Dispersed Liquid Phase Micro-extraction Of Anthraquinones Compounds In Complex Sample Enrichment, Enrichment And Chromatographic Analysis

PartⅠMechanisms and comparison of dispersive liquid phase micro-extraction based on organic solvent and ionic liquidIn this paper, mechanism of ionic liquid based dispersive liquid phase microextraction (ILDLPME) has been investigated; ILDLPME and organic solvent based dispersive liquid phase microextraction (OSDLPME) have been critically compared for the analysis of free anthraquinones in traditional Chinese medicines; dispersive liquid phase microextraction (DLPME) combined with HPLC has been developed for the determination of six free anthraquinones (aloe-emodin, rhein, danthron, emodin, chrysophanol and physcione). Under the optimal conditions, the enrichment factors (EFs) were in the range of 101～230 and 76～181 for OSDLPME and ILDLPME. The limits of detection were 20-200pg.ml-1 and 40-400pg.ml-1; the relative standard deviations (RSDs, n=3) were 3.1%～10.0% and 1.3%～7.0%; the recoveries of the analytes in four kinds of traditional Chinese medicines were 81.7%～110.7% and 81.9%～110.8% for OSDLPME and ILDLPME combined with HPLC. Ionic liquid was orderly arranged and molecular-ordered organized assembly formed, when ionic liquid dispersed in sample solution, then the analytes were extracted. Compared with OSDLPME, ILDLPME was more effective and more convenient, the repeatability of ILDLPME was better than that of OSDLPME. However, higher enrichment factors and a lower limits of detection could be obtained by OSDLPME. There were no significant deviations between two methods for the determination of free anthraquinones. PartⅡComparison of dispersive liquid-liquid microextraction based on organic solvent and ionic liquid combined with high performance liquid chromatography for analysis of emodin and its metabolites in urine samplesIn this paper, two methods based on organic solvent dispersive liquid-liquid microextraction (OS-DLLME) and ionic liquid dispersive liquid-liquid microextraction (IL-DLLME), coupled with high performance liquid chromatography, have been critically compared for analyzing emodin and its metabolites (aloe-emodin, anthraquinone-2-carboxylic acid, rhein, danthron, chrysophanol and physcion) in urine samples. Several important parameters influencing the extraction recoveries of DLLME such as the types and volumes of extraction solvent and disperser solvent, sample pH, extraction time, centrifugation time as well as salting-out effects were carefully optimized. Under such optimal conditions, the enrichment factors (EFs) for emodin and its metabolites by OS-DLLME and IL-DLLME were within the range of 90～295 and 63～192 respectively; their limits of detection were 70～400 pg/ml and 100～600 pg/ml; the relative standard deviations (RSDs, n=3) for intra-day and inter-day precision were lower than 7.2% and 8.7% by OS-DLLME, and lower than 5.7% and 6.4% by IL-DLLME; their recoveries of emodin and its metabolites were from 87.1% to 108% for OS-DLLME and from 87.5% to 106% for IL-DLLME when combined with HPLC respectively. Comparatively speaking, IL-DLLME was more convenient, less toxic and with better repeatability, but higher EFs and lower limits of detection could be obtained by OS-DLLME. There were no significant deviations between the two methods for the determination of emodin and its metabolites. From the results of HPLC/UV of urine sample after DLLME, the metabolites aloe-emodin, rhein, chrysophanol and physcion were identified by comparing the retention times with the standards; from the results of HPLC/MS, anthraquinone-2-carboxylic acid and danthron as unreported metabolites of emodin in urine samples were found.