Simultaneous determination of ten flavonoids of crude and wine‐processed Radix Scutellariae aqueous extracts in rat plasma by UPLC‐ESI‐MS/MS and its application to a comparative pharmacokinetic study

Radix Scutellariae (RS) is a herbal medicine with various pharmacological activities to treat inflammation, respiratory and gastrointestinal infections, etc. In this study, a rapid, sensitive and selective UPLC‐ESI‐MS/MS method was developed for simultaneous determination of 10 flavonoids – scutellarin, scutellarein, chrysin, wogonin, baicalein, apigenin, wogonoside, oroxylin A‐7‐O‐glucuronide, oroxylin A and baicalin – from RS aqueous extracts in rat plasma with propyl paraben as internal standard (IS). Chromatographic separation was achieved on a C₁₈ column using gradient elution with the mobile phase consisting of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The detection was performed in multiple reaction monitoring mode using electrospray ionization in negative mode. The validated method showed good linearity over a wide concentration range (r >0.9935). The intra‐ and interday assay variabilities were <9.5% and <12.4% for all analytes, respectively. The extraction recovery ranged from 71.2 to 89.7% for each analyte and IS. This method was successfully applied to pharmacokinetic comparision after oral administration of crude and wine‐processed RS aqueous extracts. There were significant differences in some pharmacokinetic parameters of most analytes between crude and wine‐processed RS. This suggested that wine‐processing exerted effects absorption of most flavonoids. Copyright © 2014 John Wiley & Sons, Ltd.     

A UFLC–MS/MS method for the simultaneous determination of eight bioactive constituents from red wine and dealcoholized red wine in rat plasma: Application to a comparative pharmacokinetic study

To explore whether alcohol has an effect on the pharmacokinetic behavior of phenolic acids, the main bioactive constituents in red wine, a highly sensitive and simple ultra‐fast liquid chromatography coupled with triple quadrupole mass spectrometry (UFLC–MS/MS) method was developed for simultaneous quantitation of eight phenolic acids in plasma samples. Plasma samples were extracted by liquid–liquid extraction and the chromatographic separation was achieved on a Zorbax SB‐C₁₈ column within 7.0 min. Results of the validated method revealed that all of the calibration curves displayed good linear regression (r > 0.99). The intra‐ and inter‐day precisions of the analytes were <14.0% and accuracies ranged from ?8.5 to 7.3%. The extraction recoveries of the analytes were from 71.2 to 110.2% and the matrix effects ranged from 86.2 to 105.5%. The stability of these compounds under various conditions satisfied the requirements of biological sample measurement. The method was successfully applied to a comparative pharmacokinetic study of phenolic acids in rat plasma. For gallic acid and gentisic acid, the parameters AUC_0–t and AUC_0–∞ increased remarkably (p < 0.05) after oral administration of red wine, which suggested that alcohol might enhance their absorption. This is the first report to compare the pharmacokinetic behavior of phenolic acids in red wine and dealcoholized red wine.     

Comparative analysis of the organic acid content of vinegar by capillary electrophoresis and ion-exclusion chromatography with conductimetric detection

Summary Ion-exclusion chromatography (IEC) and capillary electrophoresis (CE) have been compared for determination of organic acids in samples of Sherry wine vinegar. The accuracy of each technique was evaluated by use of the standard addition method. There were no differences between the techniques at a significance level of 5%, except for determination of malic acid by CE. Both analytical methods were used to analyse sixteen samples of Sherry wine vinegar supplied by different producers. The regression coefficients (r ²) for analysis by IEC and CE exceeded 0.94 for all acids. Results from both methods were in good agreement and the methods are sufficiently selective and sensitive to be applied directly to sherry wine vinegars.     

Determination of Polyphenols in Lycium barbarum Leaves by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

High-performance liquid chromatography coupled with high-resolution mass spectrometry was used for the determination of polyphenols in Lycium barbarum leaves. Twenty compounds extracted by methanol–water were tentatively identified that included chlorogenic acids, flavonoids, and phenolic acids. Neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, isochlorogenic acid B, isochlorogenic acid A, and isochlorogenic acid C were identified in Chinese cultivated L. barbarum leaves for the first time. Caffeic acid and isoquercitrin were also present. The concentrations of these compounds in L. barbarum leaves were determined. The results showed that all analytes had linear calibration relationships with limits of detection from 0.318 to 3.35?ng mL^?1. The polyphenols and flavonoids in L. barbarum leaves provided strong 2,2-diphenyl-1-picrylhydrazyl radical-scavenging capacity (IC₅₀ of 23.1?±?0.4 to 26.0?±?0.4?µg mL^?1). This method is suitable for the determination of polyphenols in L. barbarum leaves, which provide polyphenols with suitable antioxidant activity.     

