Natural Thymol-tert-Butylhydroquinone-Based Deep Eutectic Solvent/Vortex-Assisted Dispersive Liquid-Liquid...

Area of Science:

• Analytical Chemistry
• Environmental Chemistry
• Green Chemistry

Background:

• Monitoring trace pesticide residues in water is a significant global analytical challenge.
• Existing methods often face limitations in sensitivity, cost, or environmental impact.
• Organophosphorus pesticides (OPPs) are widely used and pose risks to ecosystems and human health.

Purpose of the Study:

• To develop and validate a novel, sensitive, and eco-friendly method for the pre-concentration and analysis of OPPs in various water matrices.
• To utilize a bio-derived hydrophobic deep eutectic solvent (DES) for enhanced extraction efficiency.
• To couple the DES-based extraction with gas chromatography (GC) and micro electron capture detection (µECD).

Main Methods:

• Synthesis and characterization of a [thymol:tert-butylhydroquinone] (Thy:TBHQ) DES.
• Optimization of vortex-assisted dispersive liquid-liquid microextraction (DLLME) parameters including disperser solvent, sample volume, extraction time, and pH.
• Analysis of OPPs using gas chromatography with micro electron capture detection (GC-µECD).
• Validation of the method for linearity, limits of detection (LODs), limits of quantification (LOQs), and precision (RSD).
• Assessment of method performance in spiked real water samples (tap, river, seawater) and evaluation of DES reusability.

Main Results:

• The optimized method demonstrated excellent linearity (R² = 0.991-0.997) and achieved low LODs (3.44-15.43 ng L⁻¹) and LOQs (10.32-51.38 ng L⁻¹), below EU limits.
• High enrichment factors (13-27) and good precision (intra-day RSD < 3.79%, inter-day RSD < 9.66%) were obtained.
• Effective extraction and recovery were observed across different water matrices (tap, river, seawater), with recoveries ranging from ≈54% to 100%.
• The DES exhibited high reusability, retaining >85% performance over ≥9 cycles, indicating its stability and robustness.
• The extraction efficiency is attributed to synergistic interactions between aromatic OPPs and the DES.

Conclusions:

• The developed [Thy:TBHQ]-based vortex-assisted DLLME/GC-µECD method is a sensitive, precise, and reusable approach for monitoring trace OPPs in diverse water samples.
• This method offers a green alternative with reduced solvent consumption compared to traditional techniques.
• The findings highlight the potential of bio-derived DESs as effective extraction media for environmental analysis.