Biomedical subjects

Hongzhe Tian

Publications and source records attributed to Hongzhe Tian.

3 recordsLinked to original sources

PubMed2006

Multidimensional liquid chromatography system with an innovative solvent evaporation interface.

An orthogonal two-dimensional liquid chromatographic (2D-LC) system was developed by using a vacuum-evaporation loop-type valve interface. Normal-phase liquid chromatography (NPLC) with a bonded CN phase column was used as the first dimension, and reversed-phase liquid chromatography (RPLC) with a C(18) column was used as the second dimension. All the solvents in the loop of the interface were evaporated at 90 degrees C under vacuum conditions, leaving the analytes on the inner wall of the loop. The mobile phase of the second dimension dissolved the analytes in the loop and injected them onto the secondary column, allowing an on-line solvent exchange of a selected fraction from the first dimension to the second dimension. The chromatographic resolution of analytes on the two dimensions was maintained at their optimal condition. Sample loss due to evaporation in the interface was observed that depended on the boiling point of the compound. Separation of sixteen polycyclic aromatic hydrocarbon mixtures and a traditional Chinese medicine Angelica dahurica was demonstrated.

Angelica↗

PubMed2006

On-line preconcentration of protein in capillary electrophoresis with an end-column cellulose acetate-based porous membrane.

A simple on-line preconcentration method of protein for capillary electrophoresis (CE) using a cellulose acetate (CA)-coated porous membrane was proposed. CA membrane is fabricated at one of the ends of the column that allows the passage of buffer ions but excludes larger protein molecules. Protein sample is continuously electrokinetically loaded and trapped by the membrane. When injection is completed, the direction of the electric field is switched and the trapped proteins are then separated by conventional CE procedure. The results achieved showed that the preconcentration mechanism of this method was based on size-exclusion effect. Bovine serum albumin (BSA) was used for model protein sample, and signal enhancement of 550-fold with 15 min injection time was achieved.

Cellulose↗

PubMed2005

[Separation and identification of isoflavonoids in Pueraria lobata extracts and its preparations by reversed-phase capillary liquid chromatography coupled with electrospray ionization quadrupole time of flight mass spectrometry].

Isoflavonoids in Pueraria lobata extract and its preparations were separated and identified by reversed-phase capillary liquid chromatography (RP-CapLC) coupled with photodiode array (PDA) detector and negative electrospray ionization quadrupole time of flight (Q-TOF) mass spectrometry. The separation was performed on a 150 mm x 0. 32 mm i. d. , 5 microm C18 capillary column, using mobile phase of 0.1% aqueous trifluoroacetic acid solution and acetonitrile containing 0.1% trifluoroacetic acid under gradient elution. The product ion spectra of the deprotonated ions allowed for the identification of puerarin, daidzin and daidzein in the sample. Puerarin was found to be the most abundant component in the extract (about 13%, mass fraction) and its preparations (19.28 - 24.34 mg per tablet). The structures of trace amount of unknown isoflavonoids were deduced based on the spectra of known compounds. They were proposed to be 3'-methoxypuerarin and 3'-methoxydaidzin.

Chromatography, High Pressure Liquid↗