Simultaneous determination of 20 components in red wine by LC‐MS: Application to variations of red wine components in decanting

The decanting of red wines has a long tradition in red wine service from the perspective of modifying the aroma or taste of a wine. A simple and sensitive liquid chromatography‐mass spectrometry method was developed for the simultaneous determination of 20 organic acids and polyphenols in decanting red wine. The separation was performed on a Diamonsil C₁₈ column (250 mm × 4.6 mm, 5 μm) using a mobile phase composed of methanol‐0.1% acetic acid under gradient elution. Analysis was performed in selected ion monitoring mode with negative electrospray ionization interface. All the linear regressions showed good linear relationships (r² > 0.9973) between the peak area and concentration of each marker. The assay was reproducible with overall intra and interday variation of less than 5.0%. The recoveries for the quantified compounds were observed over the range of 92.1–108.3% with RSD values less than 5.7%. The method developed was successfully applied to determine the variations of the 20 components in red wine after decanting in different conditions. Concentrations of most organic acids and polyphenols investigated in the red wine were decreased in decanting. In addition, increment of duration, temperature, and light intensity would intensify the changes.     

Quantitation of unbound sunitinib and its metabolite N-desethyl sunitinib (SU12662) in human plasma by equilibrium dialysis and liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study

A rapid, selective, and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous determination of unbound sunitinib and its active metabolite N‐desethyl sunitinib in plasma. Plasma and post‐dialysis buffer samples were extracted using a liquid–liquid extraction procedure with acetonitrile–n‐butylchloride (1:4, v/v). Chromatographic separation was achieved on a Waters X‐Terra® MS RP₁₈ column with a mobile phase consisting of acetonitrile and water (60:40, v/v) containing formic acid (0.1%, v/v) using an isocratic run, at a flow‐rate of 0.2 mL/min. Analytes were detected by electrospray tandem mass spectrometry in the selective reaction monitoring mode. Linear calibration curves were generated over the ranges 0.1–100 and 0.02–5 ng/mL for sunitinib and 0.2–200 and 0.04–10 ng/mL for N‐desethyl sunitinib in plasma and in phosphate‐buffered solution, respectively. The values for both within‐day and between‐day precision and accuracy were well within the generally accepted criteria for analytical methods. The analytical range was sufficient to determine the unbound and total concentrations of both analytes. The method was applied for measurement unbound concentrations in addition to total concentrations of sunitinib and its metabolite in plasma of a cancer patient receiving 50 mg daily dose. Copyright © 2012 John Wiley & Sons, Ltd.     

UHPLC–MS/MS quantification combined with chemometrics for the comparative analysis of different batches of raw and wine‐processed Dipsacus asper

A rapid and sensitive ultra‐high performance liquid chromatography with tandem mass spectrometry approach was established for the simultaneous determination of 4‐caffeoylquinic acid, loganic acid, chlorogenic acid, loganin, 3,5‐dicaffeoylquinic acid, dipsacoside B, asperosaponin VI, and sweroside in raw and wine‐processed Dipsacus asper . Chloramphenicol and glycyrrhetinic acid were employed as internal standards. The proposed approach was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery. Intra‐ and interassay variability for all analytes were 2.8–4.9 and 1.7–4.8%, respectively. The standard addition method determined recovery rates for each analytes (96.8–104.6%). In addition, the developed approach was applied to 20 batches of raw and wine‐processed samples of Dipsacus asper . Principle component analysis and partial least squares‐discriminate analysis revealed a clear separation between the raw group and wine‐processed group. After wine‐processing, the contents of loganic acid, chlorogenic acid, dipsacoside B, and asperosaponin VI were upregulated, while the contents of 3,5‐dicaffeoylquinic acid, 4‐caffeoylquinic acid, loganin, and sweroside were downregulated. Our results demonstrated that ultra‐high performance liquid chromatography with tandem mass spectrometry quantification combined with chemometrics is a viable method for quality evaluation of the raw Dipsacus asper and its wine‐processed products.     

