One-step derivatization and temperature-controlled vortex-assisted liquid-liquid microextraction based on the solidification of floating deep eutectic solvents coupled to UV-Vis spectrophotometry for the rapid determination of total iron in water and food samples

In our work, hydrophobic thymol-based deep eutectic solvents (DESs) with strong reducibility, a lower density than water, and a slightly higher melting point than room temperature were synthesized. Based on these solid DESs, one-step derivatization and temperature-controlled vortex-assisted liquid-liquid microextraction based on the solidification of a floating DES (TC-VA-LLME-SFDES) via UV-Vis spectrophotometry for the rapid determination of total iron was developed. The derivatization and TC-VA-LLME were carried out simultaneously by the addition of DES as both the reducing agent and extraction solvent. After optimization, the calibration curve (5-250 mu g L-1, R-2 = 0.9982), limit of detection (1.5 mu g L-1), limit of quantitation (5.0 mu g L-1), precision (<= 4.0%) and enrichment factor (92) was obtained. This method was applied for the determination of total iron in water and food samples with satisfactory recoveries (85.4-106.2%). One-step derivatization and TC-VA-LLME only required 2 min. Furthermore, this method opened up the application of solid DESs in liquid-liquid microextraction.

Automated summary

In this work, hydrophobic thymol-based deep eutectic solvents (DESs) with strong reducibility, lower density than water, and slightly higher melting point than room temperature were synthesized. Based on these solid DESs, a one-step derivatization and temperature-controlled vortex-assisted liquid-liquid microextraction method (TC-VA-LLME-SFDES) via UV-Vis spectrophotometry for rapid determination of total iron was developed. The method showed good recovery and precision, and could be completed within 2 minutes.