Abstract
All-solid-state potentiometric sensors were prepared by using polyaniline (PANI) as the solid contact material. A film of PANI (thickness approximately being 0.25 µm) was deposited on a solid substrate (carbon screen printed platform). The PANI layer was subsequently coated with an ion-selective membrane (ISM) containing uniform-sized molecularly imprinted nanoparticles to produce a solid-contact ion-selective electrode (SC/ISE) for bispyribac herbicide (sensor I). In addition, aliquat 336 was also used as an ion exchanger in plasticized PVC membrane (sensor II). The proposed sensors revealed a remarkably improved sensitivity towards bispyribac ions with anionic slopes of −47.8 ± 1.1 (r2 = 0.9995) and −44.4 ± 1.4 (r2 = 0.9997) mV/decade over a linear range 1.0 × 10−2–8.6 × 10−6 M, 1.0 × 10−2–9.0 × 10−6 M and detection limits of 1.33 and 1.81 µg/mL for sensors I and II, respectively.Selectivity of both sensors is significantly high for different common pesticides and inorganic anions. The potential stability of the SC/ISEs was studied using chronopotentiometry. Electrochemical impedance spectrometry was used to understand the charge-transfer mechanisms of the different types of ion-selective electrodes studied. The impedance response of the electrodes was modelled by using equivalent electrical circuits. The sensors were used for a direct measurement of the bispyribac content in commercial herbicide formulations and soil samples collected from agricultural lands planted with rice and sprayed with bispyribac herbicide. The results agree fairly well with data obtained using HPLC method.
Highlights
Herbicides are commonly used in agriculture to control the growth of unwanted weeds
We present for the first time a novel screen-printed potentiometric sensor integrated with molecularly imprinted polymer (MIP) for detecting bispyribac herbicide
For washed/MIP, a O–H peak appeared at 3547 cm−1 which is very close to the O–H peak appeared in Non-imprinted polymer (NIP) beads (3543 cm−1 )
Summary
Herbicides are commonly used in agriculture to control the growth of unwanted weeds. They act as plant-hormone mimics which can control the cell division, bud generation, root initiation, etc. [1].To get rid of rice weed, bispyribac-sodium (BS) is the most commonly recommended herbicide with a Molecules 2019, 24, 712; doi:10.3390/molecules24040712 www.mdpi.com/journal/moleculesMolecules 2019, 24, 712 broad spectrum and large effect. Herbicides are commonly used in agriculture to control the growth of unwanted weeds. They act as plant-hormone mimics which can control the cell division, bud generation, root initiation, etc. To get rid of rice weed, bispyribac-sodium (BS) is the most commonly recommended herbicide with a Molecules 2019, 24, 712; doi:10.3390/molecules24040712 www.mdpi.com/journal/molecules. Molecules 2019, 24, 712 broad spectrum and large effect. It has an inhibition effect on the activity of acetolactate synthetase enzyme that affects on plant growth. Bispyribac has been used for controlling a broad range of weeds [2,3]. In Egyptian and American legislations, they established maximum limits for pesticides in drinking and environmental water, but bispyribac-sodium is not included
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