OBJECTIVE: To establish a HPLC method for the determination of content of entecavir and its related substances. METHODS: The HPLC condition was consisted of a Luna C18 column with a column temperature at 25 ℃, using gradient eluate method, the mobile phase was acetonitrile,with a flow rate of 1.0 mL?min-1 and detection at 254 nm. RESULTS: The calibrated linear curve of entecavir was within 0.033 45～0.167 2 mg?mL-1(r=0.999 98). The average recovery was 100.09%,RSD=0.20%, The content of related substance was 0.54%～1.48%. CONCLUSION: This accurate and reliable HPLC method is applicable for the quality control of entecavir and its related substances.

The technology of Magnetic Resonance Spectroscopy(MRS) is a newly-developed mean for analyzing some specific nucleus and their compounds making use of the principles of magnetic resonance and the effects of chemical shift. Currently, among MRS applications, proton magnetic resonance spectroscopy (1HMRS) is the most widely applied one developed from single voxel to three-dimensional multi-voxel scanning technique. It provides a lot of important information for clinical studies. This article mainly reviews the methods for absolute quantification measurement of brain metabolites using multi-voxel MRS.

OBJECTIVE:To establish an RP-HPLC method for content determination of s-omeprazole sodium and its related substances.METHODS:The separation of s-omeprazole sodium and the related substances was carried out on a Phenomenex Luna C18 column,the mobile phase consisted of methanol-0.033 mol?L-1 ammonium dihydrogen phosphate-triethylamine (58∶41.8∶0.2,adjusted to pH 7.0 by phosphate acid).The detection wavelength was 302 nm,the flow rate was 1.0 mL?min-1,the column temperature was 25 ℃,and the sample size was 20 ?L.RESULTS:The linear range of omeprazole sodium was 10～500 mg?L-1 (r=0.999 7).The average recovery rate was 100.27% (RSD=0.74%).The average content of the related substances in samples was 0.42%.CONCLUSION:This method is simple,accurate,specific and applicable for content determination of s-omeprazole sodium and its related substances.

OBJECTIVE:To establishment the method for the determination of content of vitamin A palmitate(VAP) and its related substances by HPLC. METHODS:The HPLC conditions were consisted of Phenomenex Luna C18 column with a mobile phase of a mixture of acetonitrile-isopropanol (90∶10) ,the detection wavelength of 328 nm,the column temperature of 30 ℃ and the flow rate of 1.0 mL?min-1. RESULTS:VAP was completely separated from impurities,the linearity range was 90～400 mg?L-1(r=0.999 2). The average recovery rate was 99.60% (RSD=1.32%). The average content of the related substances were lower than 2.53% . CONCLUSION: This accurate and reliable HPLC method is applicable for the quality control of VAP.

Irritable bowel syndrome (IBS) is characterized by abdominal pain associated with changes in defecation frequency and blood folate level. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. High-FODMAP diet could elicit or exacerbate IBS-associated bowel symptoms, which is inadequately recognized among gastroenterologists in China. Here we report an IBS case, focusing on the association between high-FODMAP diet and bowel symptoms and the intervention of low-FODMAP diet.