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Zone Electrophoresis (zone + electrophoresis)
Kinds of Zone Electrophoresis Terms modified by Zone Electrophoresis 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] Capillary Zone Electrophoresis of some organic acids in milk wheyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5 2003Francesca Buiarelli Abstract This paper describes a method for analysing some acids of milk whey by Capillary Zone Electrophoresis. After eliminating the whey proteins by ultrafiltration, the whey underwent electrophoretic separation in the presence of anodic electroosmotic flow. The following analytes were detected: citric, orotic, uric, and hippuric acids. A procedure is described for sample preparation and the operating conditions for electrophoretic capillary separation established. Finally, orotic acid is quantitatively determined. [source] Determination of iodide in samples with complex matrices by hyphenation of capillary isotachophoresis and zone electrophoresisELECTROPHORESIS, Issue 20 2007Pavla Pant Abstract A method has been developed for the determination of iodide in mineral water, seawater, cooking salt, serum, and urine based on hyphenation of capillary ITP and zone electrophoresis. A commercially available instrumentation for capillary ITP with column-switching system was used. ITP served for removal of chloride present in the analyzed samples in a ratio of 106,107:1 to iodide, zone electrophoresis was used for evaluation. Isotachophoretic separation proceeded in a capillary made of fluorinated ethylene,propylene copolymer of 0.8,mm id and 90,mm total length to the bifurcation point filled with a leading electrolyte (LE) composed of 8,mM HCl,+,16,mM ,-alanine (,-Ala),+,10% PVP,+,2.86,mM N2H4×2HCl, pH,3.2; and a terminating electrolyte composed of 8,mM H3PO4,+,16,mM ,-Ala,+,10% PVP,+,5,mM N2H4, pH,3.85 for all the matrices except seawater. For ITP of seawater the LE consisted of 50,mM HCl,+,100,mM ,-Ala,+,10% PVP +,2.86,mM N2H4×2HCl, pH,3.52. Distance of conductivity detector from the injection point and bifurcation point was 52 and 38,mm, respectively. Zone electrophoresis was performed in a capillary made of fused silica of 0.3,mm id and 160,mm total length filled with LE from isotachophoretic step. LODs reached for all matrices were 2,3×10,8,M concentration (2.5,4,,g/L) enabled monitoring of iodide in all analyzed samples with RSD 0.4,9.3%. Estimated concentrations of iodide in individual matrices were 10,6,10,8,M. [source] Analysis of amphetamine-type substances by capillary zone electrophoresis using capacitively coupled contactless conductivity detectionELECTROPHORESIS, Issue 15 2010Rochelle Epple Abstract CE with capacitively coupled contactless conductivity detection (C4D) was employed for the separation and detection of seven amphetamine analogues as well as amphetamine, dextroamphetamine, methamphetamine and 3,4-methylenedioxymethamphetamine. The separation electrolyte was 30,mM hydroxypropyl-,-cyclodextrin (HP,CD) in a 75,mM acetic acid+25,mM sodium acetate buffer adjusted to pH 4.55. Conductivity detection was compared with UV detection using this same electrolyte. Average detection limits for C4D and UV were 1.3 and 1.0,ppm, respectively. The effects of HP,CD concentration and BGE composition on the selectivity of the separation were also investigated. An illicit, street-grade sample of 3,4-methylenedioxymethamphetamine (Ecstasy) and a prescription dextroamphetamine tablet were also analysed. [source] Synthesis of poly(N, N -dimethylacrylamide)- block -poly(ethylene oxide)- block -poly(N, N -dimethylacrylamide) and its application for separation of proteins by capillary zone electrophoresisELECTROPHORESIS, Issue 10 2010Jing Xu Abstract A series of well-defined triblock copolymers, poly(N, N -dimethylacrylamide)- block -poly(ethylene oxide)- block -poly(N, N -dimethylacrylamide) (PDMA- b -PEO- b -PDMA) synthesized by atom transfer radical polymerization, were used as physical coatings for protein separation. A comparative study of EOF showed that the triblock copolymer presented good capillary coating ability and EOF efficient suppression. The effects of the Mr of PDMA block in PDMA- b -PEO- b -PDMA triblock copolymer and buffer pH on the separation of basic protein for CE were investigated. Moreover, the influence of the copolymer structure on separation of basic protein was studied by comparing the performance of PDMA- b -PEO- b -PDMA triblock copolymer with PEO- b -PDMA diblock copolymer. Furthermore, the