Hybrid organic-inorganic phenyl monolithic column for capillary electrochromatography.

A novel hybrid organic-inorganic silica-based monolithic column possessing phenyl ligands for reversed-phase (RP) capillary electrochromatography (CEC) is described. The monolithic stationary phase was prepared by in situ co-condensation of tetraethoxysilane (TEOS) with phenyltriethoxysilane (PTES) via a two-step catalytic sol-gel procedure to introduce phenyl groups distributed throughout the silica matrix for chromatographic interaction. The hydrolysis and condensation reactions of precursors were chemically controlled through pH variation by adding hydrochloric acid and dodecylamine, respectively.

Analysis of flavonoids in leaves of Adinandra nitida by capillary electrochromatography on monolithic columns with stepwise gradient elution.

Extracts of Adinandra nitida leaves, known as Shiyacha in China, were analyzed by monolithic columns of capillary electrochromatography (CEC). To obtain good resolution within a short time, stepwise gradient elution of CEC was employed, and the effects of experimental parameters, such as the buffer, the gradient conditions, and the mode of injection were studied systematically. Under optimized conditions, analysis could be accomplished in 25 min on a monolithic rod of macroporous poly(butyl methacrylate-co-ethylene dimethacrylate).

[Application in capillary electrophoresis-based two-dimensional separation system].

An on-column, etched fused-silica porous junction interface was designed and fabricated, and an integrated two-dimensional separation platform involving on-line coupling of capillary isoelectric focusing (CIEF) with capillary electrophoresis (CE) was constructed by the interface. The primary advantages of this novel porous junction interface over previous designs are no dead volume, simplicity, ruggedness and convenience of column switching. This interface is particularly well suited for on-line coupling of CE-based multiple dimensional separation system.

On-line concentration of peptides and proteins with the hyphenation of polymer monolithic immobilized metal affinity chromatography and capillary electrophoresis.

An iminodiacetic acid (IDA)-type adsorbent is prepared at the one end of a capillary by covalently bonding IDA to the monolithic rods of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate). Cu(II) is later introduced to the support via the interaction with IDA. By this means, polymer monolithic immobilized metal affinity chromatography (IMAC) materials are prepared.

[Expression of tobacco SKP1 gene induced by oligochitosan].

Oligochitosan is an effective inductor for plant resistance. To understand the induced resistance mechanism, mRNA differential display was used to isolate genes from Nicotiana tabacum var. Samsun NN and four enhanced-expression gene fragments were obtained and were reamplified.

On-line concentration of proteins in pressurized capillary electrochromatography coupled with electrospray ionization-mass spectrometry.

Pressurized capillary electrochromatography (pCEC) and electrospray ionization-mass spectrometry (ESI-MS) have been hyphenated for protein analysis. Taken cytochrome c, lysozyme, and insulin as samples, the limits of detection (LODs) for absolute concentrations are 10(-11) mol (signal-to-noise ratio S/N = 3) with relative standard deviations (RSDs) of retention time and peak area, respectively, of less than 1.7% and 4.

[Micellar electrokinetic capillary chromatographic separation of amino acids derivatized with 2-(9-carbazole)-ethyl chloroformate as a pre-column labeling reagent].

2-(9-Carbazole)-ethyl chloroformate (CEOC) has been used for the pre-column derivatization of amino acids in micellar electrokinetic capillary chromatography (MEKC). Nine amino acid standards (Ser, Thr, Gly, Glu, Asp, Val, Ile, Leu, Phe) were labeled with CEOC and separated in a buffer system containing 20 mmol/L borate-30 mmol/L sodium lauryl sulfate (SDS) and 3% acetonitrile at pH 9.0 with an applied voltage of 18 kV and column temperature of 25 degrees C.

Protocol of capillary isoelectric focusing to separate extremely acidic and basic proteins.

