Search results for "CAPILLARY ELECTROPHORESIS"
showing 10 items of 131 documents
Miniaturized liquid chromatography coupled on-line to in-tube solid-phase microextraction for characterization of metallic nanoparticles using plasmo…
2018
Abstract This tutorial aims at providing guidelines for analyzing metallic nanoparticles (NPs) and their dispersions by using methods based on miniaturized liquid chromatography with diode array detection (MinLC-DAD) and coupled on-line to in-tube solid-phase microextraction (IT-SPME). Some practical advice and considerations are given for obtaining reliable results. In addition, this work outlines the potential applications that set these methodologies apart from microscopy-related techniques, dynamic light scattering, single particle ICP-MS, capillary electrophoresis, field-flow fractionation and other chromatographic configurations, which are discussed and mainly seek to accomplish size …
Determination of organic contaminants in food by capillary electrophoresis
2005
This review addresses recent advances in the analysis of organic contaminants, such as antibiotics, pesticides, biological toxins, and food-borne pathogens, in foods by capillary electrophoresis (CE). Special attention is paid to those aspects that increase sensitivity and/or selectivity, such as sample extraction and concentration, on-line preconcentration techniques (stacking), affinity capillaries or/and specific detectors (laser induced fluorescence (LIF), mass spectrometry (MS)). The various CE modes used to separate the compounds and the quantification strategies are also examined. As a result, this work presents an updated overview on the principal applications of CE, together with a…
Prediction of wheat dough W and P/L inflation test parameters by capillary zone electrophoresis of a protein extract followed by multivariate regress…
2004
A procedure for the evaluation of the wheat flour hardness, based on capillary electrophoresis of a protein extract in an isoelectric acidic buffer, was developed. The 13 flour samples were extracted twice, and two injections of each extract were made. Separations were performed in a background electrolyte (BGE) containing 40 mM aspartic acid, 6 M urea, and 0.5% hydroxyethylcellulose at 60 degrees C. Using the normalized and corrected areas of 79 peaks and peak groups, a partial least squares regression (PLS1) model was able to predict the flour strength or dough deformation work (W) and the dough tenacity/extensibility ratio (P/L) (Alveograph parameters) with an average relative standard d…
Ionic liquids in separation techniques.
2007
The growing interest in ionic liquids (ILs) has resulted in an exponentially increasing production of analytical applications. The potential of ILs in chemistry is related to their unique properties as non-molecular solvents: a negligible vapor pressure associated to a high thermal stability. ILs found uses in different sub-disciplines of analytical chemistry. After drawing a rapid picture of the physicochemical properties of selected ILs, this review focuses on their use in separation techniques: gas chromatography (GC), liquid chromatography (LC) and electrophoretic methods (CE). In LC and CE, ILs are not used as pure solvents, but rather diluted in aqueous solutions. In this situation IL…
Separation of selected peptides by capillary electroendoosmotic chromatography using 3 μm reversed-phase bonded silica and mixed-mode phases
1999
The retention behaviour and selectivity of selected basic, neutral and acidic peptides have been studied by capillary electroendoosmotic chromatography (CEC) with Hypersil C8, C18, Hypersil mixed-mode, and Spherisorb C18/SCX columns, 250 (335) mm x 100 microns, packed with 3 microns particles, and eluted with mobile phases composed of acetonitrile-triethylamine-phosphoric acid (TEAP) at pH 3.0 using a Hewlett-Packard Model HP3DCE capillary electrophoresis system. The selected peptides were desmopressin (D), two analogues (A and B) of desmopressin, oxytocin (O) and carbetocin (C). The peptides eluted either before or after the electroendoosmotic flow (EOF) marker, depending on the concentrat…
