Water Nitrate Remote Monitoring System with Self-Diagnostic Function for Ion-Selective Electrodes

Abstract

The detection of nitrate pollutants is a widely used strategy for protecting water sources. Although ion-selective electrodes (ISEs) have been considered for the determination of ion concentrations in water, the accuracy of ISE technology decreases owing to the signal drift and decreasing sensitivity over time. The objectives of the present study were: (1) to develop an online water monitoring system mainly consisting of an Arduino board-based Internet-of-Things (IoT) device and nitrate ISEs; and (2) to propose a self-diagnostic function for monitoring and reporting the condition of the ISEs. The developed system communicates with the cloud server by using the message queuing telemetry transport (MQTT) protocol and provides monitoring information through the developed cloud-based webpage. In addition, the online monitoring system provides information on the electrode status, which is determined based on a self-diagnostic index (SDI, with a range of 0–100) of the electrode drift and sensitivity. The diagnostic method for monitoring and reporting the electrode status was validated in a one-month-long laboratory test followed by a field test in a stream near an agricultural facility. Moreover, a self-diagnostic index (SDI) was applied in the final field experiments with an accuracy of 0.77.

All-Solid-State Potentiometric Sensor Based on Graphene Oxide as Ion-to-Electron Transducer for Nitrate Detection in Water Samples

“…Even when the concentration of the interfering ions decreased to 10 −4 M, these last two anions showed substantial interference (Figure S4 and Table 2). Nevertheless, the selectivity coefficients were similar to the ones reported for a similar ISM composition, either in electrodes with an inner liquid configuration [52,53] or with different solid-contact transducers [37,54]. This indicates that the selectivity of the studied sensors is a function of the ISM composition rather than the nature of the inner transducing element.…”

A submersible probe with in-line calibration and a symmetrical reference element for continuous direct nitrate concentration measurements

“…Another approach for direct concentration measurements for anions has been developed based on a pulstrode protocol. 27 Submersible potentiometric probes 28,29 are by nature designed to perform measurements directly in the eld and have been used previously in environmental studies, 17,18,[30][31][32] but they require a pump to drive the sample towards the measuring site. To enable constant monitoring, the pump must run continually, which would lead to unreasonable power consumption and difficulties in deployment because of power source availability.…”