Synthesis and characterization of novel tetra cyclo[4]pyrrole ether as an anion recognition element for nanocomposite nitrate ion selective carbon paste electrode

• Cyclo[4]pyrrole ether was synthesized and characterized by spectroscopy methods.
• C4PE was used as a recognition element in a nitrate ion selective electrode.
• C4PE displayed high selectivity to nitrate over various anions.
• C4PE sensor was applied to the determination of nitrate ion in water samples.

Novel tetra cyclo[4]pyrrole ether cation (C4PE) was synthesized and characterized by different spectroscopy methods. Cyclo[4]pyrrole ether was synthesized by oxidation reaction of pyrrole with Cu(II) nitrate in acetonitrile. Conductometric data in acetonitrile shows C4PE behaves as a divalent cation salt with two nitrate ions undergoing primary and secondary dissociations. C4PE was used as a recognition element in the form of a composite with carbon paste as a selective electrode for the potentiometry sensing of nitrate in water samples. The electrode has a linear response to nitrate with a detection limit of 1 × 10−5 mol L−1 and exhibit a Nernstian slope (57.5 ± 0.6 mV/decade) between pH 3.6 and 9.6 with a fast response time less than 10 s. The selectivity coefficient values indicate high selectivity for nitrate ions over various anions (NO3 > NO2− > Cl− > Br− > I− > F− > CH3COO− > SO42− > IO3− > ClO4−). The electrodes were used over a period of 60 days with good reproducibility. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of nitrate ions in mineral and drinking water samples.

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