Trace mercury (II) detection and separation in serum and water samples using a reusable bifunctional fluorescent sensor

In this work, a reusable bifunctional fluorescent sensor for simultaneous detection and separation of trace Hg²⁺ in water and serum, which contains a naphthalimide derivative of 2,6-bis(aminomethyl)pyridine covalently grafted to the surface of silica particles, was developed. Meanwhile, the fluorescence characteristics and the adsorbent properties of the sensor were investigated in detail. This sensor showed a very good linearity (correlation coefficient of R² = 0.9991) in the range 0.1-1 μM of Hg²⁺ with detection limits lower than 6.8 × 10^-9 M. It can also be used as an adsorbent for the removal of mercuric ions from the contaminated aqueous solution. The regeneration of this sensor is very simple, only by modulating the pH value of the aqueous solution. It can be reused at least four cycles. In addition, the present approach has the advantages of rapidity, simplicity, and low cost. We believe that this approach may serve as a foundation for the preparation of practical fluorescent sensor for the rapid detection of Hg²⁺ in aqueous biological and environmental samples.