A sensitive and selective chemiluminescence (CL) method was developed for the determination of cysteine. This method is based on that the weak CL of cysteine oxidized with cerium (IV) can be greatly enhanced by quinine, and the total cysteine in human serum can be detected through simply diluting with water, showing a simpler analytical characteristic.
Li Hua NIEHui Min MAMei Hong SUMing SUNXiao Hua LI
Using microbore HPLC and electrochemical detection, A microdialysis HPLC assay system was built. After investigating the linear range, detection limit and reproducibility, this method was used to measure the concentrations of DA and monoamine metabolites in striatal microdialysate with 5 min temporal resolution. The detection limit is less than 5 nmol/L. According to the statistical analysis, the result is stable and accurate. It is very helpful to the physiological, pathological and pharmacological research.
The microchip capillary electrophoresis devices were fabricated by using poly(methyl methacrylate)(PMMA) plastic material via an injection-molding process. The molded devices were enclosed by utilizing a mixed organic solvent to another PMMA film. The channel structure was very well defined and the molded channel surfaces were very smooth. The transmissivity was in the range from 91% to 93%(at the wavelength of 400—1 000 nm). In comparison to glass microchannels, the electroosmotic flow(EOF) in native PMMA channels was low. DNA marker separation was demonstrated in these PMMA devices with a high-resolution separation of double-stranded DNA fragments, chip-to-chip and the run-to-run reproducibility was good, and the relative standard deviation(%) values were below 2.2% for run-to-run data and 2.3% for the chip-to-chip comparisons. The PCR amplification products and proteins were analyzed on the PMMA chips. Such devices lead to the production of low-cost, disposable chips suitable for a variety of separation applications, including DNA sizing, DNA sequencing, protein and medical analysis. The detection limits of Rhodamine 6G dye for the unmodified PMMA chip and the modified PMMA chips were 1.0×10 -10 and 6.67×10 -13 mol/L, respectively.
The interactions between granulocyte-colony stimulating factor (G-CSF) and dextran sulfate / κ-carrageenan oligosaccharide were studied by capillary zone electrophoresis. Dextran sulfate could strongly interact with G-CSF and the complex was detected. The binding constant and stoichiometry were determined to be 1.2×106 (mol/L)-1 and 3:1, respectively. However, the interaction between κ-carrageenan oligosaccharide and G-CSF was not found.
