Surface functionalization of smectite-type clay by facile polymerization of β-cyclodextrin using citric acid cross linker: Application as sensing material for the electrochemical determination of paraquat

A composite material obtained by polymerization of β-cyclodextrin using citric acid cross linker on the surface of smectite was used to elaborate an electrochemical sensor for the determination of paraquat (PQ2+). The hybrid material was characterized by X-ray diffraction, FTIR and thermal analysis. The presence of β-CD on the starting clay was confirmed by investigating the ion exchange properties of the organoclay by multisweep cyclic voltammetry. A sensor based on a glassy carbon electrode (GCE) coated by the organosmectite for PQ2+ sensing was proposed. The electroanalytical procedure implied two steps: the open circuit preconcentration of PQ2+ and the detection of accumulated PQ2+ in 0.1 M NaCl. The peak current on the organoclay modified GCE was >11-fold higher than that exhibited by GCE covered by a film of the pristine clay. Many parameters that can affect the stripping response were optimized, that led to a linear calibration curve for PQ2+ in the concentration ranging from 25.7 to 514.3 μg/L, with a detection limit of 0.74 μg/L (S/N = 3). The interfering effect of some compounds and ions was examined on the stripping response of PQ2+. The proposed sensor was successfully applied in the determination of PQ2+ in water samples.