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One of the most important quinolones, Ofloxacin (OFX), was directly determined using a carbon paste electrode modified by MWCNT@Sm(OH)3 nanocomposite using fast Fourier transform square wave voltammetry. The prepared electrode showed a considerable current increase compared to a bare one. The electrode surface was thoroughly characterized using field emission scanning electron microscopy and electrochemical impedance spectroscopy. The maximum performance efficiency of the developed electrode was reached at a scan rate of 0.1 V s-1, phosphate buffer pH 8 while the electrode contained 7% of Sm(OH)3 nanoparticles and 5% of MWCNT in the entire paste. Based on the results, a wide linear range of response toward OFX concentration from 0.01 to 1.00 µM was obtained (frequency of 700 Hz, number of cycles 8, and amplitude of 20 mV) and the limit of detection of 0.8 nM was achieved on top. The proposed electrode also successfully identified OFX in some pharmaceutical formula as well with adequate sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

In the present paper, naltrexone determined at ultra-trace scale was performed by combining fast Fourier transform square wave admittance voltammetry with electromembrane extraction in urine samples. On this approach, a constructed three-microelectrode setup positioned at the upper end of the hollow fiber in a micro-pipette tip, which was then applied for the extracted analyte determination. The employed membrane was consisted 85% of 2-nitrophenyl octyl ether and 15% di-(2-ethylhexyl) phosphate immobilized in the pores of a hollow fiber. A DC potential of 150 V within the time of 25 min was applied, followed by the analytes migration from 1 mM HCl as the sample solution, through the supported liquid membrane into an acidic acceptor solution with pH 3.0 placed in the lumen of hollow fiber. Based on the obtained results, the introduced method exhibited one the linear range 5-1000 ng/mL (R2=0.993). Besides, the detection limit of 0.5 ng/mL was attained. Since the preconcentration factor was found to be 80 in the urine sample after the performed process, it can be concluded that the introduced method could be classified among qualified techniques for naltrexone detection in some complex samples. [ABSTRACT FROM AUTHOR]

In this study, several heavy metal ions (Zn2+, Pb2+ and Cd2+) were extracted and online determined in water samples by ultrasound-assisted hollow fiber liquid phase microextraction (HF-LPME) coupled with stripping fast Fourier transform continuous cyclic voltammetry (SFFTCCV) as a novel electroanalytical technique. Initially, the heavy metal ions were extracted through a polypropylene membrane soaked in xylene and bis(2-ethylhexyl)phosphoric acid (DEHPA), into an acceptor solution located in the lumen of a hallo fiber (HF). The analytes were then determined through an electrochemical approach using a micro carbon paste electrode (micro-CPE) as a working electrode placed into the upper end of the HF. The optimum conditions for the proposed method were reached at scan rate of 6 V s-1, stripping potential: 200 mV, stripping time: 5 s, the sample solution pH: 5, the acceptor solution pH: 4, extraction time under the ultrasound irradiation: 60 min, membrane composition: 0.5 M DEHPA in xylene. Limit of detection (LOD) and limit of quantification (LOQ) were determined to be in the range of 0.1-1 and 1-5 ng.mL-1. Furthermore, the recovery percentages of 87%, 62% and 41% were obtained for Zn2+, Pb2+ and Cd2+ ions, respectively. Based on the results, the method presented adequate potential to be used for the simultaneous determination of the stated analytes in the sea, river and well water samples, under optimal conditions. [ABSTRACT FROM AUTHOR]

In the present study, copper ion has been separated from Phosphate Buffer Solution by 2-Amino-N-(2-Pyridyl Methyl)-Benzamide as an organic ligand through a flat type Supported Liquid Membrane (SLM). To this end, the organic ligand was dissolved in various solvents, and then the Polytetrafluoroethylene (PTFE) membrane was immersed in the resulting solutions for 24 h. Before extraction step, solvents with best performances including Ethanol and benzyl acetate were selected as solvent and as plasticizer, respectively. The optimized complexing reagent concentration on the membrane was 0.05 M. The adjusted pH was 4.5 and concentration of Cu solution was 1×10-3 M for feed solution, respectively. Copper ion was then determined using Fast Fourier Transformation Continuous Stripping Cyclic Voltammetry (FFTCCV) technique by a Carbon Paste Electrode (CPE). PTFE with 0.1 μm pore size have more permeability than 0.2 μm. Based on the obtained results, effective parameters imposing sensitivity of copper ion measurement were finally investigated at pH 3.2, at scan rate of 10 mV.s-1, stripping time of 0.1s and potential of -600 mV. Limit of detection of 0.19 μM for copper ion in optimized condition was attained. Under the optimized conditions the recovery of Copper ions from real samples were studied and recovery percentage were 45.71%, 34.28% and 22.58% for tap water, river water and sea water respectively. [ABSTRACT FROM AUTHOR]