Reusable and pH-Stable Luminescent Sensors for Highly Selective Detection of Phosphate.

Do Yeob Kim,Bongjin Jeong,Young Il Kim,Dong Gyu Kim,Hyung-Kun Lee,Jungseok Heo

doi:10.3390/polym14010190

Do Yeob Kim, Bongjin Jeong + Show 4 more

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https://doi.org/10.3390/polym14010190

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Abstract

Phosphate sensors have been actively studied owing to their importance in water environment monitoring because phosphate is one of the nutrients that result in algal blooms. As with other nutrients, seamless monitoring of phosphate is important for understanding and evaluating eutrophication. However, field-deployable phosphate sensors have not been well developed yet due to the chemical characteristics of phosphate. In this paper, we report on a luminescent coordination polymer particle (CPP) that can respond selectively and sensitively to a phosphate ion against other ions in an aquatic ecosystem. The CPPs with an average size of 88.1 ± 12.2 nm are embedded into membranes for reusable purpose. Due to the specific binding of phosphates to europium ions, the luminescence quenching behavior of CPPs embedded into membranes shows a linear relationship with phosphate concentrations (3–500 μM) and detection limit of 1.52 μM. Consistent luminescence signals were also observed during repeated measurements in the pH range of 3–10. Moreover, the practical application was confirmed by sensing phosphate in actual environmental samples such as tap water and lake water.

Highlights

Algal blooms are known to occur in lakes, rivers, and oceans, with complex behavior due to various prevailing factors such as nutrients (NO3 −, NH4 +, and PO4 3− ) along with water temperature, flow rate, rainfall, and dissolved oxygen [1]
To develop a phosphate sensor that can be deployed in the field and can be operated unattended, we present a photoluminescence phosphate sensor based on an coordination polymer particle (CPP) with high sensitivity, selectivity, and wide working range of pH
Eu-TCAs composed of Eu ions and TCA as a multidentate ligand containing three carboxylic groups were synthesized in the form of CPP under solvothermal and high-pressure conditions

Summary

Introduction

Algal blooms are known to occur in lakes, rivers, and oceans, with complex behavior due to various prevailing factors such as nutrients (NO3 − , NH4 + , and PO4 3− ) along with water temperature, flow rate, rainfall, and dissolved oxygen [1]. Extensive research has been conducted on the conservation of aquatic environments through seamless data monitoring of HABs, prediction of their occurrence, and intervention of appropriate algaeremoval treatments [4] To this end, water environments have been monitored using various sensors such as pH, chlorophyll a, phycocyanin, total nitrogen, NH4 -N, NO3 -N, total phosphorous (TP), and PO4 -P sensors. In the case of TP and PO4 -P, there is a general method for quantifying the reaction with a coloring agent after reacting with an oxidizing agent under the conditions of high temperature and high pressure This complicated analysis process limits the field deployment applications of phosphate sensors without the aid of chemical reagents and makes phosphate sensors only applicable in the laboratory. Phosphate ions prefer different forms according to the acidity of the dissolved aqueous solution This makes it difficult to realize phosphate sensors that can work in a wide pH range. The widely adapted size-exclusion principle for sensor selectivity is difficult to apply in phosphate sensors owing to its relatively large ion size

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