[OPy][BF₄] Selective Extraction for Trace Hg²⁺ Detection by Electrochemistry: Enrichment, Release and Sensing

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Electrochemistry

Background:

• Accurate detection of trace mercury ions (Hg2+) is crucial for environmental monitoring and ensuring water safety.
• Existing methods for Hg2+ detection may face challenges with sensitivity and interference from other ions.
• Electrochemical sensing offers a promising avenue for sensitive and selective analyte detection.

Purpose of the Study:

• To develop and validate an electrochemical strategy for the sensitive and selective detection of trace mercury ions (Hg2+).
• To investigate the use of temperature-controlled N-octylpyridinium tetrafluoroborate ([OPy][BF4]) dispersive liquid-liquid microextraction for Hg2+ preconcentration.
• To enhance sensor performance, including sensitivity and anti-interference ability, through a novel Hg2+ releasing procedure.

Main Methods:

• Utilized N-octylpyridinium tetrafluoroborate ([OPy][BF4]) for selective dispersive liquid-liquid microextraction of Hg2+ from aqueous samples.
• Employed a temperature-controlled extraction process to optimize Hg2+ adsorption by [OPy][BF4].
• Developed a buffer solution (water and acetonitrile) to release Hg2+ from the [OPy][BF4] complex for electrochemical detection.

Main Results:

• The [OPy][BF4] demonstrated selective extraction of Hg2+ via adsorption by its unsaturated nitrogen atom.
• A novel procedure involving dilution with a water-acetonitrile buffer effectively released adsorbed Hg2+ for detection.
• Achieved a low detection limit of 0.0315 μg/L (S/N = 3) with a linear range of 0.1 to 1 μg/L.
• The sensor exhibited good recovery rates (106% to 118%) and improved anti-interference capabilities.

Conclusions:

• The proposed electrochemical method combined with [OPy][BF4] microextraction and a specific releasing procedure offers a highly sensitive and selective approach for trace Hg2+ determination.
• This method significantly enhances sensor performance, making it suitable for practical environmental monitoring and water safety applications.
• The developed technique holds great potential for accurate and reliable quantification of trace mercury ions in complex matrices.