| Two-dimensional liquid chromatography (2D-LC) has been widely used for the analysis of complex samples benefiting from its great improvement in separation selectivity and peak capacity. However, one 2D-LC system may not be enough to meet the separation requirements due to the complexity of certain samples and respective limitations of two separation modes. In this work, water extract of Scutellaria barbata D. Don, a traditional Chinese medicine, was fractionated into polar fraction and medium-polar fraction by means of solid phase extraction (SPE). An off-line 2D-HILIC/HILIC to analyze the polar fraction and an off-line 2D-HILIC/RPLC to analyze the medium-polar fraction were developed, respectively. Such double off-line 2D-LC systems enabled a comprehensive study of the components in Scutellaria barbata D. Don.2D-HILIC/HILIC was developed for the analysis of polar fraction in Scutellaria barbata D. Don. The columns were screened and the analytical conditions were optimized.206 peaks were detected from the polar fraction. The practical peak capacity was 2698 and the orthogonality reached 63.18%.2D-HILIC/RPLC was developed for the analysis of medium-polar fraction in Scutellaria barbata D. Don.543 peaks were detected from the medium-polar fraction. The practical peak capacity was 2879, and the orthogonality reached 90.62%. The results demonstrated that these two systems were highly orthogonal, and the peak capacities were greatly increased.By combination of 2D-HILIC/RPLC with MS, a total of 22 flavonoids were tentatively identified with the MS fragmentation rules, which represented a comprehensive characterization of Scutellaria barbata D. Don. |
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