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Micellar Electrokinetic Capillary Chromatography (micellar + electrokinetic_capillary_chromatography)
Selected AbstractsCapillary Zone Electrophoresis and Micellar Electrokinetic Capillary Chromatography for Determining Water-Soluble Vitamins in Commercial Capsules and TabletsJOURNAL OF FOOD SCIENCE, Issue 1 2001S-C. Su ABSTRACT: A rapid method was developed for simultaneously determining thiamine, riboflavin, pyridoxine, nicotinamide, nicotinic acid, and ascorbic acid. It was tested on 15 samples. The peaks of all components were cleanly separated with good resolution by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MECC). CZE was performed with 0.02 M borate buffer, and MECC was performed with 4% acetonitrile in 0.02 M borate/phosphate buffer containing 0.1 M sodium dodecyl sulfate. Average recoveries for all components were 80.3% to 103.7% with coefficients of variation being less than 5%. Thiamine, nicotinic acid, and pyridoxine contents were consistent with those labeled on the packages, but nicotinamide, riboflavin, and ascorbic acid contents of some samples were less. [source] Micellar electrokinetic capillary chromatography of methylxanthines-containing beverages: discussion of the molecular species involvedJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2005Alicia B Pomilio Abstract Micellar electrokinetic capillary chromatography (MECC) experimental conditions were applied to 12 samples of methylxanthine-containing infusions of different commercial brands of yerba mate, coffee, tea and cocoa as well as two cola drinks. The best resolution in this mode of automated high-performance capillary electrophoresis (HPCE) was achieved here when using 15 kV voltage in an uncoated fused-silica capillary of 45 cm length (40 cm effective length), 50 mM sodium dodecylsulfate, 90 mM pH 8.5 borate buffer and UV detection. Theobromine, caffeine and theophylline were separated, and the peak splitting due to tautomeric species was observed. Experimental conditions were controlled, keeping constant the size of the elution window in each analysis. The limit of detection was less than 1 mg l,1, the limit of quantitation was 2.5 mg l,1 and the work range was 2.5,300 mg l,1. This HPCE,MECC system has proved suitable for the analysis/quality control of xanthines in beverages for consumption. Roles of various parameters as well as distinctly charged species of each xanthine and the origin of peak splitting in this MECC system are discussed. Copyright © 2004 Society of Chemical Industry [source] Determination of Reserpine in Urine by Capillary Electrophoresis with Electrochemiluminescence DetectionELECTROANALYSIS, Issue 3 2004Weidong Cao Abstract A fast and sensitive approach to detect reserpine in urine using micellar electrokinetic capillary chromatography with electrochemiluminescence (ECL) of Ru(bpy)32+ detection is described. Using a 25,,m i.d. capillary as separation column, the ECL detector was coupled to the capillary in the absence of an electric field decoupler. Field-amplified injection was used to minimize the effect of ionic strength in the sample and to achieve high sensitivity. In this way, the sample was analyzed directly without any pretreatment. The method was validated for reserpine in the urine over the range of 1×10,6,1×10,4,mol/L with a correlation coefficient of 0.996. The RSD for reserpine at a level of 5,,mol/L was 4.3%. The LOD (S/N=3) was estimated to be 7.0×10,8,mol/L. The average recoveries for 10,,mol/L reserpine spiked in human urine were 94%. [source] Field-amplified sample injection-micellar electrokinetic capillary chromatography for the analysis of bisphenol A, bisphenol F, and their diglycidyl ethers and derivatives in canned soft drinksELECTROPHORESIS, Issue 9 2010Héctor Gallart-Ayala Abstract Conditions were established for the separation and analysis of bisphenol A, bisphenol F, and their diglycidyl ethers by micellar electrokinetic capillary chromatography (MECC). Good resolution was obtained for all compounds, although in order to achieve the separation of ortho,ortho, ortho,para, and para,para isomers of bisphenol F diglycidyl ether (BFDGE), BFDGE·2H2O and BFDGE·2HCl, it was necessary to use a 25,,m id fused silica capillary. To increase sensitivity, a field-amplified sample injection (FASI)-MECC method was developed using 10,mM SDS solution as injection matrix and a 75,,m id fused silica capillary. Instrumental quality parameters such as LODs (<55,,g/L with standards), linearity (r2>0.999), and run-to-run and day-to-day precisions (RSD values lower than 12.5%) were determined. Finally, the suitability of the FASI-MECC method for the analysis of bisphenol A, bisphenol F, and their diglycidyl ethers in canned soft drinks was evaluated. Quantitation was performed by matrix-matched calibration using a plastic-bottled isotonic drink as matrix. The results showed