Time filter

Source Type

Shamsipur M.,Razi University | Fattahi N.,Razi University | Fattahi N.,Kermanshah University of Medical Sciences | Assadi Y.,Daana Pharmaceutical Company | And 2 more authors.
Talanta | Year: 2014

A solid phase extraction (SPE) coupled with dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) method, using diethyldithiphosphate (DDTP) as a proper chelating agent, has been developed as an ultra preconcentration technique for the determination of inorganic arsenic in water samples prior to graphite furnace atomic absorption spectrometry (GFAAS). Variables affecting the performance of both steps were thoroughly investigated. Under optimized conditions, 100 mL of As(ΙΙΙ) solution was first concentrated using a solid phase sorbent. The extract was collected in 2.0 mL of acetone and 60.0 μL of 1-undecanol was added into the collecting solvent. The mixture was then injected rapidly into 5.0 mL of pure water for further DLLME-SFO. Total inorganic As(III, V) was extracted similarly after reduction of As(V) to As(III) with potassium iodide and sodium thiosulfate and As(V) concentration was calculated by difference. A mixture of Pd(NO3)2 and Mg(NO 3)2 was used as a chemical modifier in GFAAS. The analytical characteristics of the method were determined. The calibration graph was linear in the rage of 10-100 ng L-1 with detection limit of 2.5 ng L-1. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 80 ng L-1 of As(ΙΙΙ) were 6.8% and 7.5%, respectively. The method was successfully applied to speciation of As(III), As(V) and determination of the total amount of As in water samples and in a certified reference material (NIST RSM 1643e). © 2014 Elsevier B.V. Source

An ultra-preconcentration technique composed of solid-phase extraction (SPE) and dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-flame photometric detection (GC-FPD) was used for determination of thirteen organophosphorus pesticides (OPPs) including phorate, diazinon, disolfotane, methyl parathion, sumithion, chlorpyrifos, malathion, fenthion, profenphose, ethion, phosalone, azinphose-methyl and co-ral in aqueous samples. The analytes were collected from large volumes of aqueous solutions (100mL) into 100mg of a SPE C 18 sorbent. The effective variables of SPE including type and volume of elution solvent, volume and flow rate of sample solution, and salt concentration were investigated and optimized. Acetone was selected as eluent in SPE and disperser solvent in DLLME and chlorobenzene was used as extraction solvent. Under the optimal conditions, the enrichment factors were between 15,160 and 21,000 and extraction recoveries were 75.8-105.0%. The linear range was 1-10,000ngL -1 and limits of detection (LODs) were between 0.2 and 1.5ngL -1. The relative standard deviations (RSDs) for 50ngL -1 of OPPs in water with and without an internal standard, were in the range of 1.4-7.9% (n=5) and 4.0-11.6%, respectively. The relative recoveries of OPPs from well and farm water sat spiking levels of 25 and 250ngL -1 were 88-109%. © 2011 Elsevier B.V. Source

Aghazadeh M.,Islamic Azad University | Badali M.,Islamic Azad University | Badali M.,Daana Pharmaceutical Company | Baradarani M.M.,Urmia University
Chimica Oggi/Chemistry Today | Year: 2016

Reaction of 5-bromo-3-(1-methylpyrrolidine)ylidene-3H-indole with methyl iodide or acetic anhydride, followed in each case by base, leads to the formation of 3-keto indoles. The reaction of this ylidene-3H-indole with acidic methylene compounds such as 1-phenylbutane-1,3-dione and malononitrile led to the formation of azepine and carbazole containing systems. Source

Jamali M.R.,Payame Noor University | Assadi Y.,Daana Pharmaceutical Company | Rahnama Kozani R.,Payame Noor University
Journal of Chemistry | Year: 2013

A simple, rapid, and powerful microextraction technique was used for determination of palladium (II) ion in water samples using dispersive liquid-liquid microextraction (DLLME) followed by graphite furnace atomic absorption spectrometry (GF AAS). The different variables affecting the complexation and extraction conditions such as extraction and disperser solvent type, extraction time, pH, and concentration of chelating agent were optimized. Under the optimum conditions, the calibration graph was linear in the ranges of 0.05-1 μg L -1 with detection limit of 0.02 μg L -1. The precision (RSD ) for ten replicate determination at 0.2 μg L -1 of palladium was better than 3.5 and the enrichment factor 166.5 was obtained from only 5.0 mL of sample. Under the presence of foreign ions, no significant interference was observed. Finally, accuracy and application of the method were estimated by using test samples of natural waters spiked with different amounts of palladium. © 2013 Mohammad Reza Jamali et al. Source

Majidi M.R.,University of Tabriz | Asadpour-Zeynali K.,University of Tabriz | Hafezi B.,University of Tabriz | Hafezi B.,Daana Pharmaceutical Company
Analytical Methods | Year: 2011

A copper hexacyanoferrate nanostructure was prepared on the surface of a disposable pencil graphite electrode. The copper hexacyanoferrate nanostructures showed a pair of symmetric voltammetric peaks at 0.67 V/SCE. An electrochemical comparative characterization between copper hexacyanoferrate nano and bulk structures was presented. The transfer coefficient (α) and apparent charge rate constant (Ks) were evaluated for each of copper hexacyanoferrate nano and bulk structures. The resulting electrode exhibits an excellent electrocatalytic activity for the oxidation of ceftriaxone sodium. Cyclic voltammetry and chronoamperometry were employed to characterize the response to ceftriaxone sodium that changes linearly in the concentration range from 2 to 72 μM, with a detection limit of 0.54 μM (at a signal to noise ratio of 3). Typical features of the sensor include low cost, simple preparation, fast response, good stability, selectivity, and reproducibility. It was applied to the determination of ceftriaxone sodium in pharmaceutical samples. All results obtained were compared to the recommended procedure by British Pharmacopeia. © 2011 The Royal Society of Chemistry. Source

Discover hidden collaborations