triblock copolymer coating showed higher separation efficiency and better migration time repeatability than fused-silica capillary when used in protein mixture separation and milk powder samples separation, respectively. The results demonstrated that the triblock copolymer coatings would have a wide application in the field of protein separation. [source] Organic solvents in CEELECTROPHORESIS, Issue S1 2009Ernst Kenndler Abstract In this contribution some fundamental aspects are discussed serving for a critical reflection and elucidation of the role of organic solvents in CE. The implications of the solvent on the parameters governing peak resolution are discussed based on the concepts describing migration and zone broadening in capillary zone electrophoresis. This discussion includes the solvent-dependent influence of the ionic strength on the mobility. The role of the solvent on the plate number in case of the inevitable diffusional peak dispersion is outlined, and its effect on other peak broadening contributions is briefly examined. This paper also deals with the problems of conductance, applicable voltage and analysis time upon application of organic solvents, and tries to clarify some misunderstandings common in the literature. [source] Novel negatively charged tentacle-type polymer coating for on-line preconcentration of proteins in CEELECTROPHORESIS, Issue 4 2009Liang Xu Abstract A novel negatively charged tentacle-type polymer-coated capillary column was fabricated and applied for on-line extraction and preconcentration of proteins. The polymer coating was prepared by glycidyl-methacrylate graft polymerization in a silanized capillary column and the following sulfonic acid group functionalization. It had high surface area and offered high phase ratio for protein adsorption. In addition, the polymer-coated capillary column provided more stable EOF than a bare uncoated capillary. These features of the polymer coating facilitated the extraction of proteins through electrostatic interactions. This was used to extract proteins. The extracted analytes were then desorbed and focused by EOF in the direction opposite to the sample injection flow for subsequent CE. With this procedure, over 1500-fold sensitivity enhancement was realized for myoglobin (MB) as compared with a normal capillary zone electrophoresis. By comparison of the peak areas of the enriched protein, it was found that the polymer-coated column could capture proteins about 30 times more than the uncoated column. In addition, the separation of a protein mixture containing 0.4,,g/mL of MB and 0.4,,g/mL of insulin was demonstrated by the on-line preconcentration and electrophoretic separation with the polymer-coated column. [source] A simple and rapid CZE method for the analysis of mycophenolic acid and its phenol glucuronide metabolite in human serum,ELECTROPHORESIS, Issue 17 2008Kaname Ohyama Abstract A simple and rapid capillary electrophoretic method was developed for simultaneous determination of mycophenolic acid and its metabolite, phenol glucuronide, in human serum. The sample preparation in the proposed method required only the precipitation by acetonitrile. Separation was performed by capillary zone electrophoresis using 75,mM phosphate buffer (pH 7.5) as running buffer, an applied voltage of 10,kV, and UV detection at 217,nm. Each serum sample analysis was completed within 15,min. The optimized method demonstrated good performance concerning specificity, linearity (r>0.9955), accuracy (95.9,113%), precision (<6.4%) and enough sensitivity for therapeutic drug monitoring. This method was successfully applied to measurements of mycophenolic acid and mycophenolic acid glucuronide in renal transplant patient samples and was a useful alternative to high-performance liquid chromatography-based methods. [source] Cover Picture: Electrophoresis 8/2008ELECTROPHORESIS, Issue 8 2008Article first published online: 17 APR 200 Regular issues provide a wide range of research and review articles covering all aspects of electrophoresis. Here you will find cutting-edge articles on methods and theory, instrumentation, nucleic acids, CE and CEC, miniaturization and microfluidics, proteomics and two-dimensional electrophoresis. On April 2 Professor Hjertén celebrated his 80th birthday, and it is an honor to take this opportunity to congratulate him on this special occasion and at the same time on his fruitful work. Stellan Hjertén's distinguished personality in research and life makes this celebration very special. It is