Selective and sensitive electrochemical detection of methyl parathion using chemically modified overhead projector sheets as flexible electrodes

A new, flexible and chemically modified disposable strip is demonstrated to be an efficient electrochemical sensor for the detection of environmentally hazardous pesticide, namely methyl parathion (MP). These disposable strips are prepared by surface modification of nonconductive polyester of polyvinyl alcohol sheets used as overhead projector (OHP) films with 3-mercaptopropyltrimethoxysilane (MPTMS) layers followed by electroless deposition of silver (Ag/MPTMS/OHP), essentially to bring in the conductivity and catalytic activity towards MP detection. Further deposition of zinc oxide (ZnO) onto Ag/MPTMS/OHP strips results in enhanced reduction current towards MP sensing. This is attributed to the ability of ZnO to promote electron transfer reaction and its large surface area arising out of the resultant nanostructured material during deposition leading to effective adsorption of MP molecules on such chemically modified strips. Structural and morphological characterizations of these strips are carried out by using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) studies. Electroanalytical results show that these strips are selective and sensitive to MP detection over a wide linear concentration ranging from 2.5 nM to 75 mu M along with a sensitivity value of 2.7632 mu A/mu M. A very low detection limit of 0.07 nM is determined for the proposed sensor. Moreover, this non-enzymatic electrochemical sensor is applied further to determine MP in real samples analysis and the results obtained are promising. (C) 2015 Elsevier B.V. All rights reserved.