Potentially toxic elements in groundwater of the upper Brahmaputra floodplains of Assam, India: water quality and health risk.

This paper presents the groundwater quality assessment of the upper Brahmaputra floodplains of Assam on a seasonal basis. A total of 88 samples were analyzed for the presence of potentially toxic elements in two seasons. In addition, an attempt is made to identify any possible associated health risks to the residents via the drinking water pathway. The study reveals the presence of various potentially toxic elements, in particular, manganese, iron, nickel, and fluoride concentration exceeding the drinking water specifications set by BIS and WHO drinking water standards. The degree of groundwater contamination was assessed using the Water Quality Index, Heavy metal Pollution Index, Heavy metal Evaluation Index, and Degree of Contamination. The spatial distribution maps of groundwater quality were prepared using geographical information system. The non-carcinogenic health risk was evaluated using hazard quotients and hazard index as per the United States Environmental Protection Agency methodology. The hazard quotient of fluoride and manganese have values > 1, which exceeds USEPA recommended benchmark. The health risk assessment identified that the risk was highest during the pre-monsoon season, and the child population is more vulnerable to non-carcinogenic risk than the adults. Findings of cancer risk identified that pre-monsoon groundwater samples from the Golaghat District pose the highest health risks in the upper Brahmaputra floodplains. The risk is highest in the southwest of the study area, followed by the south and then by the north.

Detection of anticancer drug tamoxifen using biosensor based on polyaniline probe modified with horseradish peroxidase.

Amperometric biosensor based on horseradish peroxidase immobilized via glutaraldehyde on the polyaniline modified platinum electrode shows evidenced promising characteristics in detecting anticancer drug tamoxifen. The sensor was fabricated simply by adsorbing horseradish peroxidase enzyme on the electrode surface for which Cyclic Voltammetry was used to monitor the electro-catalytic reduction of tamoxifen under diffusion-adsorption controlled conditions. Fourier Transform Infrared Spectroscopy, Cyclic Voltammetry and Electrochemical Impedance Spectroscopic techniques are used to characterize the electrochemical interfacial properties of surface modified electrodes. The first-hand effort on modified biosensor within Platinum/Polyaniline/Horseradish peroxidase biosensor system has demonstrated excellent electro-analytical properties with biosensor sensitivity of 1.6 µA ng mL(-1). The optimum limit of detection and limit of quantification are 0.07 ng mL(-1) and 0.29 ng mL(-1) respectively for the determination of anticancer drug tamoxifen. It is felt that the present study will help in improving our knowledge of cost-effective quantitative determination of tamoxifen in metabolized biological fluids and other pharmaceutical formulations.

Voltammetric quantification of tamoxifen.

The electrochemical behaviour of tamoxifen has been investigated at gold electrode by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and squarewave voltammetric techniques. The dependence of current and potential on pH, concentration, scan rate, nature of solvent, surfactants and different surfactant concentration is investigated. Tamoxifen is oxidized in a single two-electron, irreversible and diffusion-controlled wave. Linear calibration plots are obtained over the concentration range 1.0-5.0 and 1.0-6.0 µgmL(-1) in 1.0 M KCl and Britton Robinson buffers (pH 2.51) respectively. The procedure has been applied to the assay of the drug in tablet form with mean percentage recoveries of 99.98%. The suggested method can be successfully applied to the determination of tamoxifen in different drug formulations.