therefore appropriate to devote a separate laudation in ELECTROPHORESIS to his achievements through which he has attained renown within the separation science community: indeed, he is considered undoubtedly to be the "Father of Capillary Electrophoresis". Professor Hjertén's preliminary work with Arne Tiselius motivated him to commit his career to electrophoresis: the development of free zone electrophoresis certainly revolutionized separation science, and since the construction of the first "capillary electrophoresis" equipment, one of the most cited works in this field carries his name. His friends were very keen to contribute manuscripts to this Issue, covering almost all areas in which Professor Hjertén has worked in his distinguished career. [source] Determination of ethyl glucuronide in human serum by hyphenation of capillary isotachophoresis and zone electrophoresisELECTROPHORESIS, Issue 8 2008Michaela Nováková Abstract The determination of ethyl glucuronide (EtG), a marker of recent alcohol consumption, in human serum by hyphenation of capillary ITP (CITP) and CZE is reported. For CITP step, 1×10,2,M hydrochloric acid adjusted with ,-aminocaproic acid (EACA) to pH,4.4 was used as the leading electrolyte, and 1×10,2,M nicotinic acid with EACA, pH,4.4, was used as the terminating electrolyte (TE). All electrolytes contained 0.2% hydroxypropylcellulose to suppress electroosmosis. In CITP, EtG was separated from fast serum macrocomponents chloride, phosphate, lactate, and acetate. Zones of microcomponents including EtG that migrated between acetate and nicotinate were forwarded to the second capillary filled with a BGE identical with the TE. Conductivity detection was used in the CITP step. Sensitive detection in the CZE step was performed using indirect spectrophotometric detection at 254,nm. The assay is based on a 1:5 dilution of serum with deionized water and has a concentration LOD for EtG in diluted sample of 9.8×10,9,M. The method was used for the determination of EtG in sera of volunteers consuming alcohol. [source] Coupling of solid-phase microextraction continuous bed (monolithic) capillaries with capillary zone electrophoresis for direct analysis of drugs in biological fluids,ELECTROPHORESIS, Issue 8 2008Reda Jarmalavi Abstract Hyperlink robust biocompatible solid-phase microextraction (SPME) devices were prepared using continuous bed (monolithic) restricted-access media (RAM) as the SPME capillary insert. The RAM-based SPME approach was able to simultaneously separate proteins from a biological sample, while directly extracting the active components of caffeine, paracetamol and acetylsalicylic acid from the drug NeoCitramonum. The devices were interfaced with a CZE system and fully automated analysis for sample preconcentration, desorption, separation and quantification of analytes was evaluated. Comparative study of in-line coupled SPME,CZE using RAM and RP capillary inserts was carried out. Using an SPME (RAM) insert, the calculated caffeine, paracetamol and acetylsalicylic acid LODs in a bovine plasma sample were 0.3, 0.8 and 1.9,ng/mL, respectively. [source] Electrokinetic supercharging for highly efficient peptide preconcentration in capillary zone electrophoresisELECTROPHORESIS, Issue 7 2008Jean-Marc Busnel Abstract Electrokinetic supercharging has been integrated in CZE for the development of a highly sensitive methodology for protein tryptic digest analysis. A careful choice of the experimental conditions led to sensitivity enhancement factors between 1000 and 10,000 whilst maintaining a satisfactory resolution. Peptides in the low nanomolar concentration range have been detected despite the use of the poorly sensitive UV absorbance detection mode. The buffer system used in this study is fully suitable for coupling CE to MS. [source] Recent developments in CE and CEC of peptidesELECTROPHORESIS, Issue 1 2008Václav Ka, ka Dr. Abstract The article brings a comprehensive survey of recent developments and applications of high-performance capillary electromigration methods, zone electrophoresis, ITP, IEF, affinity electrophoresis, EKC, and electrochromatography, to analysis, preparation, and physicochemical characterization of peptides. New approaches to the theoretical description and experimental verification of electromigration behavior of peptides and to methodology of their separations, such as sample preparation, adsorption suppression, and detection, are presented. Novel developments in individual CE and CEC modes are shown and several types of