that FASI-MECC is an economic method for the screening and quantitation of these kinds of compounds in soft drink beverages, with no loss of reproducibility, and effective at concentrations lower than the specific migration level values established by the European Union. [source] Determination of gaseous and particulate carbonyls in air by gradient-elution micellar electrokinetic capillary chromatographyELECTROPHORESIS, Issue 19 2008Hui Sun Abstract A new continuous-flow gradient-elution micellar electrokinetic capillary chromatography method is developed for the determination of airborne carbonyls after derivatization with 2,4-dinitrophenylhydrazine. A total of 16 carbonyls can be determined with detection limits ranging from 0.94 to 8.50,mg/L, working range from 4.72 to 346,mg/L, and repeatabilities (relative standard deviation, n=5) from 1.23 to 4.6% or 3.93 to 7.6% for migration time and peak area, respectively. Coupling with denuder-filter sampling, a preliminary survey has been conducted to determine gaseous and particulate carbonyls from air sampled at a roadside station. The method is shown to have sufficient sensitivity for 1-h sampling of ambient carbonyls with detection limits ranging from 0.045 to 1.2,,g/m3 and working range from 0.11 to 43.3,,g/m3 at a flow rate of 10,Lpm. The method requires minimal modification of commercially available capillary electrophoresis equipment and can differentiate gaseous and particulate carbonyls to provide essential information and objective data for adopting effective measures to combat the discharge of carbonyl compounds to the atmosphere. [source] Determination of biogenic amines in HeLa cell lysate by 6-oxy-(N -succinimidyl acetate)-9-(2',methoxycarbonyl) fluorescein and micellar electrokinetic capillary chromatography with laser-induced fluorescence detectionELECTROPHORESIS, Issue 4 2006Liwei Cao Abstract An MEKC-LIF method using 6-oxy-(N -succinimidyl acetate)-9-(2'-methoxy-carbonyl) fluorescein (SAMF) newly synthesized in our lab as a labeling reagent for the separation and determination of eight typical biogenic amines was proposed. After careful study of the derivatization condition such as pH value, reagent concentration, temperature, and reaction time, derivatization reaction was accomplished as quickly as 10,min with stable yield. Optimal separation of SAMF-labeled amines was achieved with a running buffer (pH,9.3) containing 30,mM boric acid, 25,mM SDS, and 20%,v/v ACN. The proposed method allowed biogenic amines to be determined with LODs as low as 0.25,2.5,nmol/L and RSD values from 0.4 to 4.5%. The present method has been successfully used to monitor biogenic amines in HeLa cells and fish samples. This study exploits the potential of MEKC-LIF with SAMF labeling as a tool for monitoring biogenic amines involved in complex physiological and behavioral processes in various matrices. [source] Method development and validation for the analysis of didanosine using micellar electrokinetic capillary chromatographyELECTROPHORESIS, Issue 21 2005Swapna Mallampati Abstract A selective MEKC method was developed for the analysis of didanosine in bulk samples. Successful separation of didanosine from 13 of its potential impurities, derived from the various synthetic preparation procedures, was achieved. As CZE gave poor separation selectivity, MEKC was preferable. The use of EKC allowed achievement of the separation in a significantly shorter time than conventional HPLC. An anionic long-chain surfactant, lithium dodecyl sulfate (LiDS), was used as the pseudostationary phase and sodium tetraborate buffer as the aqueous phase. In order to obtain the optimal conditions and to test the method robustness, a central composite response surface modeling experiment was performed. The optimized electrophoretic conditions include the use of an uncoated fused-silica capillary with a total length of 40,cm and an ID of 50,,m, a BGE containing 40,mM sodium tetraborate and 110,mM LiDS at pH,8.0, an applied voltage of 18.0,kV, and the capillary temperature maintained at 15°C. The method was found to be robust. The parameters for validation such as linearity, precision, and sensitivity are also reported. Three commercial bulk samples were analyzed with this system. [source] Analysis of lamotrigine and its metabolites in human plasma and urine by micellar electrokinetic capillary chromatographyELECTROPHORESIS, Issue 4-5 2005Vincenzo Pucci Abstract A reliable micellar electrokinetic capillary chromatographic method was developed and validated for the determination of lamotrigine and its metabolites in human plasma and urine. The variation of different parameters, such as pH of the background electrolyte (BGE) and Sodium dodecyl sulfate (SDS) concentration, were evaluated in order to find optimal conditions. Best separation of the analytes was achieved using a BGE composed of 10 mM borate and 50 mM SDS, pH 9.5; melatonin