Quantitative determination of bilobetin in rat plasma by HPLC–MS/MS and its application to a pharmacokinetic study

Although bilobetin, a biflavone isolated from the leaves of Ginkgo biloba, represents a variety of pharmacological activities, to date there have been no validated determination methods for bilobetin in biological samples. Thus, we developed a liquid chromatographic method using a tandem mass spectrometry for the determination of bilobetin in rat plasma. After protein precipitation with acetonitrile including diclofenac (internal standard), the analytes were chromatographed on a reversed-phased column with a mobile phase of purified water and acetonitrile (3:7, v/v, including 0.1% formic acid). The ion transitions of the precursor to the product ion were principally deprotonated ions [M − H]⁻ at m/z 551.2 → 519.2 for bilobetin and 296.1 → 251.7 for the IS. The accuracy and precision of the assay were in accordance with US Food and Drug Administration regulations for the validation of bioanalytical methods. This analytical method was successfully applied to monitor plasma concentrations of bilobetin over time following intravenous administration in rats.     

Chemical profile by LC–MS/MS,GC/MS and antioxidant activities of the essential oils and crude extracts of two Euphorbia species

In this study, it was aimed to investigate the chemical composition and antioxidant activities of two Euphorbia species. The major component of the fatty acid compositions obtained from the petroleum ether extracts was identified as palmitic acid for Euphorbia gaillardotii and Euphorbia macroclada. The main constituents of the essential oils were identified as arachidic acid for E. gaillardotii and tetratetracontane for E. macroclada. Among the 27 studied compounds, hesperidin, rutin, hyperoside and quinic, malic, gallic and tannic acids were found to be the most abundant compounds in the two Euphorbia species. The methanol extracts of E. gaillardotii and E. macroclada showed strong antioxidant activity in all tested methods. Particularly, IC₅₀ values of E. macroclada methanol extract that was the richest in terms of total phenolic-flavonoid contents were found to be lower than α-tocopherol and butylated hydroxytoluene in β-carotene bleaching, 2,2-diphenyl-1-picrylhydrazyl free and ABTS cation radical scavenging methods.     

A sensitive UPLC–MS/MS method for simultaneous determination of polyphenols and theaflavins in rat plasma: Application to a pharmacokinetic study of Da Hong Pao tea

A method based on ultra‐performance liquid chromatography–tandem mass spectrometry has been developed for the rapid and simultaneous determination of five catechins and four theaflavins in rat plasma using ethyl gallate as internal standard. The pharmacokinetic profiles of these compounds were compared after oral administration of five kinds of Da Hong Pao tea to rats. Biosamples processed with a mixture of β‐glucuronidase and sulfatase were extracted with ethyl acetate–isopropanol. Chromatographic separation was achieved by gradient elution using 10 mm HCOONH₄ solution and methanol as the mobile phase. Analytes were detected using negative ion electrospray ionization in multiple reaction monitoring mode. The lower limits of quantification were 1.0, 0.74 and 0.5 ng/mL for theaflavins, two catechins and three catechins, respectively. The validation parameters were well within acceptable limits. The average half‐lives (t_1/2) in blood of the reference solution group was much shorter than those of tea samples. The values of AUC_0–t and C_max of the polyphenols and theaflavins exhibited linear pharmacokinetic characteristics which were related to the dose concentration.     

Determination of cefuroxime lysine in rat brain microdialysates by ultra‐fast liquid chromatography with UV and tandem mass spectrometry: application to an acute toxicokinetic study

Cefuroxime lysine is a new second‐generation cephalosporins, which can penetrate the blood–brain barrier to cure the meningitis. In order to investigate its acute toxicokinetic study after intraperitoneal injection of 675 mg/kg cefuroxime lysine, a sensitive and clean ultra‐fast liquid chromatography–tandem mass spectrometry (UFLC‐MS/MS) method for the determination of cefuroxime lysine in microdialysate samples was developed and validated, which was compared with UFLC‐UV as a reference method. Chromatographic separation was performed on a Shim‐pack XR‐ODS C₁₈ column (75 × 3.0 mm, 2.2 µm), with an isocratic elution of 0.1% formic acid in acetonitrile–0.1% formic acid in water (45:55, v/v) for LC‐MS and acetonitrile–20 mm potassium dihydrogen phosphate (pH 3.0,20:80, v/v) for LC‐UV. The lower limit of detection was 0.01 µg/mL for LC‐MS and 0.1 µg/mL for LC‐UV method, with the same corresponding linearity range of 0.1–50 µg/mL. The intra‐ and inter‐day precisions (relative standard deviation) for both methods were from 1.1 to 8.9%, while the accuracy was all within ±10.9%. The results of both methods were finally compared using paired t‐test; the results indicated that the concentrations measured by the two methods correlated significantly (p < 0.05), which suggested that the two methods based on LC‐MS and LC‐UV were suitable for the acute toxicokinetic study. Copyright © 2014 John Wiley & Sons, Ltd.     

