4%, respectively.
    Keywords: Fenitrothion, Multi, wall carbon nanotube, Square wave voltammetry, Soil, Teff