A simple fluorometric method using chlorophyll a for determination of Hg²⁺ ion

A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg²⁺ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg²⁺ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly on exposure to various concentrations of Hg²⁺ ion. This forms the basis for the determination of Hg²⁺ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0-10 μM with r ² = 0.997 and the limit of detection for Hg ²⁺ ion was 1.3 μM. Ions including Pb²⁺, Cd ²⁺, Ag⁺, Zn²⁺, Co²⁺, Ni ²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Ru ³⁺, Er³⁺, K⁺, Na⁺, NH₄ ⁺, Cl^-, NO₃ ^-, CH ₃COO^- and SO₄ ^2- did not interfere with the measurement of Hg²⁺ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can provide an alternative, sensitive and economical way to determine Hg²⁺ ion.