从万寿菊花中提取叶黄素的工艺研究

研究了从万寿菊花提取叶黄素的工艺条件,包括溶剂的选择、提取次数、时间以及料液比,并对其传统的工艺流程进行了改进,结果发现将万寿菊花、四氢呋喃、乙醇、水和KOH在室温下混合,同时进行萃取和皂化处理的工艺流程最佳。按该工艺生产的叶黄素的纯度在97.6%以上。     

7 羟基 4 甲基香豆素钠盐的合成及结构表征

以7-羟基-4-甲基香豆素与氢氧化钠为原料合成标题化合物,并进行重结晶溶剂筛选及纯化精制,采用TLC、UV、IR、1H NMR、13C NMR和MS进行结构表征。结果表明,7-羟基-4-甲基香豆素与氢氧化钠较易形成钠盐,在水-丙酮中易形成结晶,用体积分数为92%丙酮溶液重结晶可得到淡黄色针状晶体,产率75%。该方法操作简单,成本低廉,对规模化生产具有重要指导意义。     

正交试验优化重结晶法纯化芝麻素的工艺及HPLC成分分析

[目的]采用重结晶法纯化高纯度的芝麻素,得到最优的重结晶纯化条件,并分析其含量纯度.[方法]以芝麻粕为实验材料,醇提、大孔树脂吸附、乙醇结晶、丙酮-异丙醇重结晶方法纯化芝麻素.HPLC法测定芝麻素含量.应用重结晶纯化技术,采用单因素和正交试验优化方法,选取芝麻素初结晶料液比、热溶解温度、下降温度三个单因素作为考察指标,优化芝麻素重结晶条件.[结果]通过单因素和正交试验结果分析得到,最优芝麻素重结晶条件为:料液比1:10,热溶解温度45℃,结晶温度25 ℃,在此条件下重结晶样品经HPLC分析芝麻素含量达到95.26％.[结论]采用重结晶法纯化技术,通过单因素和正交试验法优化实验,并经HPLC含量分析,得到了高纯度的芝麻素结晶.     

Effect of temperature and rhizosphere processes on pedogenic carbonate recrystallization: Relevance for paleoenvironmental applications

In soils of arid and semiarid climates, dissolution of primary (lithogenic) carbonate and recrystallization with CO₂ from soil air leads to precipitation of pedogenic carbonates and formation of calcic horizons. Thus, their carbon isotope composition represents the conditions prevailing during their formation. However, the widespread use of the isotopic signature (δ¹³C, δ¹⁸O, Δ¹⁴C) of pedogenic carbonates for reconstruction of local paleovegetation, paleoprecipitation and other environmental conditions lacks knowledge of the time frame of pedogenic carbonate formation, which depends on climatic factors. We hypothesized that temperature-dependent biotic processes like plant growth and root and rhizomicrobial respiration have stronger influence on soil CaCO₃ recrystallization than abiotic temperature-dependent solubility of CO₂ and CaCO₃.To assess the effect of temperature on initial CaCO₃ recrystallization rates, loess with primary CaCO₃ was exposed to ¹⁴CO₂ from root and rhizomicrobial respiration of plants labeled in ¹⁴CO₂ atmosphere at 10, 20 or 30 °C. ¹⁴C recovered in recrystallized CaCO₃ was quantified to calculate amounts of secondary CaCO₃ and corresponding recrystallization rates, which were in the range of 10⁻⁶-10⁻⁴ day⁻¹, meaning that 10⁻⁴-10⁻²% of total loess CaCO₃ were recrystallized per day. Increasing rates with increasing temperature showed the major role of biological activities like enhanced water uptake by roots and respiration. The abiotic effect of lower solubility of CO₂ in water by increasing temperature was completely overcompensated by biotic processes. Based on initial recrystallization rates, periods necessary for complete recrystallization were estimated for different temperatures, presuming that CaCO₃ recrystallization in soil takes place mainly during the growing season. Taking into account the shortening effect of increasing temperature on the length of growing season, the contrast between low and high temperature was diminished, yielding recrystallization periods of 5740 years, 4330 years and 1060 years at 10, 20 and 30 °C, respectively. In summary, increasing CaCO₃ recrystallization rates with increasing temperature demonstrated the important role of vegetation for pedogenic CaCO₃ formation and the predominantly biotic effects of growing season temperature.Considering the long periods of pedogenic carbonate formation lasting to some millennia, we conclude that methodological resolution of paleoenvironmental studies based on isotope composition of pedogenic carbonates is limited not by instrumental precision but by the time frame of pedogenic carbonate formation and hence cannot be better than thousands of years.