Deep eutectic solvent as stationary phase for flow analysis: Automated trace metal determination in food products

Area of Science:

• Analytical Chemistry
• Green Chemistry

Background:

• Deep eutectic solvents (DES) offer solutions for analytical chemistry challenges, particularly in microextraction.
• High viscosity of DES has limited their application in flow analysis.

Purpose of the Study:

• To develop a novel DES-based liquid-liquid microextraction approach for trace metal determination in foods.
• To integrate this approach into an automated flow analysis system.

Main Methods:

• Preparation and characterization of a thymol and thionalide DES.
• Use of COSMO-SAC model for predicting metal salt solubility.
• Application of DES as a stationary phase in a flow analysis extraction column.
• Automated extraction of metals from microwave-digested food samples.
• Elution with an aqueous thiourea solution.

Main Results:

• Successful application of a novel DES in an automated flow analysis system.
• Achieved low limits of detection for Hg (6 μg kg⁻¹), Cu (4 μg kg⁻¹), Pb (6 μg kg⁻¹), and Cd (0.6 μg kg⁻¹).

Conclusions:

• First application of a DES-based stationary phase in automated flow analysis.
• Significantly enhanced extraction efficiency for trace metals.
• Enables precise and reliable determination of trace metals in food products.
• Aligns with green chemistry principles by minimizing waste.