A Simple and Effective Visual Fluorescent Sensing Paper-Based Chip for the Ultrasensitive Detection of Mercury Ions in Environmental Water

Overview

This paper from Yantai University and the Chinese Academy of Sciences describes a paper-based visual fluorescent sensing chip for ultrasensitive mercury ion (Hg2+) detection in environmental water. CdTe quantum dots are modified onto silica nanospheres and firmly anchored in the fiber interspaces of paper, avoiding unevenness from liquid evaporation. Mercury ions selectively and efficiently quench the fluorescence emitted at 525 nm, and results can be captured by smartphone camera. The method achieves a detection limit of 2.83 µg/L with a response time of 90 seconds. Real-sample spiking recovery tests in seawater (three regions), lake water, river water, and tap water yielded recoveries of 96.8 to 105.4%.

Note: the triage manifest listed metals as arsenic (As)/lead (Pb), which is incorrect; the paper addresses Hg2+ only.

Key numbers

• LOD: 2.83 µg/L Hg2+
• Response time: 90 seconds
• Fluorescence emission: 525 nm
• Recovery in spiked water samples: 96.8 to 105.4%
• Water matrices tested: seawater (3 sites), lake water, river water, tap water

Methods (brief)

CdTe quantum dots on silica nanospheres anchored to paper fiber interspaces. Hg2+ quenches quantum dot fluorescence via selective interaction. Smartphone camera captures grayscale data from paper chip under UV light. Selectivity over interfering ions (K+, Ca2+, Na2+, Mg2+, Al3+, Zn2+, Fe3+, Ag+, Co2+, Cu2+, Ni2+, Ba2+, Cr3+) evaluated.

Implications

Certification: Not applicable; water detection method, no food matrix data. Courses: Illustrates low-cost, portable, consumer-accessible mercury detection using paper-based chips and smartphones. App: Not applicable.

Related evidence

• testing/mercury-detection-methods

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