A new set-up was constructed for capillary isoelectric focusing (CIEF) involving a sampling capillary as a bypass fixed to the separation capillary. Sample solutions were subjected to a previously established pH gradient from the sample capillary. Besides performing conventional CIEF, the separation of ampholytic compounds with isoelectric points (p/s) beyond the pH gradient was carried out on this system.

On-line combination of capillary isoelectric focusing and capillary non-gel sieving electrophoresis using a hollow-fiber membrane interface: a novel two-dimensional separation system for proteins.

A novel two-dimensional (2D) separation system for proteins was reported. In the system, a piece of dialysis hollow-fiber membrane was employed as the interface for on-line combination of capillary isoelectric focusing (CIEF) and capillary non-gel sieving electrophoresis (CNGSE). The system is similar equivalent to two-dimensional polyacrylamide gel electrophoresis (2D PAGE), by transferring the principal of 2D PAGE separation to the capillary format.

[Optimization of cDNA microarray fabrication].

To optimize and screen the most suitable target gene length,concentration and printing solution in cDNA microarray, housekeeping genes, such as beta actin and GAPDH, were selected as targets and hepatitis B virus gene as negative control. The RT-PCR primers that spanned at least one intron and whose products were at between 189 bp and 1078 bp were designed with primer premier 5.0, so did the hepatitis B virus gene PCR primer.

Mutations of mitochondrial 12S rRNA in gastric carcinoma and their significance.

Aim: To detect the variations of mitochondrial 12S rRNA in patients with gastric carcinoma, and to study their significance and the relationship between these variations and the genesis of gastric carcinoma.

Methods: PCR amplified mitochondrial 12S rRNA of 44 samples including 22 from gastric carcinoma tissues and 22 from adjacent normal tissues, was detected by direct DNA sequencing. Then laser capture microdissection technique (LCM) was used to separate the cancerous cells and dysplasia cells with specific mutations.

Pressurized electrochromatography coupled with electrospray ionization mass spectrometry for analysis of peptides and proteins.

Pressurized capillary electrochromatography (pCEC) was coupled with electrospray ionization mass spectrometry (ESI-MS) using a coaxial sheath liquid interface. It was used for separation and analysis of peptides and proteins. The effects of organic modifier and applied voltage on separation were investigated, and the effects of pH value of the mobile phase and the concentration of the electrolyte on ESI-MS signal were investigated.

An etched porous interface for on-line capillary electrophoresis-based two-dimensional separation system.

The construction and evaluation of an on-column etched fused-silica porous junction for on-line coupling of capillary isoelectric focusing (CIEF) with capillary zone electrophoresis (CZE) are described. Where two separation columns were integrated on a single piece of fused-silica capillary through the etched approximately 4 to 5-mm length porous junction along the capillary. The junction is easily prepared by etching a short section of the capillary wall with HF after removing the polyimide coating.

Hybrid organic-inorganic monolithic stationary phase for acidic compounds separation by capillary electrochromatography.

A novel type of organic-inorganic hybrid porous silica-based monolithic stationary phase for capillary electrochromatography (CEC) has been developed by sol-gel chemistry combined with supramolecular template-based approach in a simple and rapid manner. Both chromatographic interaction and electrophoretic migration contribute to the separation of acidic compounds by the monolithic column. Eight organic acids were separated rapidly with column efficiency up to 267,000 theoretical plates/m.

Influence of moderate Joule heating on electroosmotic flow velocity, retention, and efficiency in capillary electrochromatography.

The influence of Joule heating on electroosmotic flow velocity, the retention factor of neutral analytes, and separation efficiency in capillary electrochromatography was investigated theoretically and experimentally. A plot of electrical current against the applied electrical field strength was used to evaluate the Joule heating effect. When the mobile phase concentration of Tris buffer exceeded 5.

Repeatedly usable immobilized pH gradient in a monolithic capillary column.

Glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) were used to synthesize a monolithic capillary column containing reactive epoxy groups. Glutaraldehyde was introduced and linked to the monolith after a process of amination. An aqueous solution of commercial carrier ampholytes (CAs, Ampholine) was focused in such a polymer column.

