Analytical Sciences

Strategic Approaches for Highly Selective and Sensitive Detection of Hg²⁺ Ion Using Mass Sensitive Sensors

Hyeoun Ji PARK and Soo Suk LEE

Department of Pharmaceutical Engineering, Soonchunhyang University, 22 Soonchunhyangro, Shinchang-myeon, Asan-si, Chungcheongnam-do 31538, Republic of Korea

Here we present a quartz crystal microbalance (QCM) sensor for the highly selective and sensitive detection of Hg²⁺ ion, a toxic chemical species and a hazardous environmental contaminant. Hg²⁺ ion can be quantitatively measured based on changes in the resonance frequency of QCM following mass changes on the QCM sensor surface. The high selectivity for Hg²⁺ ion in this study can be obtained using a thymine–Hg²⁺–thymine pair, which is more stable than the adenine-thymine base pair in DNA. On the other hand, gold nanoparticles (AuNPs) and their size-enhancement techniques were used to amplify the QCM signals to increase the sensitivity for Hg²⁺ ion. With this strategic approach, the proposed QCM sensor can be used to quantitatively analyze Hg²⁺ ion with high selectivity and sensitivity. The detection limit was as low as 98.7 pM. The sensor failed to work with other metal ions at concentrations 1000-times higher than that of the Hg²⁺ ion. Finally, the recovery does not exceed 10% of the original value for the detection of Hg²⁺ ion in tap and bottled water. The results indicate acceptable accuracy and precision for practical applications.

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