A Paper-Based Colorimetric Sensor for Highly Sensitive and Selective Detection of Multi-metal Ions in Water

In this article, we present a NaYF4:Eu3+-based ultrasensitive colorimetric detection technique and demonstrate its successful implementation for the detection of four metal ions in water. The developed colorimetric sensors demonstrated exceptional stability in 100% aqueous solution and showed distinct absorption spectrum signals and significant color differences for Cu+2, Mn+2, Co+2, and Mo+4. Additionally, an attempt is made to detect heavy metal ions from mixtures of two or three metals. In that scenario, we also noticed distinct colors for distinct combinations. A simple test strip was developed for visual monitoring of four metal ions with a detection limit approximated by the naked eye. This suggested that colorimetric approach enables fast, sensitive, and portable detection of various metal ions, indicating a significant potential for on-site rapid water quality analysis.