Potentiometric sensors for phenylureas based on their molecularly imprinted particles

Abstract

A molecularly imprinted polymer (MIP), with special molecule recognition properties of different phenylurea
herbicides namely liuron (LU), isoproturon (IPU), diuron (DU), fenuron (FU) and methiuron (MU), was prepared
by thermal polymerization in which phenylureas acted as the template molecules, methacrylic acid (MAA)
acted as the functional monomer and ethylene glycol dimethacrylate (EGDMA) acted as the crosslinker. A
biomimetic potentiometric field monitoring device was developed for the assessment of these phenylurea
herbicides based on these newly synthesized imprinted polymers. The sensing elements were fabricated by
the inclusion of phenylurea imprinted polymers in polyvinyl chloride (PVC) matrix. The sensors showed a
high selectivity and a sensitive response to the template in an aqueous system. Electrochemical evaluation of
these sensors revealed near-Nernstian response with slopes of 66.1±0.5 (r
2
= 0.998), 59.6±1.3 (r
2
= 0.997),
62.3±0.6 (r
2
= 0.998), 67.1±0.3 (r
2
= 0.998) and 71.5.0±0.4 (r
2
= 0.998) mV decade− 1
with a detection limit of 1.0
× 10-5
, 7.1 × 10-6
, 1.3 × 10-5
, 1.8 × 10-5
and 1.6 × 10-5 mol L-1
with MIP/LU, MIP/IPU, MIP/DU, MIP/FU and MIP/MU
membrane based sensors plasticized with DOP, respectively. The sensors were easily used in a double
channel flow injection system and compared with a tubular detector. The method had the requisite accuracy,
sensitivity and precision to assay phenylureas in water samples.