To address the growing demand for decentralized, real-time water monitoring of hazardous water pollutants, this study presents a portable, multiplexed solid-state ion-selective membrane (ISM) sensor array capable of simultaneously detecting nitrate (NO₃⁻), ammonium (NH₄⁺), and chloride (Cl⁻) in water samples. This portable system integrates temperature compensation for reliable field analysis and an IoT framework for remote data transmission, enabling real-time monitoring and informed decision-m