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Double-templated molecularly imprinted polymers with specific recognition of three matrine-type alkaloids were prepared using matrine and oxymatrine as the template molecules. An approach based on double-templated molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography and tandem mass spectrometry was then developed to extract and purify matrine, oxymatrine, and sophocarpine from Sophora moorcroftiana in the Tibetan plateau herbs. The polymers were characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. Their adsorption characteristics were evaluated using adsorption kinetics, isotherms, selectivity, and recycling experiments. This polymer exhibited excellent molecular recognition ability and good selectivity. The obtained polymers as adsorbent was further used for the determination of three matrine-type alkaloids coupled to high-performance liquid chromatography with tandem mass spectrometry, the recoveries of three matrines spiked at three concentration levels in samples were 73.25-98.42% (n = 5) with a relative standard deviation less than 6.82%. The limits of detection for the method were 9.23-15.42 μg/kg (S/N = 3). This proposed method was assessed to be an effective method for simultaneous extraction, isolation, and identification of matrine, oxymatrine, and sophocarpine from Sophora moorcroftiana.

A dummy molecularly imprinted polymer (d-MIP) was developed for extraction and cleanup of farrerol from Rhododendron aganniphum. The d-MIP was prepared by precipitation polymerization using quercetin as the dummy template, 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and acetonitrile as the porogen. The d-MIP was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. Dynamic curves, adsorption isotherms, and Scatchard plots showed the d-MIP had good affinity, capacity, and selectivity for the target compound. The prepared d-MIP was used as a sorbent in solid-phase extraction cartridges and successfully applied to specific extraction and purification of farrerol from real samples. High recoveries were obtained for four spiked levels of farrerol in Rhododendron aganniphum using d-MIP solid-phase extraction coupled with high-performance liquid chromatography. The linear range was 1-100 µg mL −1 , the limit of detection was 2.23 mg kg −1 , the farrerol recovery range was 85.7%-104.1%, and the relative standard deviations (n = 3) were all less than 2.2% for real samples. The proposed method provides a simple, rapid, and environmentally friendly approach to the analysis of farrerol in complex herbal products.

The minor constituent found in Acanthus ilicifolius Linnaeus, 4-hydroxy-2 (3H) benzoxazolone alkaloid (HBOA), has a range of versatile applications. Herein, a quick and straightforward method for extracting HBOA from A. ilicifolius Linnaeus was proposed. HBOA was used as a template, whereas methacrylic acid, ethylene glycol dimethacrylate, and acetonitrile were used as functional monomers, cross-linkers, and porogens, respectively. Molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization, and their adsorption isotherms, dynamics, and selective binding ability were characterized and analyzed. The results showed that the adsorption amount of the template was 90.18 mg/g. The MIPs were used as solid-phase extraction fillers and actual sample extraction columns, with a linear range of 0–100 μg/L, average recovery of 78.50–101.12%, and a relative standard deviation of 1.20–3.26%. The HBOA concentrations in the roots, stems, and leaves were 1,226, 557, and 205 μg/g, respectively. In addition, MIP–SPE was successfully used in isolating and purifying HBOA from different parts of A. ilicifolius Linnaeus, indicating its effectiveness in extracting and determining HBOA in other herbs.