was selected as the internal standard. Isolation of lamotrigine and its metabolites from plasma and urine was accomplished with an original solid-phase extraction procedure using hydrophilic-lypophilic balance cartridges. Good absolute recovery data and satisfactory precision values were obtained. The calibration plots for lamotrigine and its metabolites were linear over the 1,20 ,g/mL concentration range. Sensitivity was satisfactory; the limits of detection and quantitation of lamotrigine were 500 ng/mL and 1 ,g/mL, respectively. The application of the method to real plasma samples from epileptic patients under therapy with lamotrigine gave good results in terms of accuracy and selectivity, and in agreement with those obtained with an high-performance liquid chromatography (HPLC) method.* [source] Rapid assessment of ,-asarone content of Acorus calamus by micellar electrokinetic capillary chromatographyELECTROPHORESIS, Issue 4-5 2005Kim M. Hanson Abstract This report outlines a rapid, reproducible method for the determination of ,-asarone, a known carcinogen, using micellar electrokinetic capillary chromatography (MEKC)-UV-vis absorbance and a simple alcohol extraction. The MEKC method is based on a running buffer comprised of 100,mM sodium dodecyl sulfate (SDS), pH,10. The method is reproducible and provides baseline separation of ,-asarone and ,-asarone. This protocol was used to determine the ,-asarone content of Acorus calamus rhizome of a diploid variety harvested from the wetlands of the United States and the triploid variety from India obtained commercially. The results indicate raw product that originated from India contained 4.4%,w/w ,-asarone, while that from the United States contained 0.2%,w/w ,-asarone. Neither sample contained detectable concentrations of ,-asarone. This is the first report of the use of MEKC to determine asarone in a natural source. [source] Identification of diphenhydramine metabolites in human urine by capillary electrophoresis-ion trap-mass spectrometryELECTROPHORESIS, Issue 10-11 2004Andrea Baldacci Abstract The identification of diphenhydramine (DH) metabolites that are frequently observed in the capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) analyses of alkaline liquid/liquid and solid-phase extracts of patient urines is demonstrated. Having standards for DH and diphenhydramine- N -oxide (DHNO), the presence of these two compounds could be confirmed in urines that were collected overnight after administration of 25 mg DH chloride. Using CZE coupled to ion-trap mass spectrometry (CE-MSn) with positive electrospray ionization and an acetate buffer at pH 5.6, the [M+H]+ ions of DH (m/z = 256), DHNO (m/z = 272), and nordiphenhydramine (NDH, m/z = 242) and their fragmentation to a common m/z 167 product ion (diphenylcarbinol moiety) was monitored. The data indicate that all three compounds are cations in an acidic environment, the migration order being NDH, DH, and DHNO. Data obtained under negative electrospray ionization conditions suggest the presence of diphenylmethoxyacetic acid-glycine amide ([M-H], ion of m/z 298 and fragmentation to m/z 254, loss of CO2), a metabolite that could tentatively be assigned to a characteristic peak observed in the MEKC electropherogram at alkaline pH. The data presented in this paper illustrate the value of using CE-MSn for identification of urinary drug metabolites for which no standards are available. [source] Violet light emitting diode-induced fluorescence detection combined with on-line sample concentration techniques for use in capillary electrophoresisELECTROPHORESIS, Issue 17 2003Chih-Hsin Tsai Abstract The first application of a violet light-emitting diode (LED) for fluorescence detection in capillary electrophoresis (CE) is described. The utility of violet LED (peak emission wavelength at 410 nm, , 2 mW) for fluorescence detection is demonstrated by examining reserpine and dopamine-labeled NDA (naphthalene-2,3-dicarboxaldehyde), respectively. The detection limit for reserpine was determined to be 2.5×10,6 M by normal micellar electrokinetic capillary chromatography (MEKC) and this was improved to 2.0×10,9 M and 2.0×10,10 M when sweeping-MEKC and cation-selective exhaustive injection (CSEI)-sweep-MEKC techniques were applied, respectively. In addition, the detection limit of NDA-labeled dopamine was determined to be 6.3×10,6 M by means of normal MEKC and this was improved to 3.0×10,8 M when the sweeping-MEKC mode was applied. [source] Determination of pentachlorophenol and tribromophenol in sawdust by ultrasound-assisted extraction and MEKCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6-7 2008Claudia Mardones Abstract An ultrasonic bar-assisted extraction and CE separation procedure for the determination of pentachlorophenol (PCP) and 2,4,6-tribromophenol (TBP) residues in sawdust was developed and applied. For this purpose, micellar electrokinetic