Determination of cow's milk and ripening time in nonbovine cheese by capillary electrophoresis of the ethanol-water protein fraction
2000
A novel method is reported for analyzing adulteration of goat and ewe cheeses with cow's milk: capillary zone electrophoresis (CZE) in isoelectric, acidic buffers (50 mM imino diacetic acid, IDA, pH = pI 2.3). The cheese samples were extracted with a 20:80 v/v ethanol-water mixture in presence of 3 M urea and 1% beta-mercaptoethanol for 1 h. After centrifugation and lipid extraction, the samples were dissolved in 50 mM IDA, 6 M urea and 0.5% hydroxyethyl cellulose and analyzed by CZE at 700 V/cm. A total of 18 characteristic peaks were resolved among the three types of cheeses and 18 variables were defined as their respective areas. There was excellent similarity among the electrophoretic p…
Determination of quinolone residues in chicken and fish by capillary electrophoresis-mass spectrometry
2006
A specific pressure-assisted CE-MS method is described for the analysis of five quinolone residues. MS using a single quadrupole is compared with multiple-stage MS using a quadrupole IT (QIT-MS(n)). The procedure involves a common sample preparation by SPE on disposable cartridges. The most suitable electrolyte is 60 mM (NH(4))(2)CO(3) at pH 9.2. Single quadrupole does not provide enough fragmentation to confirm identities according to the current legislation. However, QIT-MS(n) achieves selective fragmentation. Using this method, danofloxacin, enrofloxacin, flumequine, ofloxacin, and pipemidic acid are analyzed in fortified samples of chicken and fish. Recoveries at levels of 50 ng/g were …
Comparative study of capillary electroendosmotic chromatography and electrically assisted gradient nano-liquid chromatography for the separation of p…
2000
Capillary electroendoendosmotic chromatography (CEC), being a hybrid of high-performance liquid chromatography (HPLC) and capillary electrophoresis, offers considerable changes to enhance column efficiency, speed of analysis and additional selectivity as compared to the parent methods. The analytes are driven by the electroendosmotic flow (EOF) and separated by surface-solute interactions as well as by differences in electromigration. In this paper on the separation of peptides on C18 reversed-phase and mixed-mode (sulphonic acid-n-alkyl) packings in CEC and electrically assisted reversed-phase gradient nano-LC are investigated. It is shown that mixed mode packings generate a higher EOF tha…
Performance of a series of novel N-substituted acrylamides in capillary electrophoresis of DNA fragments
1996
DNA separations by capillary electrophoresis in viscous solutions of novel polymers, made with Ω-hydroxyl, N-substituted acrylamides (notably N-acryloyl amino propanol, AAP and N-acryloyl amino butanol, AAB) are evaluated. Whereas in standard poly(acrylamide), at 6% concentration, the theoretical plate number (N) does not exceed 500 000, in 6% poly(AAP) N reaches 922 000 and in 6% poly(AAB) N values as high as 1 200 000 are obtained. Also, copolymers of AAP and AAB give N values in excess of 1 million plates. The two novel monomers (AAP and AAB) remain extremely stable during alkaline hydrolysis and display very good hydrophilicity, while being devoid of the noxious habit of auto-polymeriza…
Determination of alternative and conventional chelating agents as copper(II) complexes by capillary zone electrophoresis—The first use of didecyldime…
2006
Abstract A capillary zone electrophoresis (CZE) method for analyzing 11 chelating agents [β-alaninediacetic acid (β-ADA), trans-1,2-diaminocyclohexane- N , N , N ′, N ′-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N -(2-hydroxyethyl)ethylenediamine- N , N ′, N ′-triacetic acid (HEDTA), N -(2-hydroxyethyl)iminodiacetic acid (HEIDA), iminodiacetic acid (IDA), methylglycinediacetic acid (MGDA), nitrilotriacetic acid (NTA), 1,3-diaminopropane- N , N , N ′, N ′-tetraacetic acid (PDTA) and triethylenetetraaminehexaacetic acid (TTHA)] as negatively charged copper(II) complexes has been established. Both conventional and alternative che…