Aim of the study:
A green and sustainable analytical method was developed for the extraction and etermination of Acid Black 703 dye in aqueous samples using a natural deep eutectic solvent (DES)-based liquid–liquid microextraction coupled with UV-vis spectrophotometry. The DES, composed of choline chloride and phenol, was employed as an environmentally benign extraction medium, replacing conventional toxic organic solvents.

Material and methods:
Critical experimental parameters, including pH, DES volume, sample-to-extractant ratio, and centrifugation time, were systematically optimized to maximize extraction efficiency.

Results and conclusions:
Under optimal conditions (pH 6, 1 mL DES, 2 min centrifugation), the method exhibited good linearity in the range of 10–60 ppm, with a limit of detection (LOD) of 2.47 μg/L, and a limit of quantification (LOQ) of 7.50 μg/L. The relative standard deviation (RSD) ranged from 2.35% to 3.21%, confirming method precision. Application to real water samples demonstrated satisfactory recovery and reproducibility, highlighting the method’s potential for routine monitoring of synthetic dyes in environmental matrices.