N. Y. Sreedhar

Differential pulse polarographic determination of dicrotophos, crotoxyphos and chlorfenvinphos in grains and soils

A simple, sensitive and rapid differential pulse polarographic method has been developed for the quantitative determination of organophosphorus pesticides such as dicrotophos, crotoxyphos and chlorfenvinphos in agricultural formulations in universal buffers of a pH range 2.0-12.0. The sample is treated with ethanol to facilitate the dissolution of these pesticides. Both standard addition and calibration methods can be used for the analyses. The lower detection limits are 1.25x10(-9), 1.05x10(-9) and 1.0x10(-9) M, respectively. The method can be applied successfully to determination of these pesticides in grains and soil.

An electrochemical approach to the determination of dinobuton: a study of water samples

The electrochemical reduction behaviour of dinobuton was studied by employing advanced electrochemical techniques such as dc polarography, cyclic voltammetry, differential pulse polarography (DPP), controlled potential electrolysis and millicoulometry in universal buffers of pH ranging from 2.0 to 12.0. Polarographic and cyclic voltammetric studies of dinobuton showed that it is reduced in two six-electron steps in acidic medium and in two four-electron steps in basic medium. Polarographic waves are irreversible and diffusion controlled in nature and are precisely proportional to the concentration of dinobuton. A reduction mechanism is proposed on the basis of voltammetric results and reduction product analysis. The dependence of the DPP peak on various parameters was studied and the optimum conditions for the determination of dinobuton were found. Finally, the developed DPP method was applied to the determination of dinobuton in agricultural formulations and in spiked water samples. Evaluation by the standard addition method confirmed the accuracy of the analytical procedure.

Electrochemical Reduction Behaviour of Zileuton at a Dropping Mercury Electrode by Polarography

Electrochemical behaviour of anticancer drug zileuton was investigated by direct current polarography (DCP) and differential pulse polarography using a dropping mercury electrode (DME) as working electrode and Ag/AgCl reference electrode in universal buffer of pH range from 2.0 to 12.0. The drug was extracted from the dosage forms in dimethyl formamide (DMF). Kinetic parameters such as diffusion co-efficient (D) and heterogeneous forward rate constants (k0f,h) are evaluated and reported. The differential pulse polarographic method has been developed for the determination of this drug in pharmaceutical formulations.

The simultaneous determination of omethoate and dichlorvos pesticides in grain samples using a palladium and graphene composite modified glassy carbon electrode

An electrochemical sensor based on a palladium (Pd) and graphene (Gr) composite modified glassy carbon electrode (GCE) was fabricated, characterised and used for the simultaneous determination of omethoate (OMT) and dichlorvos (DCV) in grain samples. The Pd/Gr/GCE was characterized by scanning electron microscopy (SEM) and cyclic voltammograms (CV). The modified electrode displayed a greatly improved voltammetric response to OMT and DCV. Square wave voltammetry (SWV) was used for the individual and simultaneous determination of OMT and DCV. Various conditions were optimized, such as the pH of the buffer, the applied sample volume, the accumulation potential, the accumulation time, the square wave frequency and the step potential. Well defined reduction (OMT at CO, DCV at CC) peaks were obtained over the potential maximum in an acidic medium in phosphate buffer solution at −0.50 V and −0.80 V for both OMT and DCV. Low current peaks were obtained over the concentration of 3.50 × 10−8 M with detection limits 2.47 × 10−10 M and 3.28 × 10−10 M for OMT and DCV respectively. The composite modified electrode showed good stability and reproducibility. Therefore, the proposed method was successfully applied as an economical and simple sensor with a shorter analysis time.