Electrocatalytic Oxidation and Determination of Insulin at Rhodamine B –Multi-walled Carbon Nanotubes Modified Glassy Carbon Electrode

AbstractThe modified electrode surface was provided with the electropolymerization of the rhodamine B in the presence of carbon nanotube (CNT). The modified electrode offers dramatic improvements in the stability and sensitivity of voltammetric measurements of insulin compared to the bare and rhodamine B modified glassy carbon electrodes. The enhanced electrocatalytic activity towards insulin is indicated from lowering the potential of the oxidation process (starting around 0.75 vs. Ag/AgCl) and the substantially higher sensitivity over the entire potential range. A linear dynamic range (100–600nM) was achieved with a detection limit of 5nM. The accuracy of the modified electrode was indicated by insulin recovery test in the real samples as human plasma and pharmaceutical samples

Application of Modified Magnetite Nanoparticles as a New Sorbent for Separation/Preconcentration of Mercury(II) Trace Amounts and its Determination by Cold Vapor Atomic Absorption Spectrometry

A new, simple, fast and reliable method has been developed to separation/preconcentration of trace amounts of mercury ions using dithizone/sodium dodecyl sulfate-immobilized on alumina-coated magnetite nanoparticles (DTZ/SDS-ACMNPs) and its determination by cold vapor atomic absorption spectrometry (CVAAS). This method avoided the time-consuming column-passing process of loading large volume samples in traditional solid phase extraction (SPE) through the rapid isolation of DTZ/SDS-ACMNPs with an adscititious magnet. Under the optimal experimental conditions, the enrichment factor, detection limit, linear range and relative standard deviation (RSD) of Hg(II) ions were 250 (for 500 mL of sample solution), 0.058 µg mL–1, 0.2–80.0 µg mL–1 and 3.55 % (for 5.0 µg mL–1, n=10), respectively. The adsorbed mercury ions were quantitatively eluted by 2.0 mL of 0.4 mol L–1 HBr solution. The pre¬sented procedure was successfully applied for determination of mercury content in the different samples of water and blood

Determination of silver(I) by flame atomic absorption spectrometry after separation/preconcentration using modified magnetite nanoparticles

AbstractA new, simple, fast and reliable method has been developed for the separation/preconcentration of trace amounts of silver ions using 2-mercaptobenzothiazole/sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (MBT/SDS-ACMNPs) and their determination by flame atomic absorption spectrometry (FAAS). Optimal experimental conditions, including pH, sample volume, eluent concentration and volume, and co-existing ions, have been studied and established. Under optimal experimental conditions, the enrichment factor, detection limit, linear range and relative standard deviation (RSD) of Ag(I) ions were 250 (for 500 mL of sample solution), 0.56 ng mL−1, 2.0–100.0 ng mL−1 and 3.1% (for 5.0 μg mL−1, n=10), respectively. The presented procedure was successfully applied for determination of silver content in the different samples of water

Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs) followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V) after oxidation of As(III) to As(V) using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III) was calculated by subtracting the concentration of As(V) from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD) of arsenate were 175 (for 350 mL of sample solution), 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1, n=7), respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained