Electrochemical detection and quantification of Reactive Red 195 dyes on graphene modified glassy carbon electrode.

Reactive Red 195 was detected from industrial waste samples electrochemically on graphene modified glassy carbon electrode (GCE), using both bare and surface changed GCE at different pH media from 1.0 to 13.0. The optimum pH was determined to be 4.0. RR 195 exhibited good linear responds at pH 4.0 on both electrode surfaces. Other parameters, such as accumulation potential, accumulation time, initial scan potential, pulse height, pulse width, and potential scan increment and scan rate are optimized and calibration plot was also derived on different concentrations of the dye. The stripping voltammetric behavior of dye exhibits very low limit of detection on graphene coated electrode (30 ppb). The adsorption of compound on GCE and graphene coated GCE are confirmed using atomic force microscopy studies.

Determination of pesticides using heteropolyacid montmorillonite clay-modified electrode with surfactant.

Redox behavior of three pesticides, namely isoproturon, carbendazim and methyl parathion was investigated electrochemically using heteropolyacid montmorillonite clay-modified glassy carbon electrode in the presence and absence of a surfactant, cetyl trimethyl ammonium bromide. A solution of 0.1M H(2)SO(4) in 50% aqueous alcohol (pH 1.0) was found to be suitable medium for electroanalysis. Isoproturon exhibited one well-defined oxidation peak around 1.2 V along with one more oxidation and reduction peaks. Carbendazim showed only one well-defined anodic peak around 1.4 V. Methyl parathion exhibited one well-defined reduction peak around -0.26 V and the oxidation peak appeared around 0.510 V. In the second cycle, a new cathodic peak was found around 0.420 V. The presence of surfactant enhanced the peak current and hence stripping voltammetric determination procedures for all the three pesticides were developed. Square wave stripping mode was employed and the maximum current experimental conditions were arrived at. Calibration plot was made for all the three pesticides. The determination limit and standard deviations were arrived at. The applicability of the method was also verified in a soil sample and water analyte.

Investigation on the usage of clay modified electrode for the electrochemical determination of some pollutants.

Redox behavior of three pollutants, namely endosulfan (EN), o-chlorophenol (OCP) and direct orange 8 (DO8) were investigated electrochemically using sodium montmorillonite clay modified glassy carbon electrode. Influence of pH, scan rate and concentration were studied on the voltammetric response. Suitable medium for the electrochemical studies of EN was pH 1.0 and for other two pollutants pH 13.0. EN exhibited one well-defined reduction peak accounting for irreversible 2e(-) transfer and leading to the removal of one chlorine atom. OCP underwent one electron oxidation to the formation of phenoxy radical resulting in an oxidation peak. DO8 showed two peaks for reductions and two peaks for oxidation as a result of the reduction of azo group and oxidation of phenoxide group. These electrochemical reactions of the three pollutants reveals the suitability of clay modified electrode for the electroanalysis. A differential pulse stripping voltammetric procedure for the determination of these pollutants was developed. The limits of determination for EN, OCP and DO8 are 5-300, 10-800 and 50-800 ppb, respectively.