A valve-free continuous flow method and instrument were established,with only a multi-channel pump for delivering the sample and reagent,and without any injection or solenoid valves and sample loop for selecting and adding the sample or reagent.Nitrate was reduced to nitrite with Cu-Cd reductant column,and then detected with spectrophotometric detector.The proposed method was suitable for determination of nitrate at normal level in most of estuary and coastal seawaters.With the optimum parameters,the linear range and detection limit were 5-180 μmol/L and 0.27 μmol/L,respectively.The samples of 10 and 80 μmol/L nitrate were continually measured for 11 times,and the relative standard deviations were 1.4％ and 1.3％,respectively.The recovery of real samples at different salinity ranged between 99.4％ and 106.1％.There was no significant difference in the analytical results between the proposed method and the flow injection analysis (FIA).In comparison with FIA,the method and instrument were less cost and easy to operate,and was suitable to be applied in general laboratories and field for continuous monitoring.The method was successfully used to measure the nitrate in seawater samples in Xiamen's Western Harbor and monitor nitrate in Jiulongjiang estuary.

Present study was focused on the chemical constituents of the stems and leaves of Salvia yunnanensis C . H. Wright and their anti-angiogeneic activities. The compounds were isolated by column chromatography over silica gel and Sephadex LH-20, and other isolation techniques. Their structures were elucidated on the basis of spectral analysis and chemical evidences. Their anti-angiogeneic activities were evaluated by the chicken chorioallantoic membrane (CAM) neovascularisation model. Seven compounds were separated and identified as ( + ) -spathulenol( 1), 5,7,4'-trihydroxyflavanone(2) , beta-amyrin(3), 3 beta-hydroxy-12-ursene(4), 2alpha,3 beta-dihydroxyursa-12-en-28-oic acid(5), ursolic acid (6) and 3-oxo-12-ursen-28-oic acid (7). Compounds 1, 2, 5 and 6 were obtained from this plant for the first time. Compounds 5 (an oleanane compound) and 6 (an ursane compound) could inhibit angiogenesis significantly in a dose-dependent manner.
Angiogenesis Inhibitors ; chemistry ; pharmacology ; Animals ; Chorioallantoic Membrane ; drug effects ; metabolism ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; Plant Leaves ; chemistry ; Plant Stems ; chemistry ; Salvia ; chemistry