Cucurbituril and zwitterionic surfactant-based matrix solid-phase dispersion microextraction to simultaneously determine terpenoids from Radix Curcumae.

A rapid, efficient, and environmentally friendly matrix solid-phase dispersion microextraction was established to determine and quantify terpenoids in Radix Curcumae using ultra-high-performance liquid chromatography with a diode array detector. Various parameters affecting the extraction were investigated in detail, such as the grinding time, amount of adsorbent, type and concentration of elution solvent, and pH. The optimization of single-factor and response surface methodology was performed to confirm the best conditions in this procedure. The final optimized conditions were obtained by applying 70 mg of cucurbituril as adsorbent, 149 s as the optimum grinding time, and 228 mM of 3-(N,N-dimethylpalmitylammonio)propanesulfonate aqueous solution (pH 6.5) as the optimal elution solvent. The validated method showed a satisfactory linear range of 0.10-10 µg/mL for curdione and furanodiene, 0.01-10 µg/mL for isocurcumenol and germacrone, and 0.05-10 µg/mL for furanodienone, while the correlation coefficients ranged from 0.9945 to 0.9970. The recoveries of the investigated analytes at two spiked concentration levels (0.1 and 1.0 µg/mL) ranged from 96.53 to 104.60%. In addition, this method displayed acceptable reproducibility (relative standard deviation ≤ 3.66%). The results showed that the newly proposed matrix solid-phase dispersion microextraction method was successfully applied to analyze curdione, isocurcumenol, furanodienone, germacrone and furanodiene in Radix Curcumae samples.

In situ antioxidation-assisted matrix solid-phase dispersion microextraction and discrimination of chiral flavonoids from citrus fruit via ion mobility quadrupole time-of-flight high-resolution mass spectrometry.

A simple and sensitive in situ antioxidation process assisted with a matrix solid-phase dispersion method for extracting chiral flavonoids in citrus fruit was established, and samples were further analyzed using ion mobility quadrupole time-of-flight high-resolution mass spectrometry. The collision cross-sections of the target compounds were studied using single-field and stepped-field methods. The optimal conditions were obtained using 30 mg of C18 as a dispersant, methanol as an elution solvent and 0.6 mM 1,1-diphenyl-2-picrylhydrazyl (DPPH) as a radical solution. Additionally, the method showed satisfactory limits of detection (3.70-6.52 ng/mL) and good recoveries (96.78-104.67%) for four flavonoids in citrus fruit. The IC50 values of DPPH radical-scavenging activities ranged from 817.8 to 981.55 µg/mL for tested samples. The method was a good alternative for the microextraction and determination of antioxidant capacity and chiral differentiation of narirutin, naringin, hesperidin and neohesperidin in citrus fruit.

On-line concentration of triazine herbicides in microemulsion electrokinetic chromatography by electrokinetic injection assisted micelle to cyclodextrin stacking.

A fast, simple, environmentally friendly and sensitive on-line concentration method using microemulsion system as background solution (BGS) was developed for the trace detection of propazine, atrazine, simazine in food samples. The electrokinetic injection assisted micelle to cyclodextrin stacking (MCDS) was designed for the enrichment of target compounds. The factors affected enrichment performance, such as the kind of CDs, the amount of CDs, the concentration of methanol in BGS, the concentration of micelle in sample matrix, the concentration of phosphoric acid in BGS and the sample injection time were optimized. The optimized electrophoretic condition was obtained as following: 50 mM α-CD, 20 mM SDS in sample matrix., 80 mM PA and 20% MeOH (v/v) in BGS, sample solution by electrokinetic injection at -10 kV for 80 s. Under the optimized conditions described above, the linear range was 0.1-20 ug/mL with a good linear relationship with a correlation coefficient (r) ≥ 0.9985. The SEFs for the propazine, atrazine, simazine were found to be 123, 85 and 62 respectively. The proposed MCDS-MEEKC method provided an efficient method for trace analysis of triazine herbicides in honey and dendrobium officinale samples.

Micellar extraction with vesicle coated multi-walled carbon nanotubes to assist the dispersive micro-solid-phase extraction of natural phenols in Dendrobium.