their applications to peptide analysis are presented: conventional qualitative and quantitative analysis, purity control, determination in biomatrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid and sequence analysis, and peptide mapping of proteins. Some examples of micropreparative peptide separations are given and capabilities of CE and CEC techniques to provide important physicochemical characteristics of peptides are demonstrated. [source] Determination of iodide in samples with complex matrices by hyphenation of capillary isotachophoresis and zone electrophoresisELECTROPHORESIS, Issue 20 2007Pavla Pant Abstract A method has been developed for the determination of iodide in mineral water, seawater, cooking salt, serum, and urine based on hyphenation of capillary ITP and zone electrophoresis. A commercially available instrumentation for capillary ITP with column-switching system was used. ITP served for removal of chloride present in the analyzed samples in a ratio of 106,107:1 to iodide, zone electrophoresis was used for evaluation. Isotachophoretic separation proceeded in a capillary made of fluorinated ethylene,propylene copolymer of 0.8,mm id and 90,mm total length to the bifurcation point filled with a leading electrolyte (LE) composed of 8,mM HCl,+,16,mM ,-alanine (,-Ala),+,10% PVP,+,2.86,mM N2H4×2HCl, pH,3.2; and a terminating electrolyte composed of 8,mM H3PO4,+,16,mM ,-Ala,+,10% PVP,+,5,mM N2H4, pH,3.85 for all the matrices except seawater. For ITP of seawater the LE consisted of 50,mM HCl,+,100,mM ,-Ala,+,10% PVP +,2.86,mM N2H4×2HCl, pH,3.52. Distance of conductivity detector from the injection point and bifurcation point was 52 and 38,mm, respectively. Zone electrophoresis was performed in a capillary made of fused silica of 0.3,mm id and 160,mm total length filled with LE from isotachophoretic step. LODs reached for all matrices were 2,3×10,8,M concentration (2.5,4,,g/L) enabled monitoring of iodide in all analyzed samples with RSD 0.4,9.3%. Estimated concentrations of iodide in individual matrices were 10,6,10,8,M. [source] Enhanced separation of purine and pyrimidine bases using carboxylic multiwalled carbon nanotubes as additive in capillary zone electrophoresisELECTROPHORESIS, Issue 16 2006Xin Xiong Abstract This paper describes the enhanced separation of adenine (A), hypoxanthine (HX), 8-azaadenine (8-AA), thymine (T), cytosine (C), uracil (U) and guanine (G) by CZE dispersing carboxylic multiwalled carbon nanotubes (c-MWNTs) into the running buffer. The effect of important factors such as c-MWNT nanoparticle concentration, the acidity and concentration of running buffer, and separation voltage were investigated to acquire the optimum conditions. The seven purine and pyrimidine bases could be well separated within 16,min in a 35,cm effective length fused-silica capillary at a separation voltage of +8.0,kV in a 23,mM tetraborate buffer (pH,9.2) containing 8.0×10,5,g/mL c-MWNTs. Under the optimal conditions, the linear ranges were of 2,250,,g/mL for A (R2,=,0.995), 3,200,,g/mL for U (R2,=,0.990) and G (R2,=,0.992), 3,250,,g/mL for T (R2,=,0.998), 2,200,,g/mL for C (R2,=,0.985) and 4,200,,g/mL for HX (R2,=,0.988) and 8-AA (R2,=,0.990). The detection limits were 0.9,,g/mL for A (S/N,=,3), 2.4,,g/mL for U, 2.0,,g/mL for T, 1.5,,g/mL for C, 2.5,,g/mL for G and 3.0,,g/mL for HX and 8-AA. The proposed method was successfully applied for determining five purine and pyrimidine bases in yeast RNA. [source] Preparative capillary zone electrophoresis using a dynamic coated wide-bore capillaryELECTROPHORESIS, Issue 15 2006Mahmoud M. Yassine Abstract Preparative capillary zone electrophoresis separations of cytochrome,c from bovine and horse heart are performed efficiently in a surfactant-coated capillary. The surfactant, dimethylditetradecylammonium bromide (2C14DAB), effectively eliminated protein adsorption from the capillary surface, such that symmetrical peaks with efficiencies of 0.7,million plates/m were observed in 50-µm,id capillaries when low concentrations of protein were injected. At protein concentrations greater than 1,g/L, electromigration dispersion became the dominant source of band broadening and the peak shape distorted to triangular fronting. Matching of the mobility of the buffer co-ion to that of the cytochrome,c resulted in dramatic improvements in the efficiency and peak shape. Using 100,mM bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane phosphate buffer at pH,7.0 with a 100-µm,id capillary, the maximum sample loading capacity in