LC-MS/MS determination and pharmacokinetic study of albiflorin and paeoniflorin in rat plasma after oral administration of Radix Paeoniae Alba extract and Tang-Min-Ling-Wan

A rapid, sensitive and selective liquid chromatography/tandem mass spectrometry method (LC‐MS/MS) was developed and validated for simultaneous determination of albiflorin and paeoniflorin in rat plasma using geniposide as an internal standard. Plasma samples were extracted by solid‐phase extraction. Chromatographic separation was carried out on a Zorbax SB‐C₁₈ analytical column (150 × 2.1 mm × 5 µm) with 0.1% formic acid–acetonitrile (70:30, v/v) as the mobile phase. Detection was performed by multiple reaction monitoring mode using electrospray ionization in the positive ion mode. The total run time was 3.0 min between injections. The calibration curves were linear over a range of 1–1000 ng/mL for albiflorin and 2–2000 ng/mL for paeoniflorin. The overall precision and accuracy for all concentrations of quality controls and standards were better than 15%. Mean recovery was determined to be 87.7% for albiflorin and 88.8% for paeoniflorin. The validated method was successfully applied to the pharmacokinetic study of albiflorin and paeoniflorin in rat plasma after oral administration of Radix Paeoniae Alba extract and Tang‐Min‐Ling‐Wan. The pharmacokinetic parameters showed that albiflorin and paeoniflorin from Tang‐Min‐Ling‐Wan were absorbed more rapidly with higher concentrations in plasma than that from Radix Paeoniae Alba extract. The results provided a meaningful basis for evaluating the clinical applications of traditional Chinese medicine. Copyright © 2010 John Wiley & Sons, Ltd.     

LC‐MS/MS methods for the determination of edaravone and/or taurine in rat plasma and its application to a pharmacokinetic study

Three liquid chromatography–tandem mass spectrometry (LC‐MS/MS) methods were respectively developed and validated for the simultaneous or independent determination of taurine and edaravone in rat plasma using 3‐methyl‐1‐p‐tolyl‐5‐pyrazolone and sulfanilic acid as the internal standards (IS). Chromatographic separations were achieved on an Agilent Zorbax SB‐Aq (100 × 2.1 mm, 3.5 µm) column. Gradient 0.03% formic acid–methanol, isocratic 0.1% formic acid–methanol (90:10) and 0.02% formic acid–methanol (40:60) were respectively selected as the mobile phase for the simultaneous determination of two analytes, taurine or edaravone alone. The MS acquisition was performed in multiple reaction monitoring mode with a positive and negative electrospray ionization source. The mass transitions monitored were m/z [M + H]⁺ 175.1 → 133.0 and [M + H]⁺ 189.2 → 147.0 for edaravone and its IS, m/z [M ? H]^? 124.1 → 80.0 and [M ? H]^? 172.0 → 80.0 for taurine and its IS, respectively. The validated methods were successfully applied to study the pharmacokinetic interaction of taurine and edaravone in rats after independent intravenous administration and co‐administration with a single dose. Our collective results showed that there were no significant alterations on the main pharmacokinetic parameters (area under concentration–time curve, mean residence time, half‐life and clearance) of taurine and edaravone, implying that the proposed combination therapy was pharmacologically feasible. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous determination of caffeic acid and its major pharmacologically active metabolites in rat plasma by LC‐MS/MS and its application in pharmacokinetic study

A simple, sensitive and selective high‐performance liquid chromatography electrospray ionization tandem mass spectrometry (LC‐MS/MS) method was developed for simultaneous determination and pharmacokinetic study of caffeic acid (CA) and its active metabolites. The separation with isocratic elution used a mobile phase composed of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The detection of target compounds was done in selected reaction monitoring (SRM) mode. The SRM detection was operated in the negative electrospray ionization mode using the transitions m/z 179 ([M ? H]^?) → 135 for CA, m/z 193 ([M ? H]^?) → 134.8 for ferulic acid and isoferulic acid and m/z 153 ([M ? H]^?) → 108 for protocatechuic acid. The method was linear for all analytes over the investigated range with all correlation coefficients 0.9931. The lower limits of quantification were 5.0 ng/mL for analytes. The intra‐ and inter‐day precisions (relative standard deviation) were <5.86 and <6.52%, and accuracy (relative error) was between ?5.95 and 0.35% (n = 6). The developed method was applied to study the pharmacokinetics of CA and its major active metabolites in rat plasma after oral and intravenous administration of CA. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous determination of six index constituents and comparative analysis of four ethnomedicines from genus Gentiana using a UPLC‐UV‐MS method

