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Capillary Electrophoretic Separation (capillary + electrophoretic_separation)
Selected AbstractsCapillary electrophoretic separation of biologically active amines and acids using nanoparticle-coated capillariesELECTROPHORESIS, Issue 9 2008Yu-Fen Huang Abstract This manuscript describes dynamic coating of capillaries with poly(L -lysine) (PLL) and silica nanoparticles (SiO2 NPs) and use of the as-prepared capillaries for the separation of biogenic amines and acids by CE in conjunction with LIF detection. The directions of EOF are controlled by varying the outmost layer of the capillaries with PLL and SiO2 NPs, respectively. Over the pH range 3.0,5.0, the (PLL,SiO2NP)n,PLL capillaries have an EOF toward the anodic end and are more suitable for the separation of acids with respect to speed, while the (PLL,SiO2NP)n capillaries have an EOF toward the cathodic end and are more suitable for the separation of biogenic amines regarding speed and sensitivity. The separations of standard solutions containing five amines and two acids by CE with LIF detection using (PLL,SiO2NP)2,PLL and (PLL,SiO2NP)3 capillaries were accomplished within 10 and 7,min, providing plate numbers of 3.8 and 5.0×104,plates/m for 5-hydroxytryptamine (5-HT), respectively. The LODs for 5-HT and 5-hydroxyindole-3-acetic acid (5-HIAA) are 32 and 2,nM and 0.2 and 1.5,nM when using the (PLL,SiO2NP)2,PLL and (PLL,SiO2NP)3 capillaries, respectively. Identification and quantification of 5-HIAA, homovanillic acid, and DL -vanillomandelic acid in urine samples from a male before and after drinking green tea were tested to validate practicality of the present approach. The results show that the (PLL,SiO2NP)2,PLL capillary provides greater resolving power, while the (PLL,SiO2NP)3 capillary provides better sensitivity, higher efficiency, and longer durability for the separation of the amines and acids. [source] Capillary electrophoretic separation and fractionation of hydrophobic peptides onto a pre-structured matrix assisted laser desorption/ionization target for mass spectrometric analysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2006Johan Jacksén Abstract A CE separation of hydrophobic peptides followed by fractionation onto a prestructured MALDI target and off-line MS analysis was performed. An improved and partially automated manufacturing procedure of the previously described MALDI target is presented. This target is structurally coated with silicone and especially developed for hydrophobic peptides and proteins. Here, the target plate was designed specifically for the CE fraction collection. Different solvents were evaluated to meet the requirements of peptide solubility and compatibility to both the CE and MALDI methods and to the fractionation procedure. CE-MALDI-MS analysis of nine highly hydrophobic peptides from cyanogen bromide-digested bacteriorhodopsin is demonstrated. [source] The Dependence of the Sensitivity and Reliability of Contactless Conductivity Detection on the Wall Thickness of Electrophoretic Fused-Silica CapillariesELECTROANALYSIS, Issue 3-5 2009Petr T Abstract A contactless conductivity detector (C4D) performance has been tested on a simple capillary electrophoretic separation in a standard fused-silica capillary with an external diameter of 360,,m and in a thin-walled capillary (an external diameter of 150,,m); the internal diameters of the two capillaries were identical, equal to 75,,m. Potassium and sodium ions have been separated in a morpholinoethanesulfonic acid/histidine background electrolyte (MES/His), over a wide range of its concentrations (0,100,mM). At low MES/His concentrations, the C4D response, obtained from the height of the potassium peak, is by 100 to 200 per cent higher for the thin-walled capillary and the calibration dependences are linear, in contrast to the thick-walled capillary. These differences between the two capillaries decrease with increasing MES/His concentration, the C4D response in the thin-walled capillary is then higher by mere 20 per cent and the calibration dependences are linear in both the capillaries. The highest sensitivities have been obtained at a MES/His concentration of 50,mM, with LOD values for potassium ion of 2.0 and 2.6,,M, in the thin- and thick-walled capillaries, respectively. The signal-to-noise ratios and the plate counts are generally similar for the two capillaries. It follows from the results that special thin-walled capillaries can be advantageous when background electrolytes with very low conductivities must be employed. [source] Electrokinetic-driven microfluidic system in poly(dimethylsiloxane) for mass spectrometry detection integrating sample injection, capillary electrophoresis, and electrospray emitter on-chipELECTROPHORESIS, Issue 24 2005Sara Thorslund Abstract A novel microsystem device in poly(dimethylsiloxane) (PDMS) for MS detection is presented. The microchip integrates sample injection, capillary electrophoretic separation, and electrospray emitter in a single substrate, and all modules are fabricated in the PDMS bulk material. The injection and separation flow is driven electrokinetically and the total amount of external equipment needed consists of a three-channel high-voltage power supply. The instant switching between sample injection and separation is performed through a series of low-cost relays, limiting the separation field strength to a maximum of 270,V/cm. We show that this set-up is sufficient to accomplish electrospray MS analysis and, to a moderate extent, microchip separation of standard peptides. A new method of instant in-channel oxidation makes it possible to overcome the problem of irreversibly bonded PDMS channels that have recovered their hydrophobic properties over time. The fast method turns the channel surfaces hydrophilic and less prone to nonspecific analyte adsorption, yielding better separation efficiencies and higher apparent peptide mobilities. [source] Nonaqueous capillary electrophoretic separation of polyphenolic compounds in wine using coated capillaries at high pH in methanolELECTROPHORESIS, Issue 24 2003Zuzana Demianová Abstract Nonaqueous capillary electrophoretic separation of a group of flavonoids (quercetin, myricetin, catechin, epicatechin) and resveratrol in wine was investigated in methanol at high pH. Malonate background electrolyte (pH* 13.5, ionic strength I = 14.2 mmol/L) provided highly repeatable separations of the analytes. Tests of untreated and coated (poly(glycidylmethacrylate- co - N -vinylpyrrolidone)) capillaries showed the analysis to be faster (6.5 min vs. 25 min) and the repeatability better in the coated capillaries. The coating procedure was simple and highly repeatable and the coating was stable during 40,45 runs. Determination of the last migrating peaks (epicatechin, resveratrol and catechin) was achieved merely by evaporating the wine samples and reconstituting the residue in methanol. For determination of the first migrating peaks (quercetin and myricetin) the samples were submitted to solid-phase extraction in C8 cartridges. [source] Indirect laser-induced fluorescence detection for capillary electrophoresis using a frequency-doubled diode laserELECTROPHORESIS, Issue 3 2003Natalia Ragozina Abstract A blue (452 nm) frequency-doubled diode laser with a quasi-cw optical output power of 10 ,W is used for indirect laser-induced fluorescence detection in combination with the capillary electrophoretic separation of inorganic anions. As fluorescing probe ion the anion of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) was selected having an absorption maximum of 454 nm in alkaline medium. Employing a capillary coated with linear acrylamide, baseline separation of eight inorganic anions was possible within 5 min. With a separation buffer containing 50 ,molˇL -1 HPTS and 10 mmolˇL -1 lysine the limits of detection for sulfate, nitrite, nitrate, azide, thiocyanate, and chlorate were between 0.9 and 4.7 ,molˇL -1. Separation of chloride and sulfate was achieved by adding 0.25 mmolˇL -1 calcium hydroxide to the separation buffer. Inorganic anions in several mineral and tap water samples have been determined with the technique developed and results are compared to data obtained by ion chromatography in combination with conductivity detection after conductivity suppression. [source] | ||||||||||