Novel electrospray ionization-tandem mass spectrometry strategy for monitoring mercury(ii) ion based on the competing system of mercury specific DNA and glutathione to mercury(ii) ion
Abstract
An electrospray ionization-tandem mass spectrometry (ESI-MS/MS) strategy was developed for the detection of mercury ion with high sensitivity and selectivity based on a competition system of glutathione and mercury specific DNA to mercury ion. Mercury ion selectively bound to a special mismatched DNA and glutathione (GSH) because thiol-containing tripeptide can effectively sequester Hg2+ ion from thymine–Hg2+–thymine structure. Following the competition reaction, the concentration of mercury ion in the analyte was indirectly reflected by monitoring the concentration change of free GSH by ESI-MS/MS method. The electrospray ionization-mass spectrometry (ESI-MS) analysis of the competition system provided the connection of mercury ion and mercury specific DNA (MSD), and also provided the process by which GSH competed mercury ion from MSD. Note that the proposed competing platform exhibits exquisite selectivity and sensitivity to Hg2+ ion with a detection limit of 5 nM. Furthermore, this assay design avoids the labeling of the probe, use of the quantum dot, fluorescence dye, and heavy metals. Therefore, it is much friendlier for the operators and the environment. The proposed method was applied to some real samples (tap water, lake water, and fish), and the obtained results were satisfactory.