Elution-extrusion countercurrent chromatography separation of six pairs of isomeric iridoids from Cornus officinalis Sieb. et Zucc. guided by ion current extraction in mass spectrometry

A mass spectrometry-guided elution-extrusion countercurrent chromatography protocol was developed to separate chemical components from Cornus officinalis Sieb. et Zucc. In this study, ion current extraction, a mass spectrometry-based data postacquisition method, was utilized to boost the separation power and scope of countercurrent chromatography technique. As a peak repicking and denoising tool, ion current extraction was carried out to process the liquid chromatography with mass spectrometry and the countercurrent chromatography with mass spectrometry data. So the target components were reacquired in the created extracted ion current patterns with enhanced responses and diminished background noise, which facilitated the distribution constant determination (by liquid chromatography with extracted ion current) and the targets fractionation (by countercurrent chromatography with extracted ion current). Under the guidance of the extracted ion currents of the target components and with the support of elution-extrusion mode in the countercurrent chromatography separation, six pairs of minor iridoid isomers were obtained in shortened experimental duration. Besides, a reciprocal shifted symmetry plot was established to represent the elution-extrusion countercurrent chromatography chromatogram. The results demonstrated the capability of the ion current extraction-guided elution-extrusion countercurrent chromatography protocol in discovery, analysis, and fractionation of low-concentration and structurally similar chemicals from a complicated sample.