Ionic liquids-based microwave-assisted extraction of active components from pigeon pea leaves for quantitative analysis

The present study aims to extract active components from pigeon pea leaves by ionic liquid-based microwave-assisted extraction (ILMAE) for quantitative analysis. Compared with ionic liquid-based heating extraction (ILHE) and ultrasonic-assisted extraction (ILUAE), ILMAE exhibited higher extraction efficiency. A series of 1-alkyl-3-methylimidazolium ILs with different anions and alkyl chain lengths of cations were investigated, and 1-butyl-3-methylimidazolium bromide ([C4MIM]Br) solution was selected as extractants. Subsequently, ILMAE parameters were optimized, and the optimized conditions were [C4MIM]Br concentration 0.75 M, extraction temperature 60 °C, solvent to solid ratio 12:1 mL/g, and irradiation time 7 min. Under the optimal conditions, the extraction efficiency increased by 11.0–38.9% compared with ILHR and ILUAE, and the recovery achieved more than 95.3%. Furthermore, a rapid analysis method, HPLC-DAD with an UPLC column, was established and validated. This method exhibited satisfactory linearity (r2 > 0.999), precision (RSD < 4.6%) and recovery (97.14–103.38%), and was successfully applied for the quantification of nine components in pigeon pea leaves within 25 min. The results obtained provide a fast and safe method for determination of active components in pigeon pea leaves.

► 1-Alkyl-3-methylimidazolium ILs as extractants of active components from pigeon pea leaves.
► ILMAE exhibited higher extraction efficiency.
► There is no report on simultaneous determination of flavonoids, stilbenes and coumarins in pigeon pea.