[OPy][BF(4)] Selective Extraction for Trace Hg(2+) Detection by Electrochemistry: Enrichment, Release and Sensing

Trace mercury ion (Hg [Formula: see text]) detection is important for environmental monitoring and water safety. In this work, we study the electrochemical strategy to detect trace Hg [Formula: see text] based on the preconcentration of temperature-controlled N-octylpyridinium tetrafluoroborate ([OPy][BF [Formula: see text]]) dispersive liquid–liquid microextraction. The [OPy][BF [Formula: see text]] selectively extracted Hg [Formula: see text] from aqueous solution by the adsorption of unsaturated N in [OPy][BF [Formula: see text]], which increased the concentration of Hg [Formula: see text] and decreased that of other interference ions. It was noted that the adsorption of [OPy][BF [Formula: see text]] to Hg [Formula: see text] was weakened by aqueous solution. Hence, after extraction, precipitated [OPy][BF [Formula: see text]] was diluted by a buffer solution comprising a mixture of water and acetonitrile to release Hg [Formula: see text] and the single was detected by electrochemistry. Water is proposed to release Hg [Formula: see text] adsorbed by [OPy][BF [Formula: see text]], and the acetonitrile serves as a co-solvent in buffer solution. Sensitivity and anti-inference ability of sensors were improved using the proposed method and Hg [Formula: see text] releasing procedure. The detection limit (S/N = 3) of the sensor is 0.0315 [Formula: see text] g/L with a linear range from 0.1 to 1 [Formula: see text] g/L. And the sensor exhibits good recovery with an range from 106 % to 118%, which has great potential for trace Hg [Formula: see text] determination.