Development of liquid phase microextraction-based deep eutectic solvent for the extraction and determination of toxic metal ions in herbal medicines

Abstract

Herein, an eco-friendly, simple, and inexpensive procedure was developed using vortex-assisted combined with deep eutectic solvent-based liquid phase microextraction (VA-LPME-DES) followed by graphite furnace atomic absorption spectrometry. In the present procedure, DES was first synthesized from the combination of l-menthol and (1S)-(+)-camphor-10-sulfonic acid (CSA) in a molar ratio of 5:1, and then it was used as a green and safe extractant instead of common toxic organic solvents. The ability of the presented method was applied for the separation and preconcentration of lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As) in herbal medicines. After optimizing all the parameters of the experiment, the linear ranges were 0.10–200 µg kg⁻¹ with coefficient of determination (r²) better than 0.985. The limits of detection were in the ranges of 0.03–0.15 µg kg⁻¹. Relative standard deviation values for intra-day and inter-day of the method based on 7 replicate measurements were in the range of 1.8%–3.6% and 3.1%–7.3%, respectively. The relative recoveries of herbal medicines which have been spiked with different concentrations of metal ions were 91.5%–109.8%. The method was successfully used to analyze the heavy and toxic metals in herbal medicine samples.

Keywords:

• Vortex assisted
• liquid phase microextraction
• deep eutectic solvent
• heavy metals
• herbal medicines

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Tianjin Agricultural Science and Technology achievements transformation project “Technology Integration and Demonstration of Plant Extracts Replacing Antibiotic Compound Feed Additives” [Grant No. 202101160].