Homogeneous ionic liquid microextraction of the active constituents from fruits of Schisandra chinensis and Schisandra sphenanthera

Homogeneous ionic liquid microextraction (HILME) was developed for the extraction of schizandrin, schisantherin A and deoxyschizandrin from Schisandra chinensis and Schisandra sphenanthera. 1-Butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) aqueous solution was used as extraction solvent, and ammonium hexafluorophosphate ([NH4][PF6]) was used as ion-pairing agent. 1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]), which is barely soluble in water, was formed in situ, and was used as sample solution. High-performance liquid chromatography (HPLC) was employed for separation and determination of the analytes. The calibration curve showed good linear relationship (r > 0.9998). The recoveries were between 69.71% and 88.33% with RSDs lower than 4.86%. External standard method was adopted in the proposed method, and internal standard method was applied for the evaluation of the proposed method. The two methods were compared and the results indicated that the proposed method was acceptable and simple. The HILME is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and Soxhlet extraction. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.

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► The ionic liquid was used as extraction solvent and no volatile organic solvent was used.
► The proposed method represents lower expenditures of sample, extraction time and solvent, compared with conventional methods.
► [C4MIM][PF6] was prepared in situ.
► The homogeneous extraction was performed.