Development of an eco-friendly liquid-liquid preconcentration method for the direct determination of herbicides in...

A natural deep eutectic solvent liquid-liquid microextraction method (NADES-LLME) for herbicide preconcentration from sugarcane juice, rapadura, and syrup, followed by HPLC-DAD analysis, is presented in this study. DSC analyses confirmed successful NADES formation. The method involves vortex-assisted preconcentration for 1 min (40.0 mL, pH 6.5, 10 % NaCl (w/v)) using 100 μL of hydrophobic NADES (menthol: acetic acid, 2:1 M ratio). ¹H NMR analysis confirmed that menthol acted as the extractor solvent, with acetic acid remaining in the aqueous phase. High preconcentration factors (60-182.9) and low limits of quantification (LOQs) ranging from 0.19 to 0.62 μg L^-1 were achieved. The feasibility of the method was confirmed by sample analysis, with recovery values ranging from 94 % to 110 %. Ametryn was detected in rapadura (94.8 μg Kg^-1) and syrup (85.4 μg Kg^-1), confirmed by HPLC-QTOF/MS. In conclusion, the NADES-based method offers a simple, eco-friendly, and effective alternative for herbicide analysis in sugarcane-derived products.