RESUMO
Objective:To determine the equilibrium solubility and n-octanol/water partition coefficients (Papp)of cinnamon acid and cinnamaldehyde. Methods:The equilibrium solubility of cinnamon acid and cinnamaldehyde in different solutions was determined by HPLC,and their n-octanol/water partition coefficients were determined by a shaking flask method combined with HPLC-DAD. Results:When the pH of solution was 7.8,the equilibrium solubility of cinnamon acid was the largest,while that of cinnamaldehyde was the largest in pH 6.8 solution. The scopes of lgPappof cinnamon acid and cinnamaldehyde in different buffer solutions(pH 1.2-7.8) were -1.04-2.27 and 0.29-1.67, respectively, while those in n-octanol/water solvent were 0.85 and 1.26, respectively. Conclusion:The method is simple,accurate and fast to predicate the absorption of chemical components. In gastrointestinal physiological environment,cinnamaldehyde has good absorption, while cinnamon acid is with poor absorption in stomach and with better absorption in intestinal.
RESUMO
Abstract A novel luminol electrochemiluminescence strategy based on titanium dioxide/carbon nanotubes ( TiO2/CNTs) nanocomposites for detection of glucose was developed. First, the TiO2/CNTs nanocomposites were prepared by a sol-gel method and modified on the glassy carbon electrode. The electrochemiluminescence ( ECL) signal could be greatly enhanced when the electrode was established by the nanocomposites, which finally resulted in the increased sensitivity. Glucose oxidase calalyzed the oxidation of glucose to form H2 O2 , and the H2 O2 reacted with luminol to produce the ECL signal. Thus the above system was proved to be efficient for glucose detection. The modified electrode exhibited excellent ECL signals and a good linear range of 1. 0í10-7-5. 0í10-6 mol/L with a detection limit of 5. 2í10-8 mol/L towards glucose detection. This strategy was successfully demonstrated as a sensitive, rapid, simple and cost-effective method to detect glucose. Meanwhile, the TiO2/CNTs nanocomposites offered a novel material for the signal enhancement in electrochemiluminescence sensor.