title: Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction coupled with high performance liquid chromatography for sensitive determination of trace celastrol in urine.
abstract: Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (UA IL-DLLME) coupled with high-performance liquid chromatography (HPLC) has been developed for the determination of celastrol in human urine samples. In the microextraction procedure, ionic liquid (IL) was used as extraction solvent and dispersed into the aqueous sample solution as fine droplets by means of dispersive solvent and ultrasonication which promoted the analyte to migrate into IL phase more easily. Several important parameters affecting the extraction efficiency were studied and optimized, including the type and volume of extraction solvent and dispersive solvent, sample pH, ultrasonication time, cooling time, centrifugation time and salting-out effect. Under the optimized conditions, 110-fold enrichment factor was obtained and the limit of detection (LOD) was 1.6 μg/L at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 10-1000 μg/L for celastrol in human urine sample, with a correlation coefficient of 0.9980. Intra- and inter-assay precision were 0.43% and 2.78%, respectively. The proposed method was successfully applied to the real human urine samples and good spiked recoveries in the range of 93.2-109.3% were obtained.
authors.affiliation: Key Laboratory of Chemistry of Northwestern Plant Resources, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, People's Republic of China.
authors.forename: Jian-Nan
authors.initials: JN
authors.lastname: Sun
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Shi
authors.forename: Juan
authors.initials: J
authors.lastname: Chen
mesh_terms: D002498:Centrifugation; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry; D016014:Linear Models; D059627:Liquid Phase Microextraction / Q000379:methods*; D053978:Pentacyclic Triterpenes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012965:Sodium Chloride; D013010:Sonication / Q000379:methods*; D014315:Triterpenes / Q000302:isolation & purification / Q000652:urine*
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; D012965:Sodium Chloride; C050414:celastrol