Degradation study of rutin as template from magnetic composite molecularly imprinted polymer supernatant samples by liquid chromatography–mass spectrometry

Abstract

Compound structure change of the template molecule from rutin samples might affect the selectivity and adsorption of molecularly imprinted polymers based on magnetic halloysite nanotubes (MHNTs@MIPs). In the present study, not only MHNTs@MIPs were successfully characterized by TEM, SEM, EDS, FT-IR, TGA and VSM, but related compounds and potential degradation factors of template molecule rutin were also investigated in the polymerization and elution process of MHNTs@MIPs by high-performance liquid chromatography together with photodiode array and tandem mass spectrometry (HPLC-PDA-MS/MS) in negative ion mode. Nine flavonol components were detected in rutin active pharmaceutical ingredient samples, such as rutin, isoquercetrin, kaempferol-3-O-rutoside, isorhamnetin-3-O-rutoside, quercetin, kaempferol, isorhamnetin and two unknown triglycosides. Under acidic, basic, oxidative and solvent conditions, two common degradants with negative ESI-MS ions at m/z 317 and 349 were found. Meanwhile, protocatechuic acid and methyl ester were also observed as two characteristic oxidative degradants. Compared to above degradation results, rutin-dimethylsulfoxide adduct and oxidative degradant were observed in the synthesis supernatant, which demonstrated that appropriate solvents and strict control of the oxygen level were critical in the synthesis process. Therefore, degradation studies provide a solid foundation for the optimization of MHNT@MIP synthesis with rutin as a template, which can be potentially applied to other templates for further material performance investigation.