Xiaohong Bai

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

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.

Hollow fiber cell fishing with high-performance liquid chromatography for rapid screening and analysis of an antitumor-active protoberberine alkaloid group from Coptis chinensis.

A novel hollow fiber cell fishing procedure with high-performance liquid chromatography (HFCF-HPLC) was developed and used for rapid screening, fishing, and analysis of bioactive compounds from traditional Chinese medicines. Human breast cancer cell MCF7, mouse breast cancer cell MADB106, and gastric cancer cell SGC7901 were seeded on the internal surface of hollow fibers that were used to screen, fish, and analyze an antitumor-active protoberberine alkaloid group from Coptis chinensis decoction. The main variables that affect the HFCF-HPLC process were investigated and optimized. The surface properties of the hollow fiber-seeded cells, cell survival rate, non-specific binding between active centers in the hollow fiber and the target compounds, repeatability, reliability, and recovery of HFCF-HPLC were investigated in detail. Several active compounds structures that were screened from Coptis chinensis by using HFCF-HPLC were identified by comparing the retention time of the reference substances. The cell membrane and cell organelle were separated from MCF7 cells for a preliminary study of the target effect of active compounds on MCF7 cells. The living cell, cell membrane, and cell organelle fishing factors of the active compound, as the indexes of drug binding ability in HFCF-HPLC, were defined and discussed. In addition, tamoxifen as positive control substance and indomethacin as negative control substance were screened by using HFCF-HPLC to further verify the methods reliability. The results demonstrated that HFCF-HPLC is an effective, rapid, stable, and reliable method to screen and analyze bioactive compounds.

Simultaneous Preconcentration and Analysis of Anthraquinones Based on Ultrasound Emulsification Ionic Liquid Microextraction

An ultrasensitive method of ultrasound emulsification ionic liquid microextraction (UEILME) coupled with high-performance liquid chromatography (HPLC) has been developed and introduced for the preconcentration and analysis of anthraquinone additives in cosmetic samples and five anthraquinone compounds (aloe-emodin, rhein, emodin, chrysophanol and physcion) in traditional Chinese medicines. Several parameters affecting the extraction efficiency were investigated and optimized, such as the type and amount of extraction solvent, sample pH, ultrasound time and temperature, centrifugation speed and time and ionic strength. The most favorable results were obtained using 60 mg of 1-hexyl-3-methylimidazolium hexafluorophosphate as extraction solvent. The anthraquinones were extracted from the aqueous solution (pH 2.0) by ultrasound at 40°C for 7 min and centrifuged at 2,500 rpm for 6 min. Under optimal conditions, acceptable linearity of the five anthraquinone compounds was obtained with correlation coefficients > 0.99. The limits of detection (LODs) and limits of quantitation (LOQs) ranged from 0.01 to 0.09 µg/L and 0.05 to 0.25 µg/L, respectively. The relative standard deviations (n = 3) were less than 9.8%. Moreover, the enrichment factors ranged from 80 to 197-fold. Compared with conventional dispersive liquid-liquid microextraction, the UEILME technique exhibited lower LODs and LOQs. The results demonstrated that the UEILME coupled with HPLC is a simple, environmentally friendly, sensitive and efficient method for the extraction, concentration and analysis of anthraquinone compounds.

Hollow Fiber/Solvent Bar Microextraction Coupled with High Performance Liquid Chromatography for Preconcentration and Determination of Tanshinones and Salvianolic Acids in Radix Salvia miltiorrhiza

Hollow fiber solvent bar microextraction coupled with high-performance liquid chromatography was developed for the preconcentration and determination of active ingredients in Radix Salvia miltiorrhiza. These ingredients include dihydrotanshinone I, cryptotanshinone, tanshinone I, tanshinone IIA, salvianolic acid B, danshensu, and protocatechuic aldehyde. To evaluate the technique, seven compounds of varying polarity were used as model analytes, and a polyvinylidene fluoride hollow fiber (1.0 cm) with octanol (2 µL) was used as microextraction bar. The extraction conditions, including the identity of the hollow fiber, organic solvent, pH, salt addition, agitation speed, extraction time, and volume, were investigated and optimized. The extraction mechanism was analyzed and verified. The two main parameters, extraction recovery and enrichment factor, were obtained. Under the most favorable conditions, the enrichment factors of the analytes were 0.7–612, the limits of detection were below 1.11 ng mL−1, and the recoveries were between 95.4% and 101.3%. Thus, hollow fiber solvent bar microextraction is simple, rapid, and practical with a wide range of potential applications.

Analysis of emodin and its metabolites based on hollow fiber liquid phase microextraction

Hollow fiber liquid phase microextraction (HFLPME) coupled with high performance liquid chromatography (HPLC) has been developed to analyze the emodin and its metabolites in plasma and urine samples. The abilities of the absorption and metabolism for the active components in traditional Chinese medicines between the male and female rats were compared, and the biological metabolism and transmutation of the analyte were detailed discussed. Emodin and its metabolites in plasma and urine samples were extracted into n-octanol (acceptor) in hollow fiber. The acceptor phase was dried and dissolved by 50 microL methanol and then analyzed by HPLC. Under the optimal conditions, the linearities of the analytes were all very good in biological samples (r > 0.9960), the detection limits of the analytes were within the ranges of 0.1-3.0 microg/L. The enrichment factors were 12.2 to 26.3. The relative standard deviations for intra-day and inter-day precision were lower than 11.0%. The average recoveries of the analytes in plasma and urine samples were all in the range of 97.9% to 103%. HFLPME-HPLC can eliminate interference from complex biological samples, improve the sensitivity and reduce the detection limit, thus this method is suitable for the determination of trace compounds in complex sample.

