Magnetic ionic liquid effervescence assisted liquid-liquid microextraction and atomic fluorescence spectrometry for sensitive determination of mercury species in water and wine samples

Abstract

A rapid method using a magnetic ionic liquid (MIL) in the effervescence-assisted liquid-liquid microextraction (EA-LLME) was developed for the separation and determination of inorganic and organic species of Hg in beverage samples. A chlorocomplex was formed with Hg(II) for its extraction in 75 µL of the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate ([P_6,6,6,14]FeCl₄). CO₂ bubbles disperse the MIL phase, followed by phase separation with a magnetic rod and the MIL dilution with chloroform. A rapid back-extraction was performed by an ultrasonic bath with 6 mol L⁻¹ HCl solution. The inorganic Hg(II) species was determined by cold vapour atomic fluorescence spectrometry (CV-AFS), while total Hg quantification involved a photooxidation step prior to preconcentration. Thus, organic species was calculated by the difference between the concentrations of total Hg and Hg(II). The extraction conditions were optimized achieving a maximum extraction efficiency of 98 % for Hg(II). The analytical performance included a relative standard deviation of 1.6 %, a limit of detection (LOD) and limit of quantification (LOQ) of 0.096 µg L⁻¹ and 0.113 µg L⁻¹ for Hg(II), respectively. The linear calibration range was 0.113–4 µg L⁻¹. The results showed that the proposed methodology was efficient and selective for Hg speciation analysis in water and wine samples.