Nanomaterial-Based Carbon Paste Electrodes for Voltammetric Determination of Naproxen in Presence of Its Degradation Products.

The present work describes a novel, simple, and fast electroanalytical methodology for naproxen (NAP) determination in pharmaceutical formulations and biological fluids in the presence of its degradation products. Carbon paste electrodes (CPEs) modified with different carbon nanomaterials, namely, glassy carbon powder (GCE), multiwall carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), graphene nanosheets (Gr), and graphene oxides (GO) were tested. Comprehensive studies were performed on the electrode matrix composition including the nature of the pasting liquids, pH, carbon nanomaterials, and mode of electrode modification.

Performance of a portable biosensor for the analysis of ethion residues.

Sensitive disposable potentiometric sensors for determination of the organophosphorus pesticide (OPs), ethion and its degradation residues have been constructed. The fabricated screen printed sensors are based on multi-walled carbon nanotube-polyvinyl chloride (MWNT-PVC) composite incorporated with α-cyclodextrin (α-CD) ionophore for butyrylcholine (BuCh) determination. Butyrylcholinesterase (BuChE) activity was measured through monitoring the BuCh hydrolysis using the fabricated sensors.

Miniaturized ionophore-based potentiometric sensors for the flow-injection determination of metformin in pharmaceutical formulations and biological fluids.

Miniaturized potentiometric sensors based on β-cyclodextrins (β-CDs) are described for determination of metformin (Mf) in pharmaceutical preparations and biological fluids. Electrode matrix compositions are optimized on the basis of the nature and content of sensing ionophore, ionic sites and plasticizers. Coated wire electrodes (CWEs) modified with heptakis(2,3,6-tri-O-methyl)-β-CD, sodium tetrakis(4-fluorophenyl)borate (NaTFPB) and 2-fluorophenyl 2-nitrophenyl ether (f-NPE), work satisfactorily in the concentration range from 10(-6) to 10(-1) mol L(-1) with Nernstian compliance (55.

Novel multi walled carbon nanotubes/β-cyclodextrin based carbon paste electrode for flow injection potentiometric determination of piroxicam.

A novel carbon paste electrode based on functionlized multi-walled carbon nanotubes/β-cyclodextrin composite (FMWCNTs/β-CD-CPE) is described for potentiometric determination of piroxicam (PXM). Improved sensitivity and selectivity was achieved by application of CDs as molecular host-guest recognition elements and MWCNTs. The electrochemical performance of carbon paste electrodes incroporated with FMWCNTs/β-CD composite was compared to those incroporated with MWCNTs and free CDs.

Novel PVC-membrane electrode for flow injection potentiometric determination of Biperiden in pharmaceutical preparations.

The construction and performance characteristics of Biperiden (BP) polyvinyl chloride (PVC) electrodes are described. Different methods for electrode fabrication are tested including; incorporation of BP-ion pairs (BP-IPs), incorporation of ion pairing agents, or soaking the plain electrode in BP-ion pairs suspension solution. Electrode matrices were optimized referring to the effect of modifier content and nature, plasticizer and the method of modification.

Catalytic spectrophotometric determination of iodide in pharmaceutical preparations and edible salt.

The catalytic effect of iodide on the oxidation of four dyes: viz. variamine blue (VB), methylene blue (MB), rhodamine B (RB), and malachite green (MG) with different oxidizing agents was investigated for the kinetic spectrophotometric determination of iodide. The above catalyzed reactions were monitored spectrophotometrically by following the change in dye absorbances at 544, 558, 660, or 617 nm for the VB, RB, MB, or MG catalyzed reactions, respectively.

Kinetic catalytic determination of trace levels of iodide based on the oxidation of basic dyes with hydrogen peroxide monitored potentiometrically using simple PVC electrodes.

Four sensitive catalytic potentiometric methods have been developed for trace levels determination of iodide based on its catalytic effects on the oxidation of four dyes: viz. variamine blue (VB), rhodamine B (RB), methylene blue (MB) and malachite green (MG), with H(2)O(2) in H(3)PO(4) medium at 25±0.5°C.

Disposable potentiometric sensors for monitoring cholinesterase activity.

A highly sensitive disposable screen-printed butyrylcholine (BuCh) potentiometric sensor, based on heptakis (2,3,6-tri-o-methyl)-β-cyclodextrin (β-CD) as ionophore, was developed for butyrylcholinesterase (BuChE) activity monitoring. The proposed sensors have been characterized and optimized according to the constituents of homemade printing carbon ink including β-CD, anionic sites, and plasticizer. The fabricated sensor showed Nernstian responses from 10(-6) to 10(-2)mol L(-1) with detection limit of 8 × 10(-7)mol L(-1), fast response time (1.

Towards disposable sensors for drug quality control: Dextromethorphan screen- printed electrodes.

A simple, rapid, reliable, and reproducible method for mass production of disposable sensors using screen-printing technology is described. Homemade printing has been characterized and optimized on the basis of effects of the modifier and plasticizers. The fabricated bi-electrode potentiometric strip containing both working and reference electrode was used as dextromethorphan (DXM) sensor.

Potentiometric determination of cetylpyridinium chloride using a new type of screen-printed ion selective electrodes.

A new type of screen-printed ion-selective electrode for the determination of cetylpyridinium chloride (CPC) is presented. These new electrodes involve in situ, modified and unmodified screen-printed ion-selective electrodes for the determination of CPC. The screen-printed electrodes (SPEs) show a stable, near-Nernstian response for 1 x 10(-2) to 1 x 10(-6) M CPC at 25 degrees C over the pH range 2-8 with cationic slope 60.

Carbon paste and PVC electrodes for the flow injection potentiometric determination of dextromethorphan.

The construction and performance characteristics of dextromethorphan (DXM) carbon paste (CPEs) and polyvinyl chloride (PVC) electrodes are described. Different modes for electrode modification, including incorporation of ion pairs (IPs), ion pairing agent or soaking the plain electrode in IPs suspension, have been used. Matrices compositions were optimized referring to the effect of modifier and plasticizer.

Spectrophotometric determination of terfenadine in pharmaceutical preparations by charge-transfer reactions.

A simple, rapid and accurate method for the spectrophotometric determination of terfenadine has been developed. The proposed method based on the charge-transfer reactions of terfenadine, as n-electron donor, with 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, p-CLA) as pi-acceptors to give highly colored complexes. The experimental conditions such as reagent concentration, reaction solvent and time have been carefully optimized to achieve the highest sensitivity.