a single run was 160,pmol (2.0,µg) of each protein. [source] Determination of tobacco-specific N -nitrosamines in rabbit serum by capillary zone electrophoresis and capillary electrophoresis-electrospray ionization-mass spectrometry with solid-phase extractionELECTROPHORESIS, Issue 11 2006Chenchen Li Abstract In this paper, we propose a new strategy for separation and determination of tobacco-specific N -nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE-MS associated with SPE. Six TSNAs: N'-nitrosonornicotine, N'-nitrosoanatabine, N'-nitrosoanabasine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH,2.5) and another with citrate buffer (pH,2.4), as well as a CE-MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE-MS method, an optimized sheath liquid consisted of methanol,water was used at a flow rate of 10,,L/min. With SPE procedure, our proposed CE-MS method was successfully applied to determine TSNAs after 15,min metabolism in rabbits. A comparison study between CZE and CE-MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE-MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC-MS, the new CE-MS method is expected to be an alternative to the LC-MS method and applied to study the metabolism of TSNAs. [source] Rapid and sensitive determination of phosphorus-containing amino acid herbicides in soil samples by capillary zone electrophoresis with diode laser-induced fluorescence detectionELECTROPHORESIS, Issue 23 2005Eva Orejuela Abstract A straightforward and sensitive method has been developed for the analysis of phosphorus-containing amino acid herbicides (glufosinate and aminomethylphosphonic acid, the major metabolite of glyphosate) in soil samples. For this purpose, the analytical features of two indocyanine fluorescent dyes, sulfoindocyanine succinimidyl ester (Cy5) and 1-ethyl-1-[5-(N -succinimidyl-oxycarbonyl)pentyl]-3,3,3,3-tetramethyl-indodicarbocyanine chloride, as labeling reagents for the determination of these herbicides by CZE with diode LIF detection were investigated. Practical aspects related to the labeling chemistry and CZE separation showed that the two probes behave similarly, Cy5 being the best choice for the determination of these herbicides on account of its higher sensitivity. The optimum procedure includes a derivatization step of the pesticides at 25°C for 30,min and direct injection to CZE analysis, which is conducted within about 14,min using ACN in the running buffer. The lowest detectable analyte concentration ranged from 0.025 to 0.18,µg/L with a precision of 3.6,5.4%. These results indicate that indocyanine fluorescence dyes are useful as rapid and sensitive labels for the determination of these herbicides when compared with typical fluorescein dyes such as FITC and 5-(4,6-dichloro- s -triazin-2-ylamino) fluorescein, because they provide faster labeling reactions even at room temperature and the excess of reagent practically does not interfere the determination. Finally, the Cy5 method was successfully applied to soil samples without a preliminary clean-up procedure, and the herbicides were measured without any interference from coexisting substances. The recoveries of these compounds in these samples at fortification levels of 100,500,ng/g were 90,93%. [source] Cloud point preconcentration prior to capillary zone electrophoresis: Simultaneous determination of platinum and palladium at trace levelsELECTROPHORESIS, Issue 18 2005Soledad Cerutti Professor Abstract The incorporation of a cloud point extraction (CPE) step prior to capillary electrophoresis (CE) for simultaneously determining platinum and palladium at sub-,g/L levels is presented and evaluated. The analytes were extracted as 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complexes, at pH,2.0, mediated by micelles of the nonionic surfactant polyethyleneglycolmono- p -nonylphenyl ether (PONPE 7.5). The separation,determination step was developed from 150,,L of the extracted surfactant-rich phase diluted with 50,,L of acetonitrile (ACN). An exhaustive study of the variables affecting the cloud point extraction with PONPE 7.5 and the CZE step was done. The type and composition of the background electrolytes (BGEs) were investigated with respect to separation selectivity, reproducibility, and stability. A BGE of 50,mM monobasic sodium phosphate containing 30% ACN, pH 4.53 was found to be optimal for the separation of metal chelates. Detection was performed at 576,nm. An enrichment factor of 250 was obtained for the preconcentration of 50,mL of sample solution. The