Many species from genus Gentiana (Gentianaceae) have a long history of applications as folk medicines in the world. A simple rapid UPLC‐UV‐MS/MS method has been developed and validated for the simultaneous determination of six index constituents (gentiopicroside, swertiamarin, loganic acid, sweroside, mangiferin and ferulic acid) from the four ethnomedicines (G. rigescens Franch. ex Hemsl., G. rhodantha Franch. ex Hemsl., G. scabra Bunge and G. farreri Balf. f.). The UPLC analysis was performed on Shim‐Pack XR‐ODS III (150 × 2.0 mm, 2.2 µm). The mobile phase was consisted of acetonitrile–0.1% formic acid water using gradient elution. The wavelength 242 nm was chose for the four iridoids as well as mangiferin and 320 nm was set for ferulic acid. Mass spectrometry was applied for identification and quantification for analytes with low concentration. All the regression equations revealed a good linear relationship (R² > 0.9993). Accuracy and precision were all within the required limits. The chromatogram fingerprints analysis combined with principal component analysis showed the similarity values of the four species were <0.788 while the similarity values of G. scabra Bunge and G. rigescens Franch. ex Hemsl. were >0.993, which provided reasonable foundation for utilization and clinical application of the four ethnomedicines. This developed method appears to be a useful tool for quality control of the four ethnomedicines. Copyright © 2014 John Wiley & Sons, Ltd.     

Separation of Phenols from the Leaves of Toona Sinensis (Meliaceae) by Capillary Electrophoresis

A micellar electrokinetic capillary chromatography (MEKC) method, using UV detection, was developed for the determination of polyphenols in Toona sinensis (Meliaceae); the procedure involved precipitation of polyphenols from the leaves of T. sinensis using methanol. The structures can be established with fifteen compounds including methyl gallate, gallic acid, kaempferol, quercitin, quercitrin, rutin, kaempferol‐glucoside, catechin, epicatechin, stearic acid, palmitic acid, β‐sitosterol, stigmasterol, β‐sitosteryl‐glucoside, and stigmasteryl‐glucoside by spectroscopic analysis. However, there has been no investigation to quantitate the polyphenols that form T. sinensis. Thus, seven polyphenols of T. sinensis with UV absorbance, catechin (C), epicatechin (EC), methyl gallate (MG), rutin (R), gallic acid (G), quercitrin (Q), and kaempferol (K) were separated within 10 min with a 40 cm uncoated fused‐silica column, with the RSD < 3% (migration times), voltage at 15 kV using this method. On‐column detection was carried out at 254 nm. The detection limit of this method for all analytes ranged from 19.5 to 0.02 μM (RSD < 3.1%). The method provided a rapid and sensitive identification of polyphenols of interest in T. sinensis and is suitable for biological activity studies.     

Rapid determination of parabens in personal care products by stable isotope GC‐MS/MS with dynamic selected reaction monitoring

In this study, a rapid and sensitive analytical method for the determination of methyl‐, ethyl‐, propyl‐, and butyl esters of para‐hydroxy benzoic acid (parabens) in personal care products was developed and fully validated. Test portions were extracted with methanol followed by vortexing, sonication, centrifugation, and filtration without derivatization. The four parabens were quantified by GC‐MS/MS in the electron ionization mode. Four corresponding isotopically labeled parabens were selected as internal standards, which were added at the beginning of the sample preparation and used to correct for recovery and matrix effects. Sensitivity, extraction efficiency, and recovery of the respective analytes were evaluated. The coefficients of determination (r²) were all greater than 0.995 for the four parabens investigated. The recoveries ranged from 97 to 107% at three spiked levels and a one‐time (single) extraction efficiency greater than 97% was obtained. This method has been applied to screen 26 personal care products. This is the first time that a unique GC‐MS/MS method with dynamic selected reaction monitoring and confirmation of analytes has been used to determine these parabens in cosmetic personal care products.     

