Integrated deep eutectic solvent-based air-assisted liquid-liquid microextraction with in situ derivatization for...

An integrated deep eutectic solvent-based air-assisted liquid-liquid microextraction method combined with in situ derivatization (DES-AA-LLME) was developed for the efficient extraction of desomorphine from biological samples, coupled with gas chromatography-nitrogen-phosphorus detection (GC-NPD) for its determination. The proposed approach integrated extraction and derivatization into a single step, thereby simplifying sample preparation. A hydrophobic deep eutectic solvent composed of menthol, choline chloride, and phenylacetic acid was used as the extraction phase, while ethyl chloroformate was applied for in situ derivatization. Rapid dispersion of DES microdroplets through repeated air-assisted aspiration-dispersion cycles enhanced mass transfer and derivatization efficiency. Under optimized conditions, the method exhibited linear ranges of 0.3-10 000 µg L^-1 and 0.6-10 000 µg L^-1 with coefficients of determination (R²) ≥ 0.9956. The limits of detection (LOD) and limits of quantification (LOQ) were 0.1-0.2 µg L^-1 and 0.3-0.6 µg L^-1, in water, plasma, and urine samples, respectively. The method showed satisfactory recoveries (92.1-93.8%) with relative standard deviations (RSDs, n = 5) < 6%. The proposed method demonstrated a satisfactory greenness profile and an acceptable environmental impact for monitoring desomorphine in urine and plasma samples.