To study the chemical constituents of Stenoloma chusana.The compounds were isolated and purified by recrystallization and various chromatographic techniques.The structures were elucidated by chemical evidence and spec...To study the chemical constituents of Stenoloma chusana.The compounds were isolated and purified by recrystallization and various chromatographic techniques.The structures were elucidated by chemical evidence and spectroscopi methods.five compounds were obtained and identified as(1)hexacosanoic acid,(2)3-hydroxy-heptacosanol,(3)phthalic acid bis-(2-ethylhexyl)ester,(4)β-sitosterol,(5)daucosterol.The five compounds were isolated from this genus for the first time.展开更多
Based on the principle of the reaction of NO2-with I-and formation of I2 in HCl solution,and the chemiluminescence(CL) reaction between luminol and I2 in an alkaline medium.A fairly sensitive,simple and rapid flow-inj...Based on the principle of the reaction of NO2-with I-and formation of I2 in HCl solution,and the chemiluminescence(CL) reaction between luminol and I2 in an alkaline medium.A fairly sensitive,simple and rapid flow-injection analysis-chemiluminescence method for the determina-tion of trace nitrite with the luminal-I——NO2-coupling luminescence system has been developed.Experiment conditions of flow-injection analysis are optimized.When satisfying the condition that Luminol as 4.0×10-4 mol/L,0.7 % KI,0.04 mol/L HCl;the length of reaction coil as 250 cm;the velocity of primary pump as 10r/min;the velocity of ancillary pump as 20 r/min.Under optimum conditions,the detection limit for NO2-is 0.5 μg/L,the linear range of the determination is 1.0～100.0 μg/L.The method can be applied to determination of trace NO2-in environmental water and green stuff with satisfactory results.展开更多
化学需氧量(COD)是工业废水和环境水质监测中重要的项目之一。文章采用微波消解—分光光度法测定工业废水中COD,并对此方法进行条件实验。确定最佳消解条件为:催化剂为0.05 mol/L硫酸镍-硫酸溶液,催化剂用量为3 m L,消解时间为4 min,于3...化学需氧量(COD)是工业废水和环境水质监测中重要的项目之一。文章采用微波消解—分光光度法测定工业废水中COD,并对此方法进行条件实验。确定最佳消解条件为:催化剂为0.05 mol/L硫酸镍-硫酸溶液,催化剂用量为3 m L,消解时间为4 min,于350nm波长处测定过量Cr(Ⅵ)的浓度。结果表明:吸光度与COD值在10~100 mg/L范围内呈良好的线性关系。实际水样测定结果相对偏差小于2%,平均加标回收率达到98.02%,该方法具有消解时间短、准确度高、操作简单等特点。展开更多
文摘To study the chemical constituents of Stenoloma chusana.The compounds were isolated and purified by recrystallization and various chromatographic techniques.The structures were elucidated by chemical evidence and spectroscopi methods.five compounds were obtained and identified as(1)hexacosanoic acid,(2)3-hydroxy-heptacosanol,(3)phthalic acid bis-(2-ethylhexyl)ester,(4)β-sitosterol,(5)daucosterol.The five compounds were isolated from this genus for the first time.
文摘Based on the principle of the reaction of NO2-with I-and formation of I2 in HCl solution,and the chemiluminescence(CL) reaction between luminol and I2 in an alkaline medium.A fairly sensitive,simple and rapid flow-injection analysis-chemiluminescence method for the determina-tion of trace nitrite with the luminal-I——NO2-coupling luminescence system has been developed.Experiment conditions of flow-injection analysis are optimized.When satisfying the condition that Luminol as 4.0×10-4 mol/L,0.7 % KI,0.04 mol/L HCl;the length of reaction coil as 250 cm;the velocity of primary pump as 10r/min;the velocity of ancillary pump as 20 r/min.Under optimum conditions,the detection limit for NO2-is 0.5 μg/L,the linear range of the determination is 1.0～100.0 μg/L.The method can be applied to determination of trace NO2-in environmental water and green stuff with satisfactory results.