detection limits for the preconcentration of 50,mL of sample were 0.04,,g/L for Pt and 0.08,,g/L for Pd. As an analytical demonstration, ultratrace concentrations of platinum and palladium were conveniently quantitated in spiked water and urine samples. [source] Combination of cationic surfactant-assisted solid-phase extraction with field-amplified sample stacking for highly sensitive analysis of chlorinated acid herbicides by capillary zone electrophoresisELECTROPHORESIS, Issue 18 2005Yan Xu Abstract This report describes a novel online field-amplified sample stacking (FASS) procedure to analyze 16 chlorinated acid herbicides. By using a poly(vinyl alcohol) (PVA)-coated capillary to reduce electroosmotic flow and introducing a methanol,water plug before sample loading, the sample injection time could be very long without loss of sample and separation efficiency. Under the optimized condition, the FASS procedure could provide great sensitivity enhancement (5000,10,000-fold) and satisfactory reproducibility (relative standard deviations of migration times less than 2.4%, relative standard deviations of peak areas less than 8.0%). Combined with cationic surfactant-assisted solid-phase extraction (CSA-SPE), the limit of detection of the herbicides ranged from 0.269 to 20.3,ppt, which are two orders lower than those of the US Environmental Protection Agency standard method 515.1. The CSA-SPE-FASS-CE method was successfully applied to the analysis of local pond water. [source] Comparison of methanol and acetonitrile as solvents for the separation of sertindole and its major metabolites by capillary zone electrophoresisELECTROPHORESIS, Issue 17 2005Xavier Subirats Abstract Sertindole (1-[2-[4-[5-chloro-1-(4-fluorophenyl)-1H -indol-3-yl]-1-piperidinyl]ethyl]-2-imidazolidinone), an atypical antipsychotic drug, was separated by capillary electrophoresis from its two main metabolites norsertindole and dehydrosertindole. The low solubility of the analytes in water (octanol-water partition coefficient is about 105) is overcome by the use of methanol (MeOH) and acetonitrile (ACN) as solvents for the background electrolyte (BGE). Mobilities were measured in BGEs with defined pH in a broad range. It was found that in MeOH the mobility of the analytes is mainly governed by acid,base equilibria, whereas in ACN other reactions like ion pairing and homoconjugation play a pronounced role and lead to a complex pattern of the mobility as function of the pH. However, separation can be obtained in less than 10,min in both solvent systems. [source] Poly(methacrylic acid-ethylene glycol dimethacrylate) monolith in-tube solid-phase microextraction applied to simultaneous analysis of some amphetamine derivatives in urine by capillary zone electrophoresisELECTROPHORESIS, Issue 16 2005Fang Wei Abstract A method based on in-tube solid-phase microextraction and capillary zone electrophoresis (CZE) was proposed for simultaneously determining four amphetamines (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxymethamphetamine) in urine. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column, which can provide sufficient extraction efficiency, was introduced for the extraction of amphetamines from urine samples. The hydrophobic main chains and acidic pendant groups of the monolithic column make it a superior material for extraction of basic analytes from aqueous matrix. After extraction, the samples were analyzed by CZE. The best separation was achieved using a buffer composed of 0.1,M disodium hydrogen phosphate (adjusted to pH,4.5 with 1,M hydrochloric acid) and 20% methanol v/v, with a temperature and voltage of 25°C and 20,kV, respectively. By applying electrokinetic injection with field-amplified sample stacking, detection limits of 25,34,µg/L were achieved. Excellent method of reproducibility was found over a linear range of 0.1,5,mg/L. Determination of these analytes from abusers' urine sample was also demonstrated. [source] Analysis of poly(amidoamine)-succinamic acid dendrimers by slab-gel electrophoresis and capillary zone electrophoresisELECTROPHORESIS, Issue 15 2005Xiangyang Shi Abstract Ethylenediamine (EDA)-core poly(amidoamine) (PAMAM) succinamic acid dendrimers (Ex.SAH, where x refers to the generation) were synthesized and analyzed by polyacrylamide gel electrophoresis (PAGE), size-exclusion chromatography (SEC), potentiometric acid-base titration, and capillary zone electrophoresis (CZE). Various generations (E1.SAH,E7.SAH) PAMAMs and a succinamic acid terminated core-shell