Nitrate sensing with molecular cage ionophores: a potentiometric approach

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 x 10-5 to 1.0 x 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 x 10-6 M. These findings highlight the potential of molecular cages as ionophores for nitrate sensing in environmental applications.