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Separation Capillary (separation + capillary)

Distribution by Scientific Domains

Chemistry	40%

Selected Abstracts

Sequencing of real-world samples using a microfabricated hybrid device having unconstrained straight separation channels

ELECTROPHORESIS, Issue 21 2003
Shaorong Liu
Abstract We describe a microfabricated hybrid device that consists of a microfabricated chip containing multiple twin-T injectors attached to an array of capillaries that serve as the separation channels. A new fabrication process was employed to create two differently sized round channels in a chip. Twin-T injectors were formed by the smaller round channels that match the bore of the separation capillaries and separation capillaries were incorporated to the injectors through the larger round channels that match the outer diameter of the capillaries. This allows for a minimum dead volume and provides a robust chip/capillary interface. This hybrid design takes full advantage, such as sample stacking and purification and uniform signal intensity profile, of the unique chip injection scheme for DNA sequencing while employing long straight capillaries for the separations. In essence, the separation channel length is optimized for both speed and resolution since it is unconstrained by chip size. To demonstrate the reliability and practicality of this hybrid device, we sequenced over 1000 real-world samples from Human Chromosome 5 and Ciona intestinalis, prepared at Joint Genome Institute. We achieved average Phred20 read of 675 bases in about 70 min with a success rate of 91%. For the similar type of samples on MegaBACE 1000, the average Phred20 read is about 550,600 bases in 120 min separation time with a success rate of about 80,90%. [source]

Determination of thyreostatics in animal feeds by CE with electrochemical detector

ELECTROPHORESIS, Issue 19 2009
Dexian Kong
Abstract A simple, rapid, reproducible and sensitive method based on CE with electrochemical detector was developed for the simultaneous determination of five thyreostatics including 2-thiouracil (TU), 6-methyl-2-thiouracil (MTU), 6-propyl-2-thiouracil (PTU), 6-phenyl-2-thiouracil (PhTU) and methimazole (TAP) in animal feeds. A home-made wall-jet electrochemical detector with a 300,,m diameter platinum-disk-working electrode was equipped at the end of separation capillary and used to detect oxidation currents of these thyreostatics. Under the optimum experimental conditions, TU, MTU, PTU, PhTU and TAP could be well separated within 15,min at the separation voltage of 16,kV in 20,mmol/L sodium borate buffer (pH 9.2). The detection limits (S/N=3) of the five thyreostatics in animal feeds were found to be 7.6,,g/kg for TAP, 25,,g/kg for PTU, 15,,g/kg for PhTU, 18,,g/kg for TU and 20,,g/kg for MTU by the developed CE with electrochemical detector method coupled with solid-phase extraction sample pretreatment technique. [source]

A microfabricated hybrid device for DNA sequencing

ELECTROPHORESIS, Issue 21 2003
Shaorong LiuArticle first published online: 6 NOV 200
Abstract We have created a hybrid device of a microfabricated round-channel twin-T injector incorporated with a separation capillary in order to extend the straight separation distance for high speed and long readlength DNA sequencing. Semicircular grooves on glass wafers are obtained using a photomask with a narrow line-width and a standard isotropic photolithographic etching process. Round channels are made when two etched wafers are face-to-face aligned and bonded. A two-mask fabrication process has been developed to make channels of two different diameters. The twin-T injector is formed by the smaller channels whose diameter matches the bore of the separation capillary, and the "usual" separation channel, now called the connection channel, is formed by the larger ones whose diameter matches the outer diameter of the separation capillary. The separation capillary is inserted through the connection channel all the way to the twin-T injector to allow the capillary bore flush with the twin-T injector channels. The total dead-volume of the connection is estimated to be , 5 pL. To demonstrate the efficiency of this hybrid device, we have performed four-color DNA sequencing on it. Using a 200 ,m twin-T injector coupled with a separation capillary of 20 cm effective separation distance, we have obtained readlengths of 800 plus bases at an accuracy of 98.5% in 56 min, compared to about 650 bases in 100 min on a conventional 40 cm long capillary sequencing machine under similar conditions. At an increased separation field strength and using a diluted sieving matrix, the separation time has been reduced to 20 min with a readlength of 700 bases at 98.5% base-calling accuracy. [source]

Capillary electrophoretic chiral separation of Cinchona alkaloids using a cyclodextrin selector

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 6-7 2008
Dimitrios Tsimachidis
Abstract A new capillary electrophoretic method for the chiral separation of four major Cinchona alkaloids (quinine/quinidine and cinchonine/cinchonidine) was developed using heptakis-(2,6-di- O -methyl)-,-cyclodextrin as the chiral selector. The inner walls of the separation capillary were modified with a thin polyacrylamide layer, which substantially reduced the electroosmotic flow and improved the chiral resolution and the reproducibility of the migration time of the analytes. Various operation parameters were optimised, including the pH, the capillary temperature, the concentration of the background electrolyte, and the concentration of the chiral selector. Baseline separation of the two diastereomer pairs was achieved in 12 minutes in ammonium acetate background electrolyte pH 5.0 with addition of cyclodextrin in a concentration of 3 mM or higher. [source]

Chemiluminescence determination of pharmacologically active compounds by capillary electrophoresis

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2005
Suqin Han
Abstract A simple and rapid capillary electrophoresis with direct chemiluminescence method has been developed for the determination of five natural pharmacologically active compounds including rutin, protocatechuic aldehyde, chlorogenic acid, luteolin and protocatechuic acid. The luminol as a component of the separation electrolyte buffer was introduced at the head of the separation capillary. The separation of five compounds was carried out in a fused-silica capillary with 15.0 mmol/L tetraborate, 1.0 mmol/L SDS and 0.42 mmol/L luminol (pH 8.5). The analytes was determined by enhancing the chemiluminescence of luminol with 0.13 mmol/L K3Fe(CN)6 in 0.05 mol/L NaOH, which was introduced at the post-column stage. The voltage applied was 16 kV. Under the optimum conditions, the analytes were separated within 10 min. The excellent linearity was obtained over two to three orders of magnitude with a detection limit (signal:noise = 3) of 0.012,0.055 µmol/L for all five analytes. The method was successfully used in the analysis of pharmaceutical and biological samples, and the assay results were satisfactory. Copyright © 2005 John Wiley & Sons, Ltd. [source]