title: Comparison of dispersive liquid-liquid microextraction based on organic solvent and ionic liquid combined with high-performance liquid chromatography for the analysis of emodin and its metabolites in urine samples.
abstract: In 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 were carefully optimized. Under 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; 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; the recoveries of emodin and its metabolites were from 87.1 to 105% for OS-DLLME and from 94.8 to 103% for IL-DLLME, respectively. 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 were found.
authors.affiliation: School of Pharmacy, Shanxi Medical University, Taiyuan, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Tian
authors.forename: Xuan
authors.initials: X
authors.lastname: Chen
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Bai
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004365:Drugs, Chinese Herbal / Q000032:analysis* / Q000302:isolation & purification* / Q000378:metabolism; D004642:Emodin / Q000302:isolation & purification* / Q000652:urine*; D052578:Ionic Liquids / Q000737:chemistry; D059627:Liquid Phase Microextraction / Q000295:instrumentation / Q000379:methods*; D008297:Male; D009930:Organic Chemicals / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004365:Drugs, Chinese Herbal; D052578:Ionic Liquids; D009930:Organic Chemicals; D004642:Emodin