capillary chromatography (MEKC) was used and compared with a GC/MS methodology. This methodology allowed the quantification of PCP and TBP in a concentration range of 2.5,12.0 mg/kg for TBP and 2.8,12.0 mg/kg for PCP. Different sample treatment processes were evaluated in order to extract these compounds from sawdust. Better results were obtained when the residues were extracted with ultrasound-assisted hexane, filtered, evaporated, dissolved in Na2CO3, and injected into the CE equipment. The optimal option for GC/MS was extraction with Na2CO3 followed by a derivation using acetic anhydride and liquid,liquid extraction with hexane. This method allowed the quantification of TBP and PCP in sawdust in a concentration range of 0.19,12.00 mg/kg and 0.14,12.00 mg/kg, respectively. The CE method was compared with the GC/MS as reference method. The results were shown to be statistically similar by both methods for PCP as well as for TBP. [source] Determination of diterpenoid triepoxides in Tripterygium wilfordii by micellar electrokinetic capillary chromatographyPHYTOCHEMICAL ANALYSIS, Issue 3 2003Xiurong Song Abstract A micellar electrokinetic capillary chromatographic (MEKC) method has been established for the identification and determination of diterpenoid triepoxides in the Chinese herb Tripterygium wilfordii Hook F. and its preparations. Studies of the influence of boric acid and borax buffer concentration and pH, and of sodium dodecylsulphate (SDS) concentration have been carried out, and the optimum separation for the triepoxides was achieved using 20,mM boric acid and 10,mM borax with 20,mM SDS as the running buffer. MEKC was found to exhibit good accuracy, precision and repeatability. The sensitivity of the assay was sufficient to monitor the three active components in T. wilfordii and its preparations. Copyright © 2003 John Wiley & Sons, Ltd. [source] On-line concentration by field-enhanced sample injection with reverse migrating micelles in micellar electrokinetic capillary chromatography for the analysis of coumarins from traditional Chinese medicine and human serumBIOMEDICAL CHROMATOGRAPHY, Issue 6 2010Ting-Fu Jiang Abstract In this work, a simple, reproducible and sensitive micellar electrokinetic chromatography method was developed for the separation and determination of three coumarins, imperatorin (IM), isoimperatorin (IO) and osthole (OS) from traditional Chinese medicine and human serum. Field-enhanced sample injection with reverse migrating micelles was used for on-line concentration of the coumarins. The optimum buffer contained 50,mM H3PO4, 160,mM sodium dodecyl sulfate, 20% acetonitrile and 15% 2-propanol, and the pH of buffer was 2.0. The sample solution was diluted with water containing 5,mM sodium dodecyl sulfate and injected for 15,s with ,8,kV after injection of 2,s water plug. The effects of concentrations of sodium dodecyl sulfate and organic modifier, the sample matrix, the injection time of water plug, the injection voltage and injection time of sample on the separation and stacking efficiency were investigated. Under the optimum conditions, the analytes were well separated and by optimizing the stacking conditions, about 93, 195 and 136 fold improvement in the detection sensitivity was obtained for IM, IO and OS. The contents of three coumarins in Angelica dahurica Benth, Radix Angelicae Pubescentis and Fructus Cnidii were successfully determined with satisfactory repeatability and recovery. The possibilities of using this method for the determination of three coumarins in spiked human serum were also tested. Copyright © 2009 John Wiley & Sons, Ltd. [source] Separation and determination of isoflavones in red clover by micellar electrokinetic capillary chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 9 2007Yu Zhang Abstract A micellar electrokinetic capillary chromatography (MECC) method has been developed for the determination of the four isoflavones, i.e. biochanin A, formononetin, genstein and daidzein in red clover (Trifolium Pratense L.). The effect of running buffer pH and concentration were investigated. An electrolyte composed of 30 mm borate, 20 mm sodium dodecyl sulfate (SDS) and 4 mg/mL HP- , -CD containing 5% (v/v) ethanol at pH 10.1 provides a satisfactory separation for all the analytes. The applied voltage was 25 kV, and the capillary temperature was kept constant at 25°C with a UV detection at 254 nm. The relative standard deviations (RSD) of the migration time and peak area were less than 1.73 and 3.94% (intra-day), and 2.29 and 4.38% (inter-day), respectively, under the optimized separation conditions. Regression equations revealed a good linear relationship between the peak area of each compound and its concentration. The contents of the four compounds in red clover were successfully determined with satisfactory repeatability and recovery. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||