The separation and purification of biologically-active compounds from natural sources is of interest because such molecules find wide application in the pharmaceutical sector and in other industrial areas. Roselle (Hibiscus sabdariffa) plants are a good source of anthocyanins, flavonoids, hydroxycitric acid, tartaric acid, ascorbic acid and hibiscus acid. The separation of hibiscus acid from the Roselle extract is very challenging, requiring the use of selective methods. It is accomplished here by means of the indium-bearing Metal Organic Framework MIL-68-NH2. Before and after exposure to MIL-68-NH2, the Roselle extract is analyzed by thin-layer chromatography, ultraviolet-visible spectrophotometry, gas chromatography-mass spectrometry, and high-performance liquid chromatography. The structural integrity of MIL-68-NH2 after the separations is investigated by powder X-ray diffraction, nuclear magnetic resonance and infrared spectroscopy, confirming the adsorption selectivity of MIL-68-NH2 towards hibiscus acid.
Keywords: GC–MS; MIL-68-NH(2); Purification of hibiscus acid; Roselle extract; Selective adsorption.
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