THIS WORK DEALS WITH SEVERAL DIRECT AND INDIRECT SPECTROPHOTOMETRIC, SPECTROFLUORIMETRIC AND VOLTAMMETRIC ANALYSES OF THE VASODILATOR DRUG: naftidrofuryl oxalate (NF). For the derivative spectrophotometric measurement, NF was determined by measuring the peak to peak amplitude of (1)D263-299 and (2)D282-311 or the absolute peak height of (1)D237 and (2)D241, while its reaction product with conce...

Nitrogen (N) and sulfur (S) co-doped activated graphene (N,S-AGR) was prepared by the one-pot pyrolysis of a mixture of graphene oxide (GO), thiourea, and potassium hydroxide (KOH), where thiourea acts as the source of N and S dopants and KOH is the activator for porosity. N,S-AGR with a dopant abundance of 2.8 at% N and 2.3 at% S was then used as a high-activity electrocatalyst in the fabricat...

We report the simultaneous determination of two neurotransmitters, norepinephrine (NEP) and serotonin (5-HT), at physiological pH using the electropolymerized film of 3-amino-5-mercapto-1,2,4-triazole modified glassy carbon (p-AMTa) electrode. A bare glassy carbon (GC) electrode fails to resolve the voltammetric signals of NEP and 5-HT due to the surface fouling caused by the oxidized products ...

Glassy carbon electrodes coated with Nafion are used for the ion-exchange voltammetric (IEV) determination of Fe(II) in the pore-waters and acidic extracts of sediments of the lagoon of Venice (Italy). The coated electrodes give reversible voltammetric signals, well resolved from background currents, which can be used for quantitative determinations. The yield of iron extracted by HCl from the ...

In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetri...

A sensitive and selective procedure is presented for the voltammetric determination of cobalt. The procedure involves an adsorptive accumulation of cobalt Pyrogallol Red (PGR) complex on a stationary mercury drop electrode, followed by cathodic stripping voltammetry measurement of the reduction current of the adsorbed complex at –1.17 V (vs. Ag/AgCl). The optimum conditions for the determinatio...

Determination of selenium in biological and environmental samples is usually difficult due to its trace or ultra-trace quantities, pre-concentration stages, destruction of organic matrices by acid digestion and oxygen plasma combustion followed by separation from interfering metal ions such as ion exchange separation, solvent extraction or hydride generation. Selective separation of selenium is...

In this paper, a pencil graphite electrode was pretreated using chronoamperometry technique in phosphate buffer solution (pH=7.0) for sensitive determination of quercetin. Oxidation of quercetin was investigated using pretreated pencil graphite electrode and anodic stripping differential pulse voltammetry. Under optimal conditions, the anodic current of quercetin exhibited linear response to it...

The electronic conductivity of tri-n-octylphosphineoxide (TOPO)-protected CdSe quantum dots (QDs) was studied at the air-water interface using the Langmuir technique within the context of photochemical and photophysical excitation. It was found that, upon photoirradiation with photon energies higher than that of the absorption threshold, the voltammetric currents increased rather substantially ...

A method for the determination of food additive vanillin was developed by adsorptive stripping voltammetry. Its determination was carried out at the anodically pre-treated boron-doped diamond electrode in aqueous solutions. Using square-wave stripping mode, the compound yielded a well-defined voltammetric response in phosphate buffer, pH 2.5 at +1.14 V (vs. Ag/AgCl) (a pre-concentration step be...