Rational design of in situ monolithic imprinted polymer membranes for the potentiometric sensing of diethyl chlorophosphate - a chemical warfare agent simulant

Abstract

Molecularly imprinted polymer membrane was prepared by semicovalent imprinting strategy wherein i) the template diethyl chlorophosphate (DCP). (a simulant of organophosphorous nerve agents), is covalently linked to the reactive step followed by noncovalent rebinding and ii) in situ functional monomer vinyl aniline (VA) during imprinting polymerization via single pot synthesis in presence of additional functional monomer. 2-hydroxyethyl methacrylate (HEMA) and crosslinking monomer, ethylene glycol dimethacrylate (EGDMA) after addition of 2-nitrophenyl octyl ether (NPOE) and 2,2'-azobisisobutyrnitrile (AIBN) as plasticizer and initiator respectively. The resulting membrane is integrated with a potentiometric transducer while designing a DCP sensor. The fabricated sensor 10(-6) - 10(-2) M with a lower detection limit of 10(-6) M (0.17 ppm). In responds over a wider concentration range of 10(-6) addition. in situ monolithic membrane based sensor was designed by adopting noncovalent imprinting strategy also. A detailed comparison is made between semicovalent and noncovalent in situ membrane based sensors on the prime sensor performance criteria such as sensitivity, selectivity, working range, response time. reusability and reversibility Again the relative merits and demerits of semicovalent vis-a-vis noncovalent strategy based in situ monolithic membrane sensors were also highlighted. The probable molecular recognition mechanism is also discussed