Nitrate sensing with molecular cage ionophores: a potentiometric approach

Abstract

Nitrate ions are widespread environmental pollutants in water and soil, posing critical risks to both human health and ecosystems. This study introduces a molecular cage as a novel ionophore for potentiometric nitrate-selective ion-selective electrodes (ISEs) designed for enhanced specificity and sensitivity. Among six synthetic candidates, the electrode incorporating a 1,3,5-tri(p-hydroxyphenyl)benzene-based chlorotriazine pillared cage molecule (CAGE-1) exhibited superior performance, characterized by a linear response in the nitrate concentration range of 1.0 × 10⁻⁵ to 1.0 × 10⁻¹ M, with a high coefficient of determination (R² = 0.9971) and a slope of −53.1 ± 1.4 mV dec⁻¹. The electrode also achieved a limit of detection of 7.5 × 10⁻⁶ M. These findings highlight the potential of molecular cages as ionophores for nitrate sensing in environmental applications.