Voltammetric determination of hydroxylamine in water and waste water samples using a NiO nanoparticle/new catechol derivative modified carbon paste electrode

A (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol (DED) mo­di­fied NiO/NPs carbon paste electrode “(DED/NiO nanoparticle (NiO/NPs)/CPE) was constructed for determination of hydroxylamine (HX). The cyclic voltammogram showed that the electro­catalytic oxidation of HX at the surface of DED/NiO/NPs/CPE occurs at a potential of about 800 mV less positive than with an unmodified electrode. Square-wave voltammetry results presented that the electrocatalytic oxidation peak currents of HX in pH 8.0 had two linear dynamic ranges in the range of 0.1 to 2.0 and 2.0 to 400.0 µM HX, with a detection limit of 0.07 µM. The kinetic parameters such as electron transfer coefficient a (0.47) and rate constant (2.454 × 103 M-1 s-1) were determined for the chemical reaction between HX and DED. Finally, this method was evaluated for the determination of HX in water and waste water samples

Determination of 6-Mercaptopurine Anticancer Drug

A novel and sensitive biosensor employing immobilized DNA on a pencil graphite electrode modified with polypyrrole/functionalized multiwalled carbon nanotubes for the determination of 6-mercaptopurine (6-MP) is presented. In the first step, we modified the pencil graphite surface with polypyrrole and functionalized multiwalled carbon nanotubes (MWCNT/COOH). The developed electrode was characterized by scanning electron microscopy, atomic force microscopy, reflectionabsorption infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In the other step, we used decreases in the oxidation responses of guanine and adenine as a sign of the interaction of 6-MP with salmon sperm double-stranded DNA using differential pulse voltammetry. The signal of guanine oxidation was linear with respect to the 6-MP concentration in the range of 0.2-100 mu mol L-1 with a detection limit of 0.08 mu mol L-1. The modified electrode was utilized for the determination of 6-MP in real samples