Simultaneous voltammetric determination of Adrenaline and Tyrosine in real samples by neodymium oxide nanoparticles grafted graphene.

Nd2O3 nanoparticle grafted graphene nanocomposite (NOGG) was synthesized by sonochemical treatment of an ethanolic dispersion of Nd2O3 nanoparticle and graphene. All the synthesized materials were characterized by XRD, FESEM, TEM, and BET. The NOGG has a high specific surface area (272 m2g-1) with narrowly distributed pores with diameter centered at 2.8, 6.0 and 7.50 nm. A composite paste electrode of 1:1 (w/w) NOGG and graphite was showed better electrochemical properties. The NOGG/GP electrode showed all around better electrocatalytic activity towards Adrenaline (AD) and Tyrosine (TY) than TRG/GP and bare GP electrode. According to cyclic voltammograms, AD and TY oxidized irreversibly through adsorption control process. DPV peak currents were measured at 378 ±â€¯15 mV and 787 ±â€¯15 mV for determination AD and TY respectively using the NOGG/GP electrode as the peak intensities were highest at those potentials. Under the optimized experimental condition, the determination ranges for AD and TY showed two linear ranges, those were 0.1-5-130 µM and 0.1-3-120 µM, respectively. A detection limit of AD and TY was measured (m-LOD) to be 50 nM and 40 nM, respectively. The modified electrode was reproducible, selective, highly sensitive and also employed for analysis of AD and TY in biological and pharmaceutical samples with excellent recovery.

Sol-gel synthesis of cubic titanium dioxide nanoparticle using poly(ethylene glycol) as a capping agent: voltammetric simultaneous determination of uric acid and guanine.

Titanium dioxide nanoparticles (NPs) were synthesized by a sol-gel method from hexafluorotitanic acid using poly(ethylene glycol) as a capping agent. The crystal structure and morphology of the NPs were characterized by X-ray diffraction, FESEM, and TEM. The NPs were used to modify a graphite paste electrode for simultaneous determination of uric acid (UA) and guanine (GU). The effect of calcination temperature on crystal structure and electrocatalytic activity was investigated. The electrochemical responses to UA and GU at bare GP, TiO2-350/GP, and TiO2-600/GP electrodes were compared. The DPV oxidation peaks of UA and GU were found to be strongest at around 304 and 673 mV, respectively, against Ag/AgCl reference electrode, and this are well separated for effective simultaneous determination. UA and GU can be simultaneously determined by this method. Response is linear within the range 0.1-500 µM and 0.1-40 µM for UA and GU, respectively. The detection limits are 70 nM for UA and 50 nM for GU (at an S/N  ratio of 3). The TiO2-600/GP electrode showed excellent analytical performance when analyzing spiked urine and serum samples. Graphical abstract A graphical representation of cubic TiO2 nanoparticle formation during hydrolysis through sol-gel process.