Abstract
Trace mercury ion (Hg) detection is important for environmental monitoring and water safety. In this work, we study the electrochemical strategy to detect trace Hg based on the preconcentration of temperature-controlled N-octylpyridinium tetrafluoroborate ([OPy][BF]) dispersive liquid–liquid microextraction. The [OPy][BF] selectively extracted Hg from aqueous solution by the adsorption of unsaturated N in [OPy][BF], which increased the concentration of Hg and decreased that of other interference ions. It was noted that the adsorption of [OPy][BF] to Hg was weakened by aqueous solution. Hence, after extraction, precipitated [OPy][BF] was diluted by a buffer solution comprising a mixture of water and acetonitrile to release Hg and the single was detected by electrochemistry. Water is proposed to release Hg adsorbed by [OPy][BF], 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 releasing procedure. The detection limit (S/N = 3) of the sensor is 0.0315 g/L with a linear range from 0.1 to 1 g/L. And the sensor exhibits good recovery with an range from 106 % to 118%, which has great potential for trace Hg determination.
Highlights
Published: 27 November 2021Mercury exhibits high biotoxicity and is a major threat to ecosystems and human health [1] owing to its extremely high bioaccumulation factor in the food chain [2]
The higher enrichment factor represents higher concentration of the mercury in the final Ionic liquids (ILs) phase, which is beneficial for detection of trace concentrations
The enrichment factor is defined as the ratio of the initial mercury concentration in water to the ultimate mercury concentration in the IL phase, which is depicted as in Formula (1), where Cult refers to the extracted mercury concentration in the IL phase, and Cin refers to the concentration of mercury in the initial aqueous solution
Summary
Published: 27 November 2021Mercury exhibits high biotoxicity and is a major threat to ecosystems and human health [1] owing to its extremely high bioaccumulation factor in the food chain [2]. Considering the toxicological effects and wide applications of mercury, it is necessary to detect trace Hg2+ in water for ensuring safety. Atomic fluorescence spectrometry (AFS) [3], cold vapor atomic absorption spectrometry (CV-AAS) [4] and inductively coupled plasma mass spectrometry (ICP-MS) [5,6] are authoritative and popular methods for trace mercury detection. These methods require large, expensive instrumentation and complex operations. Electrochemistry [16,17,18,19] has advantages such as economy, portability and labelfree methodology, which is promising for trace mercury detection Several simple and novel strategies have been studied and reported for Hg2+ detection, such as colorimetry [7,8], fluorimetry [9,10,11], Raman spectrometry [12,13,14] and localized surface plasmon resonance [15], but most of these methods have low sensitivity, specific labeling and high-cost-instrument requirements.
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