tecto(dendrimer) (E5(E3.SAH)n) were first analyzed by PAGE. PAGE results show that the relative mobilities of generation,2 to generation,7 dendrimers decreased with the increasing number of generations. The molecular mass of a generation,5 core generation,3 shell tecto(dendrimer) (denoted as E5(E3.SAH)n) was determined to be between the Mw of E6.SAH and E7.SAH. CZE analysis allowed the evaluation of electrophoretic properties of given-generation dendrimers. The electrophoretic mobilities of individual generations PAMAM polyanions are similar, indicating that the separation mainly depends on their approximately identical charge/mass ratio. The E5(E3.SAH)n tectodendrimer had a lower electrophoretic mobility, which was consistent with its lower charge/mass ratio. The combination of PAGE and CZE analysis provides an alternative and effective way to characterize this group of PAMAM-succinamic acid dendrimers. [source] An ultrasensitive method for the determination of thiouracil and phenylthiouracil using capillary zone electrophoresis and laser-induced fluorescence detectionELECTROPHORESIS, Issue 12 2005Tomás Pérez-Ruiz Abstract This paper reports the development of a method based on capillary electrophoresis with laser-induced fluorescence detection for the simultaneous determination of thiouracil (TU) and phenylthiouracil (PhTU) with high sensitivity (nanomolar range, i.e., attomoles detected). After derivatization with 5-iodoacetamidofluorescein, the analytes were separated by capillary zone electrophoresis using 20,mM phosphate buffer (pH,10.0) and quantified by fluorescence detection. The linearity range, precision, recovery, and detection limits were determined, and the method was shown to be applicable for the determination of TU and PhTU in spiked feed samples and urine. [source] Rapid separation of protein isoforms by capillary zone electrophoresis with new dynamic coatingsELECTROPHORESIS, Issue 11 2005William W. P. Chang Abstract Many cellular functions are regulated through protein isoforms. Changes in the expression level or regulatory dysfunctions of isoforms often lead to developmental or pathological disorders. Isoforms are traditionally analyzed using techniques such as gel- or capillary-based isoelectric focusing. However, with proper electroosmotic flow (EOF) control, isoforms with small pI differences can also be analyzed using capillary zone electrophoresis (CZE). Here we demonstrate the ability to quickly resolve isoforms of three model proteins (bovine serum albumin, transferrin, ,1 -antitrypsin) in capillaries coated with novel dynamic coatings. The coatings allow reproducible EOF modulation in the cathodal direction to a level of 10 -9 m2V -1s -1. They also appear to inhibit protein adsorption to the capillary wall, making the isoform separations highly reproducible both in peak areas and apparent mobility. Isoforms of transferrin and ,1 -antitrypsin have been implicated in several human diseases. By coupling the CZE isoform separation with standard affinity capture assays, it may be possible to develop a cost-effective analytical platform for clinical diagnostics. [source] Analysis of the glucosinolate pattern of Arabidopsis thaliana seeds by capillary zone electrophoresis coupled to electrospray ionization-mass spectrometryELECTROPHORESIS, Issue 7-8 2005Gerhard Bringmann Abstract An easy and rapid method for the analysis of intact, non-desulfated glucosinolates by capillary zone electrophoresis (CZE) coupled to electrospray ionization-time of flight-mass spectrometry (ESI-TOF-MS) is described. Surprisingly, an electrolyte and a sheath liquid based on formic acid provided the best results. In this strongly acidic system, the glucosinolates were separated and detected as anions, resulting in an excellent selectivity. Thus, crude plant extracts could be analyzed without any interference of matrix constituents. The sensitivity together with mass accuracy and true isotopic pattern of the TOF-MS allowed identification of a broad series of glucosinolates in Arabidopsis thaliana seeds. [source] System zones in capillary zone electrophoresis: Moving boundaries caused by freely migrating hydrogen ionsELECTROPHORESIS, Issue 2 2005Jozef L. Beckers Abstract We demonstrate that system zones (SZs) can be expected in background electrolytes (BGEs) with a low buffer capacity. The mobilities of this type of SZ (mSZ) could be determined by calculations both based on a mathematical model and by a simulation program. The values of mSZ are increasing for decreasing buffer capacities