[Progress in quantitative methods based on liquid chromatography-mass spectrometry for drug metabolizing enzymes in human liver microsomes].

Cytochrome P450 (CYP) enzymes and uridine 5-diphospho-glucuronosyltransferase (UGT) enzymes are critical enzymes for drug metabolism. Both chemical drugs and traditional Chinese medicines are converted to more readily excreted compounds by drug metabolizing enzymes in human livers. Because of the disparate expression of CYP and UGT enzymes among different individuals, accurate quantification of these enzymes is essential for drug pharmacology, drug-drug interactions and drug clinical applications. The research progress in quantitative methods based on liquid chromatography-mass spectrometry for drug metabolizing enzymes in human liver microsomes in the recent decade is reviewed.

[A simple preparation method of an electric heating apparatus for heating capillary chromatographic columns and its application in liquid chromatography-mass spectrometry system].

For deep coverage of proteome, especially in performing qualitative identification and quantitative analysis of low-abundance proteins, the most commonly used method is the application of a longer capillary chromatographic column or a capillary column packed with smaller particle sizes. However, this causes another problem, the very high back pressure which results in liquid leaks in some connection parts in a liquid chromatograph. To solve this problem, an electric heating apparatus was developed to raise the temperature of a capillary column for reducing its back pressure, which was further applied in a capillary high performance liquid chromatography-tandem mass spectrometry system (cHPLC-MS/MS), and evaluated in the terms of chromatographic column back pressure and chromatographic column efficiency using bovine serum albumin (BSA) tryptic digests and yeast tryptic digests, separately. The results showed that at the optimum current, our electric heating apparatus could reduce the column pressure of a capillary column packed with 3 µm packing materials by at least 50% during the separation of BSA tryptic digestion and yeast tryptic digestion, compared with that without electric heating. The column efficiency was also increased slightly. This suggested that the electric heating apparatus can significantly reduce the column pressure, which provides an efficient way to use capillary chromatographic columns packed with smaller sizes of particles at a lower pressure.

[A novel multiple-channel apparatus for packing capillary chromatographic column and its application].

A novel multiple-channel apparatus for packing capillary chromatographic column was designed and manufactured for packing six capillary chromatographic columns with close column efficiency at the same time. Briefly, it consists of a magnetic stirrer, a liquid chromatographic pump and a multiple-channel can. The reagents used for preparing ODS (C18) slurry and stirring condition of the magnetic stirrer were optimized in the study. Two batches of capillary chromatographic columns were packed under the optimum condition, and these packed capillary chromatographic columns were evaluated in the terms of peak capacity, sequence coverage, retention times of three peptide ions and column pressure using the tryptic digest of a bovine serum albumin (BSA) and detected by LC-MS in electrospray ionization (ESI) mode. The experimental results showed that the six capillary chromatographic columns packed at the same time had close column efficiencies, however, the column efficiencies of twelve capillary chromatographic columns packed at two times were significantly different. In addition, there was no significant column efficiency difference when packing one or six capillary chromatographic columns at the same time. The multiple-channel apparatus designed by us is simple, time-saving, and can be applied to pack capillary chromatographic columns with similar column efficiencies, thus it is of evident advantage over traditional one-channel apparatus.