1-Butyl-3-methylimidazolium hexafluorophosphate ionic liquid-based liquid–liquid microextraction for the determination of 4-nonylphenol and 4-tert-octylphenol in environmental waters

Abstract

In the present study, room-temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate was used as extraction solvent in a liquid–liquid microextraction (LLME) procedure followed by liquid chromatography for determining 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) in environmental water samples. RTIL-based LLME was a simple, inexpensive, and fast sample preparation method, and its parameters such as extraction time, addition of salt, selection of phase ratio, and pH value were optimized. The optimized method had acceptable limits of detection (LOD) and a precision of 2 µg L⁻¹ and 8.1% for 4-NP and 0.6 µg L⁻¹ and 3.7% for 4-t-OP, respectively. The proposed method was successfully applied in river water and effluent from a sewage-treatment plant, and the recoveries spiked at 6 µg L⁻¹ and 25 µg L⁻¹ levels were in the range of 82–113%.

Keywords:

• Room-temperature ionic liquid
• Liquid–liquid microextraction
• Nonylphenol
• Octylphenol

Acknowledgements

This work was supported by the National Natural Science Foundation of China (20377025).