Determination of Protoberberine Alkaloids in Coptis chinensis by Microextraction and High Performance Liquid Chromatography

Sample preparation technique based on an organic filter membrane (pH-resolved filter membrane microextraction) (pH-RFMME) was developed, coupled with high-performance liquid chromatography, and used to determine protoberberine alkaloids (jatrorrhizine, epiberberine, coptisine, palmatine, and berberine) in Coptis chinensis at different pH values through a one-step procedure. This green procedure provides a desirable sample pretreatment technology. The main variables affecting the extraction such as filter membrane area (or volumes of extraction solvents), sample pH, eluent pH, ionic strength, extraction stirring rate, extraction time, and sample volume were optimized. Under the optimized conditions, the enrichment factors of the analytes were 40.4–52.0, the linear ranges were 3.2–6250 ng · mL−1 for jatrorrhizine and epiberberine, 6.0–12000 ng · mL−1 for coptisine, 1.8–3600 ng · mL−1 for palmatine, and 18.8–18800 ng · mL−1 for berberine, with r 2 ≥ 0.9945. The limits of detection were less than 0.3 ng · mL−1. Satisfactory recoveries (84.8%–115.5%) and precision (1.8%–10.0%) were also achieved. These results confirmed that pH-RFMME is a simple, rapid, practical, and environmentally friendly method to isolate analytes that exhibit significant differences in acidity or alkalinity from complex samples.

Rapid Screening of Different Types of Antitumor Compound Groups from Traditional Chinese Medicine by Hollow Fiber Cell Fishing with High Performance Liquid Chromatography

A novel hollow fiber cell fishing with high performance liquid chromatography (HFCF-HPLC) was extended and used to screen flavonoid and anthraquinone active compound groups simultaneously from traditional Chinese medicines (TCMs). In this study, three cells (MCF-7, SGC7901, and MADB-106) were seeded on the inner wall of the hollow fiber employed to screen bioactive components from TCM water decoction. The variables influencing HFCFHPLC, such as cell seeding time, screening stirring rate and time, and active compound concentration, were investigated and optimized. The surface property of the hollow fiber seeded with cells, the cell survival rate under different conditions, the nonspecific binding between active centers in the fiber and the target compounds, and the repeatability and recovery of HFCF-HPLC were analyzed and validated. Certain structures of the compounds fished by HFCF-HPLC were identified after comparing the retention times of the reference substances. To verify preliminarily the binding site between the bioactive components and cells, we separated the cell membrane and cell organelle from live MCF-7 cells. We then employed the cell membrane, cell organelle, and the whole cells to screen simultaneously the active compounds. The cell fishing factor of the active compound was calculated and discussed as the index of cell-drug binding ability in HFCFHPLC. Tamoxifen as a positive control and indomethacin as a negative control were screened by HFCF-HPLC to verify the method. The results indicate that HFCF-HPLC is an effective and reliable method for the screening and analysis of bioactive components. Moreover, this method can be applied to predict bioactive candidates in TCMs.

Graphene‐sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii

A novel graphene-sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high-performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99-104%) and precision (1.1-10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii.

Novel multiple-solvent simultaneous microextraction for flavonoid and anthraquinone preconcentration in traditional Chinese medicine

In this study, a novel multiple-solvent simultaneous microextraction (MSSME) method is presented and introduced to preconcentrate flavonoids and anthraquinones from traditional Chinese medicines simultaneously. This technique was performed in one step by using two different solvents (immiscible with each other) carried by two filter membranes (1 cm × 1 cm), which were used as extraction devices. High-performance liquid chromatography with ultraviolet detection (HPLC/UV) was subsequently conducted. The wide exchange surface and multiple solvents respective extraction provided by the filter membrane showed that the proposed technique could be potentially applied as a sample pretreatment technology. The variables influencing MSSME, such as types of extraction solvents, filter membrane area (or volumes of extraction solvents), aqueous phase pH, ionic strength, extraction stirring rate, extraction time, and sample volume were investigated and optimized. Under optimized conditions, the enrichment factors of the analytes were 68 to 132 and the limits of detection were <0.96 ng mL−1. In addition, satisfactory recoveries of 80.1% to 119.2% and precisions of 2.2% to 8.8% were achieved. These results show that MSSME coupled with HPLC/UV is a simple, rapid, practical, and effective method to extract and preconcentrate different types of trace components from complex samples simultaneously.

Determination of protoberberine alkaloids in Coptidis Rhizoma by novel extraction and high-performance liquid chromatography

ABSTRACT An alternative, effective, and solvent-free microextraction method has been developed using weighing paper as the adsorbent for five protoberberine alkaloids from the methanolic extract of Coptidis Rhizoma (C. Rhizoma). Several variables influencing extraction efficiency were optimized. 1.0u2009×u20091.0u2009cm glassine weighing paper was employed for the isolation of the analytes followed by high-performance liquid chromatography. Under the optimum conditions, the limits of detection were between 0.2 and 0.4u2009ng/mL with enrichment factors from 41–47. The calibration curves were linear across the concentration ranges examined with correlation coefficients exceeding 0.992. All relative standard deviations were less than 10.0%. The method was employed for the determination of the analytes in C. Rhizoma. Berberine, palmatine, coptisine, epiberberine, and jatrorrhizine were present at concentrations between 9.62u2009±u20090.87u2009mg/g and 0.48u2009±u20090.05u2009mg/g.