Search

In this study, ZnO- Red Ochre nanocomposite was green synthesized by Rosa Damascena (RD) extract (RD Z RO NCs). Proton Induced X-ray Emission microanalysis (Micro-PIXE) and X-ray diffraction (XRD) pattern confirmed the presence of hematite (Fe 2 O 3), and quartz (SiO 2) mineral phases in the Red Ochre (RO) nanoclay. In addition, the XRD pattern shows the ZnO, ZnFe 2 O 4 , SiO 2 , Fe 2 O 3 , and Si phases in the RD Z RO NCs that were green synthesized with natural RD extract and RO. The RD Z RO NCs were used to modify the carbon paste electrode (CPE) for the electrochemical determination of the anticancer drug 5-fluorouracil (5-FU). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were employed to investigate the surface behavior of modified CPE (RD Z RO NCs/CPE). The electrochemical behavior of 5-FU at the RD Z RO NCs/CPE was exanimated by CV, differential pulse voltammetry (DPV), chronoamperometry (CA), and chronocoulometry (CC). Based on the DPV technique, a linear relationship between peak current and concentration of 5-FU was obtained in the dynamic range of 0.05–140.0 μM and with a detection limit equal to 0.0016 μM. The selectivity of RD Z RO NCs/CPE for 5-FU was studied in the presence of different inorganic and organic species. Also, the content of 5-FU was measured in real samples by RD Z RO NCs/CPE. [ABSTRACT FROM AUTHOR]

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for preconcentration and determination of tramadol, ((±)-cis-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol-HCl), in aqueous and biological samples (urine, blood). DLLME is a simple, rapid and efficient method for determination of drugs in aqueous samples. Efficient factors on the DLLME process has defined and optimized for extraction of tramadol including type of extraction and disperser solvents and their volumes, pH of donor phase, time of extraction and ionic strength of donor phase. Based on the results of this study, under optimal conditions and by using 2-nitro phenol as internal standard, tramadol was determined by GC-MS, and the figures of merit of this work were evaluated. The enrichment factor, relative recovery and limit of detection were obtained 420, 99.2% and 0.08 μg L-1, respectively. The linear range was between 0.26 and 220.00 μg L-1 (R² = 0.9970). The relative standard deviation for 50.00 μg L-1 of tramadol in aqueous samples by using 2-nitro phenol as IS was 3.6% (n = 7). Finally, the performance of DLLME was evaluated for analysis of tramadol in urine and blood. [ABSTRACT FROM AUTHOR]

The non-enzymatic voltammetric and amperometric detection of glucose using a palladium coated nanoporous gold film electrode is described. The effect of surfactant on the fabrication of nanoporous gold film was also investigated. The voltammetric detection of glucose was performed by cyclic voltammetry. The sensor had good electrocatalytic activity towards oxidation of glucose, exhibited a rapid response (,6 s), and gave a linear range from 1 to 33 mM with a detection limit of 5 ΜM (with a signal to noise ratio of 3). The wide dynamic range, long-term stability, high sensitivity and selectivity, good reproducibility, and high resistance towards electrode fouling resulted in an ideal inexpensive amperometric glucose biosensor applicable for complex matrices. [ABSTRACT FROM AUTHOR]

Abstract: Polyoxometalates (POM) supported on zirconia, H3PW12O40/ZrO2, were prepared by incorporating polyphosphotungstate into a zirconia matrix via sol–gel technique that involving the hydrolysis of zirconium (IV) n-butoxide, Zr (n-OBu)4, as the ZrO2 source. This insoluble and readily separable catalyst was characterized by using XRD, FT-IR, SEM, and UV diffuse reflectance spectroscopy (UV-DRS), indicating that the polyphosphotungstate was chemically attached to the zirconia supports, and primary Keggin structure remained intact. The photocatalytic and sonocatalytic activity of the supported polyphosphotungstate was tested via degradation of different dyes in aqueous solutions. The POM–ZrO2 nanocomposite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure ZrO2. [Copyright &y& Elsevier]

The authors have modified a carbon paste electrode with Al2O3-supported palladium nanoparticles (PdNP@Al2O3) to obtain a sensor for simultaneous voltammetric determination of melatonin (MT), dopamine (DA) and acetaminophen (AC). The PdNP@Al2O3 was characterized by scanning electron microscopy and energy-dispersive X-ray spectra. The sensor can detect DA, AC, MT and their mixtures by giving distinct signals at working voltages of typically 236, 480 and 650 mV (vs. Ag/AgCl), respectively. Differential pulse voltammetric peak currents of DA, AC and MT increase linearly in the 50 nmol L−1 - 1.45 mmol L−1, 40 nmol L−1 -1.4 mmol L−1, and 6.0 nmol L−1 - 1.4 mmol L−1 concentration ranges. The limits of detection are 36.5 nmol L−1 for DA, 36.5 nmol L−1 for AC, and 21.6 nmol L−1 for MT. The sensor was successfully used to detect the analytes in (spiked) human serum and drug samples. [ABSTRACT FROM AUTHOR]

A solid phase extraction procedure is proposed for the separation and preconcentration trace amounts of Pd (II) in aqueous medium by using a column of multi-walled carbon nanotubes (MWCNTs) modified with 1-(2-pyridylazo)-2-naphtol (PAN). The elution was carried out with 5.0mL of 2mol L-1 thiourea in 4mol L-1 HCl. The amount of eluted Pd (II) was measured using flame atomic absorption spectrometry. The influences of the various experimental parameters, including pH, eluent type, concentration of eluent, amount of sorbent, and interfering ions on the recovery of palladium ions were investigated. The detection limit for palladium under the optimum condition was 1.0 ngmL-1 with enrichment factor of 100 and the relative standard deviation was 1.89% (n =6, C = 0.5 μgmL-1). The method was applied for the determination of Pd (II) in water samples. The enrichment performance of the method using modified MWCNTs as preconcentration sorbent was also compared with PAN-modified activated carbon. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POM) supported on zirconia, H(3)PW(12)O(40)/ZrO2, were prepared by incorporating polyphosphotungstate into a zirconia matrix via sol-gel technique that involving the hydrolysis of zirconium (IV) n-butoxide, Zr (n-OBu)(4), as the ZrO(2) source. This insoluble and readily separable catalyst was characterized by using XRD, FT-IR, SEM, and UV diffuse reflectance spectroscopy (UV-DRS), indicating that the polyphosphotungstate was chemically attached to the zirconia supports, and primary Keggin structure remained intact. The photocatalytic and sonocatalytic activity of the supported polyphosphotungstate was tested via degradation of different dyes in aqueous solutions. The POM-ZrO(2) nanocomposite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure ZrO(2)., (Copyright © 2011 Elsevier B.V. All rights reserved.)