218
Microwave Extraction and Solid-Phase Extraction
Wei et al. (2015) used the microwave extraction method for the extraction of four
flavonoids from Radix Scutellariae, and their extraction yields were 33, 9, 9, and
2 mg/g, respectively. Thirteen natural deep eutectic solvents were tested; choline
chloride/lactic acid (1:2 molar ratio) + 20% water (v/v) was selected because it was
the most suitable one for the simultaneous extraction of these compounds. Aqueous
ethanol 60% (v/v) was selected as reference extraction solvent. A solid-phase
extraction method was also applied where the natural deep eutectic solvent extraction solution was flowed through the column packed with ME-2 macroporous resin
for the separation of the flavonoids from the natural deep eutectic solvent solution.
Recovery yields of baicalin, wogonoside, baicalein, and wogonin were 84%, 80%,
85%, and 82%, respectively (Wei et al. 2015).
Fig. 6.12 Pipette-tip solid-phase extraction method where the sorbent is packed inside the end of
the syringe (in this case, the sorbent is the ternary deep eutectic solvent molecularly imprinted
polymer (TDES-MIP)). Each time the solution was sucked up into and out of micropipette type of
the needle containing the adsorbent by pulling and pushing the syringe, respectively. The extraction complex retained on the adsorbent was washed, eluted, and subjected to analysis
L. Nakhle et al.
Microwave Extraction and Solid-Phase Extraction
Wei et al. (2015) used the microwave extraction method for the extraction of four
flavonoids from Radix Scutellariae, and their extraction yields were 33, 9, 9, and
2 mg/g, respectively. Thirteen natural deep eutectic solvents were tested; choline
chloride/lactic acid (1:2 molar ratio) + 20% water (v/v) was selected because it was
the most suitable one for the simultaneous extraction of these compounds. Aqueous
ethanol 60% (v/v) was selected as reference extraction solvent. A solid-phase
extraction method was also applied where the natural deep eutectic solvent extraction solution was flowed through the column packed with ME-2 macroporous resin
for the separation of the flavonoids from the natural deep eutectic solvent solution.
Recovery yields of baicalin, wogonoside, baicalein, and wogonin were 84%, 80%,
85%, and 82%, respectively (Wei et al. 2015).
Fig. 6.12 Pipette-tip solid-phase extraction method where the sorbent is packed inside the end of
the syringe (in this case, the sorbent is the ternary deep eutectic solvent molecularly imprinted
polymer (TDES-MIP)). Each time the solution was sucked up into and out of micropipette type of
the needle containing the adsorbent by pulling and pushing the syringe, respectively. The extraction complex retained on the adsorbent was washed, eluted, and subjected to analysis
L. Nakhle et al.