Slug Flow Liquid–Liquid Extraction of Deferiprone as Iron Complex Using Natural Deep Eutectic Solvents in a Cross-Flow T-Junction Microfluidic System

Herein, the application of a T-junction microfluidic droplet generator in slug flow liquid–liquid extraction (LLE) of deferiprone (DEF) was explored using Red-Green-Blue (RGB) analysis. The iron complex of deferiprone iron (DEF-Fe) exhibited a distinct color, enabling visual observation and RGB analysis for real-time monitoring of the extraction process within the microfluidic system. Six terpene- and fatty-acid-based deep eutectic solvents (DESs) were employed as cost-effective and environmentally friendly extractants for LLE. Furthermore, several parameters were investigated and optimized to enhance method performance. Under optimized conditions, the limits of detection for DEF were 0.7 mg L^–1 in water and 3.0 mg L^–1 in urine, with RSDs below 3.16%. Also, a good correlation was observed between the combined green and blue channel intensities (|G| + |B|) of the extractant and DEF concentration within the range of 1.0–60.0 mg L^–1 (R² ≥ 0.9901) in water and 5.0–75.0 mg L^–1 (R² ≥ 0.9899) in urine samples. The developed method was successfully applied to quantify DEF in pharmaceutical and urine samples, yielding relative recoveries of over 91.7%. A comparison with conventional LLE methods─including vortex-assisted, ultrasound-assisted, and batch extraction methods─demonstrated that the slug flow LLE method offers faster, online, and simpler extraction with superior performance.