Stable isotope dilution analysis of wine fermentation products by HS-SPME-GC-MS

The aim of this study was to quantify, in a single analysis, 31 volatile fermentation-derived products that contribute to the aroma of red and white wine. We developed a multi-component method based on headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS). The 31 volatile compounds analysed include ethyl esters, acetates, acids and alcohols. Although these compounds have a range of functional groups, chemical properties, volatilities, affinities for the SPME fibre, and are found in wine at various concentrations, the accuracy of the analysis was achieved with the use of polydeuterated internal standards for stable isotope dilution analyses (SIDA). Nine of the labelled standards were commercially available, while 22 were synthesised. The method was validated by a series of duplicate spiked standard additions to model, white and red wine matrices over the concentration range relevant for each compound in wine. This demonstrated that the appropriate use of SIDA helped to account for matrix effects, for instance potential sources of variation such as the relative response to the MS detector, ionic strength, ethanol content and pH of different wine matrices. The resultant calibration functions had correlation coefficients (R²) ranging from 0.995 to 1.000. Each compound could be quantified at levels below its aroma threshold in wine. Relative standard deviations were all <5%. The method was optimised for the best compromise (over the 31 compounds) of wine dilution factor, level of sodium chloride addition, SPME fibre, SPME temperature, SPME time, GC column and MS conditions. Confirmation of identity was achieved by retention time and peak shape, and measurement of at least three ions for each analyte and internal standard with the MS operating in selected ion monitoring mode to facilitate more precise quantitation with a high sampling rate. The method is a valuable research tool with many relevant applications. A novel method for the combined chiral separation and SIDA quantification of 2- and 3-methylbutanoic acid is also demonstrated.     

The high throughput analysis of N-methyl carbamate pesticides in wine and juice by electrospray ionization liquid chromatography tandem mass spectrometry with direct sample injection into a short column

We developed a new analysis method for the N-methyl carbamate pesticides in juice and wine. The juice and wine were diluted with ultra pure water, and determined by electrospray ionization tandem mass spectrometry (ESI LC/MS/MS) with direct sample injection into a short column. The new method, including sample preparation and determination, is simple and rapid, and allows simultaneous determination of nine N-methyl carbamate pesticides in juice and wine within analysis time that is much shorter as compared with the traditional method. The average recoveries from juice and wine fortified at the level of 0.1 ppm ranged from 59.6 to 126.7% with the coefficients of variation ranging from 0.4 to 5.1% for intra-day (n = 5 × 3 days) and from 0.5 to 22.6% for inter-day (n = 15). At the fortified level of 0.5 ppm, the recoveries ranged from 69.3 to 127.2% with the coefficients of variation ranging from 0.4 to 6.9% for intra-day (n = 5 × 3 days) and from 0.5 to 22.6% for inter-day (n = 15). The method is considered to be satisfactory for the monitoring of the carbamate pesticides residues in juice and wine, suggesting that the present method is applicable to other pesticide residues in foods.     

Separation and identification of polyphenols in apple pomace by high-speed counter-current chromatography and high-performance liquid chromatography coupled with mass spectrometry

Apple pomace, a by-product in the processing of apple juice, was investigated as a potential source of polyphenols. Two methods of separation and purification of polyphenols from apple pomace extract were established by combination of gel chromatography with high-speed counter-current chromatography (HSCCC) and solvent extraction with HSCCC, respectively. The optimal separation was performed on a Sephadex LH-20 column using gradient aqueous ethanol as eluting solvent from 0% to 100% in increments of 10%. HPLC analysis indicated that main polyphenols existed in fractions eluted between 40% and 50% aqueous ethanol. The fractions of interest from column were separated by HSCCC with the solvent system hexane–ethyl acetate–1% aqueous acetic acid (0.5:9.5:10, v/v/v). Ethyl acetate fractionation of the apple pomace extract followed by direct HSCCC separation by the same solvent system in the volume ratio of 1:9:10 also produced a good separation of the main polyphenols of interest. Six high-purity polyphenols were achieved tentatively and identified by HPLC/MS: chlorogenic acid (1, m/z 354), quercetin-3-glucoside/quercetin-3-glacaside (2, m/z 464), quercetin-3-xyloside (3, m/z 434), phloridzin (4, m/z 436), quercetin-3-arabinoside (5, m/z 434), and quercetin-3-rhamnoside (6, m/z 448). These results provided a preliminary foundation for further development and exploration of apple pomace.