Abstract:
A biomimetic potentiometric field monitoring device was developed for the trace determination of phorate (O,O-diethyl S-ethyl thiomethyl phophorodithioate) in natural waters. The sensing element was fabricated by the inclusion of phorate imprinted polymer materials in the polyvinyl chloride (PVC) matrix. The sensor surface can be reused without conditioning unlike most other conventional sensors. Operational parameters such as amount and nature of plasticizers sensing material, pH and response time were optimized. The response characteristics of the non-imprinted (NIPIM) and imprinted polymer inclusion membrane (IPIM) sensors for phorate were compared under optimum conditions. The IPIM sensor responds linearly to phorate in the concentration in the ranges 1. x 10(-9) to 1 x 10(-6) M and 1 x 10(-6) to 1 x 10(-5) M of different slopes with a detection limit of 1 x 10(-9) M. The selectivity was tested with various common organophosphorous (OP) pesticides and herbicides. In addition to superior sensitivity and selectivity of IPIM over NIPIM-based sensor, IPIM-based phorate sensor was found to be stable for 3 months and can be used for more than 40 times without any loss in sensitivity. The applicability for analyzing ground, river and tap-water samples was successfully demonstrated via recovery studies.