and lower concentrations of the BGEs. For completely unbuffered BGEs with a pH below 7, the mSZ reached values up to 350×10,9 m2V,1s,1. This value indicates that the existence of this type of SZ originates from migrating hydrogen ions. Although both the mathematical model and simulation program do not consider the influence of the pH of the sample solution, experiments have shown that the pH of the sample solution is also very important. The lower the pH of the sample solution, the larger the mSZ in a specific BGE for cationic SZs. Using completely unbuffered BGEs the hydrogen ions present in the original sample start to migrate freely through the capillary tube with the mobility of a single hydrogen ion and cause stepwise disturbances in the base line of the detector trace. It is remarkable that this type of SZ appears not to affect the electromigration dispersion (EMD) in a strong way and so far only dips could be obtained experimentally. [source] Direct determination of gentamicin components by capillary electrophoresis with potential gradient detectionELECTROPHORESIS, Issue 1 2005LingLing Yuan Abstract A simple and fast method was developed to determine non-UV active compounds directly without derivatization. The usefulness of the method was demonstrated by detecting the major components in aminoglycoside antibiotic mixtures using capillary zone electrophoresis with potential gradient detection. Under optimized separation conditions (0.2 mM cetyltrimethylammonium bromide (CTAB), 1 mM ammonium citrate, pH 3.5), gentamicin was separated into three major peaks (C1, C1a, and C2+C2a) within 15 min. This method showed better sensitivity than other capillary electrophoresis (CE) methods for determining underivatized gentamicin. The linear range was from 10 to 500 ppm. Because of its good repeatability and simplicity, this new method could be a good alternative for the current assays given by US Pharmacopoeia and European Pharmacopoeia. [source] Importance of the counterion in optimization of a borate electrolyte system for analyses of anions in samples with complex matrices performed by capillary zone electrophoresisELECTROPHORESIS, Issue 20 2004Ludmila K, ivánková Abstract Borate buffers are common background electrolytes for analyses of anions in capillary zone electrophoresis. Usually, sodium borate at a given pH is used and this specification seems to be sufficient for a successful analysis. In this paper, we show that free migration of OH - may deteriorate the analysis of a typical anionic analysis of clinical samples due to uncontrolled migration of OH - throughout the systems of analyzed zones and may damage the stacking of anionic analytes of interest. We have proven that the use of ammonium borate may remedy the situation where the presence of ammonium may selectively stop the free migration of OH - ions, slow down their effective mobility and bring their safe behavior resulting in reproducible stacking of clinically important anions. Results of real analyses of human serum samples confirmed the proposed method and proved that substitution of sodium for ammonium in borate buffers offers reliable analyses of clinical samples having chloride as the bulk component. The experimental results given in this paper are supported also by computer simulation, which can not only support the positive results but also show the dynamics of the separation that is otherwise hidden to any detection possibilities. [source] Critical aspects of analysis of Micrococcus luteus, Neisseria cinerea, and Pseudomonas fluorescens by means of capillary electrophoresisELECTROPHORESIS, Issue 18-19 2004Verena Hoerr Abstract Within the frame of our study we investigated Microccocus luteus, Neisseria cinerea, and Pseudomonas fluorescens by means of capillary zone electrophoresis (CZE). They form chains and clusters on a different scale, which can be reflected in the electropherograms. A low buffer concentration of Tris-borate and Na2 EDTA containing a polymeric matrix of 0.0125% poly(ethylene) oxide (PEO) was used. Key factors were the standardization and optimization of CE conditions, buffer solution, and pretreatment of bacterial samples, which are not transferable to different bacterial strains, in general. The different compositions of the cell wall of on the one hand Gram-positive (M. luteus) and Gram-negative (N. cinerea) cocci and on the other hand Gram-negative, rod-shaped bacteria (P.fluorescens), are probably responsible for the different pretreatment conditions. [source] | |||||||||||||