Separation of acidic and basic compounds in capillary electrochromatography with polymethacrylate-based monolithic columns.

Methacrylate-based monolithic columns with electroosmotic flow (EOF) or very weak EOF are prepared by in situ copolymerization in the presence of a porogen in fused-silica capillaries pretreated with a bifunctional reagent. Satisfactory separations of acidic and basic compounds on the column with EOF at either low or high pH are achieved, respectively. With sulfonic groups as dissociation functionalities, sufficient EOF mobility still remains as high as 1.

On-line concentration of neutral and charged species in capillary electrochromatography with a methacrylate-based monolithic stationary phase.

A method involving self-concentration, on-column enrichment and field-amplified sample stacking for on-line concentration in capillary electrochromatography with a polymer monolithic column is presented. Since monolithic columns eliminate the frit fabrication and the problems associated with frits, the experimental conditions could be more flexibly adjusted to obtain higher concentration factor in comparison with conventional particulate packed columns. With self-concentration effect, the detection sensitivity of benzene and hexylbenzene is improved by a factor of 4 and 8, respectively.

A simple and robust set-up for on-column sample preconcentration--nano-liquid chromatography--electrospray ionization mass spectrometry for the analysis of N-acylhomoserine lactones.

A simple method for the simultaneous, rapid and sensitive determination of N-acylhomoserine lactone signaling molecules in bacterial isolates, without prior sample preconcentration and with minimal sample cleanup, is presented. The analysis relies on the combination of analyte preconcentration and separation on a single device: a relatively large sample volume (1-5 microL) is directly loaded onto a laboratory-made, miniaturized (75 microm i. d.

Two-dimensional capillary electrophoresis involving capillary isoelectric focusing and capillary zone electrophoresis.

Capillary isoelectric focusing (cIEF) and capillary zone electrophoresis (CZE) was on-line hyphenated by a dialysis interface to achieve a 2D capillary electrophoresis (CE) system. The system was used with just one high-voltage power supply and three electrodes (one cathode shared by the two dimensions). The focused zone in the first dimension (i.

Variations of mitochondrial D-loop region plus downstream gene 1 2S rRNA-tRNA(phe) and gastric carcinomas.

Aim: To explore the instabilities, polymorphisms and other variations of mitochondrial D-loop region and downstream gene 12S rRNA-tRNA(phe) in gastric cancers, and to study their relationship with gastric cancer.

Methods: Three adjacent regions (D-loop, tRNA(phe) and 12S rRNA) were detected for instabilities, polymorphisms and other variations via PCR amplification followed by direct DNA sequencing in 22 matched gastric cancerous tissues and para-cancerous normal tissues.

Results: PolyC or (CA) (n) instabilities were detected in 13/22(59.

Determination of 1-phenyl-3-methyl-5-pyrazolone-labeled carbohydrates by liquid chromatography and micellar electrokinetic chromatography.

In this paper, the method for the derivatization of carbohydrates with 1-phenyl-3-methyl-5-pyrazolone (PMP) was simplified. One-third of the derivatization time was saved. Five monosaccharide derivatives have been well separated by MEKC and HPLC under optimized conditions.

[Significance of hRad17 mRNA expression in human gastric cancer].

Objective: To study the relationship between hRad17 mRNA expression and clinicopathologic factors and lymph node metastasis of gastric cancer, and to assess the significance of predicting the extent of lymph node metastasis and prognosis.

Methods: hRad17 mRNA expression was examined in matched primary lesions, normal gastric mucosa and lymph node metastatic lesions among 52 gastric cancer patients by reverse transcription polymerase chain reaction (RT-PCR), polyacrylamide gel electrophoresis (PAGE) and silver stain with the relation between hRad17 mRNA expression and clinicopathologic factors analyzed. At the same time, hRad17 mRNA expressions in 5 gastric benign lesions and SGC7901 gastric carcinoma cell lines were also examined.