Here, catanionic surfactant vesicles were prepared by varying the types and compositions of anions and cations and the number of alkyl tails of the surfactants. The formed vesicles were employed to disaggregate and stabilize multiwalled carbon nanotubes bundles in aqueous solutions. Furthermore, the vesicle coated carbon nanotubes were used as the adsorbent in the dispersive micro-solid phase extraction. Additionally, micellar extraction was employed for the sample pre-extraction to avoid the use of toxic organic extraction solvents. The relative parameters that affect the extraction efficiency of targets were optimized using response surface methodology. Under the optimal microextraction conditions, the analytical performance of the established method was evaluated. The limits of detection (2.3-13 ng/mL) and quantification (7.6-42 ng/mL), inter- and intra- day precision (1.2-4.0 %, 2.0-5.0 %), and spiked recovery values (80-91 %) were obtained. The proposed method showed high sensitivity, precision and trueness. It was successfully applied to analyze phenols in Dendrobium genus samples.

Simultaneous separation and concentration of neutral analytes by cyclodextrin assisted sweeping-micellar electrokinetic chromatography.

An on-line cyclodextrin assisted sweeping-micellar electrokinetic chromatography (CD assisted sweeping-MEKC) was developed for the simultaneous separation and concentration of four neutral analytes (erianin, dendrophenol, naringenin and scoparone) in Dendrobium officinale Kimura et Migo (D. officinale). The D. officinale was directly determined by this on-line stacking method after simple extraction and dilution. The optimized background solution (BGS) was 50 mM phosphoric acid (PA) containing 100 mM SDS and 30% (v/v) methanol. The best separation and concentration performance of analytes dissolved in 90 mM CD and 100 mM PA was achieved in a short analysis time when injected at 50 mbar for 100 s. Compared with conventional sweeping-MEKC and MEKC method, significant improvement in enrichment efficiency was achieved by using this proposed method. A series of validation studies of the present method was performed under the optimal conditions. Good linearities were obtained with the correlation coefficients in the range of 0.994-0.999, the detection limits were ranged from 13 to 40 ng/mL. Sensitivity enhancement factors (SEFs) were in the range of 28.5-46.8 compared with traditional injection (injection time 3 s). Therefore, the proposed method was successfully applied for the separation and concentration of neutral analytes in real samples.

Oxidative metabolism of typical phenolic compounds of Danshen by electrochemistry coupled to quadrupole time-of-flight tandem mass spectrometry.

An electrochemistry coupled to online quadrupole time-of-flight tandem mass spectrometry (EC/Q-TOF/MS) was applied to investigate the oxidative transformation and metabolic pathway of five phenolic acids in Danshen sample. Simulation of the phase I oxidative metabolism was carried out in an electrochemical reactor equipped with a glassy carbon working electrode. The phase II reactivity of the generated oxidative products towards biomolecules (such as glutathione) was investigated by ways of covalent adduct formation experiments. The results obtained by EC/MS were compared with well-known in vitro studies by conducting rat liver microsome incubations. Structures of the electrochemically produced metabolites were identified by accurate mass measurement and previously results in vivo metabolites. It was indicated that the electrochemical oxidation was in good accordance with similar products found in vivo experiments. In conclusion, this work confirmed that EC/Q-TOF/MS was a promising analytical tool in the prediction of metabolic transformations of functional foods.

Solid acids assisted matrix solid-phase dispersion microextraction of alkaloids by capillary electrophoresis coupled with quadrupole time-of-flight mass spectrometry.

The quantification of three alkaloids is important because quantitative study is a means of assessing the reliability of the experimental method, and three alkaloids of peimine, peiminine, and peimisine are main active ingredients in Chinese Pharmacopoeia 2015. An effective method based on the matrix solid-phase dispersion microextraction was developed for the extraction of alkaloid compounds in Fritillariae Thunbergii Bulbus. Target analytes were analyzed by capillary electrophoresis coupled with quadrupole time-of-flight mass spectrometry. The optimized experimental condition was that 50 mg Fritillariae Thunbergii Bulbus was blended homogeneously with 10 mg citric acid for 5 min. Two hundred microliters of water acidized by 1 mol/L hydrochloric acid (pH = 4.5) was selected to elute tested alkaloids. The results demonstrated that the investigated method had low limits of detection (1.32-1.59 ng/mL), good recoveries (86.63-98.12%), and reproducibility (relative standard deviations of peak areas < 0.87%). The proposed matrix solid-phase dispersion microextraction coupled with capillary electrophoresis combined with quadrupole time-of-flight mass spectrometry was successfully applied for the extraction of alkaloids in plants.