1:The purification of chemicals is one of the most important jobs for research chemist.化学物质的提纯是化学家研究的最重要的一个工作之一。
2:Perhaps the most common purification technique in our organic laboratory is column chromatography. 也许在我们的有机实验室最常用的净化技术是柱色谱法。
3:This technique takes the manager of the different polarity of different compounds, just separate mixtures, frequently on the gram scale.该技术以不同的化合物的极性不同,只是分离混合物,通常在克级。
4:Technically, column chromatography can be challenging. But with a little practice, you can be able to separate mixture compounds consistently and successfully.从技术上说,柱层析是具有挑战性的。
但稍作实践,你就能够成功的持续的分离混合物。
5:As the name suggest, a common adsorbent,either silica or alumina is packed into a grass tube with the stopcock at the bottom.顾名思义,常见的吸附剂,无论是二氧化硅或氧化铝将被装在带有旋塞阀的玻璃仪器的底部。
6:The sample is applied to the top of the adsorbent and the solvent is ran through the column until the compound is flushed at the bottom.样品加在吸附剂的顶部,溶剂流过柱直到混合物冲到底部。
7:In most cases, flash chromatography is used. 在大多数情况下,快速层析法是常用的。
8:Meaning that pressure is applied to the top of the column, result in faster running time and better separation.这意味着压力施加在柱上,导致更快的跑柱时间和更好的分离效果。
9:Before you can run a column, you need to decide on the appropriate conditions.在过柱子之前,你需要决定合适的条件。
10:It is advised of you pick solvent system that will provide good separation建议你选择溶剂体系,将提供良好的分离效果。
11:In general, you will use a mixture of two mixable solvent, one polar and one non-polar.在一般情况下,你会使用两种溶剂的混合物,一种极性和非极性。
12:Luckily, TLC is an effective tool for deciding on the acceptable solvent system for your sample.幸运的是,TLC是有效的工具,它能够帮你找到你样品所接受的溶剂系统。
13:Make a TLC sample by dissolving a small amount of your material in approximately one milliliter of solvent. 用大约一毫升溶剂来溶解少量的物质作为TLC样品14:Use the sample to spot several TLC plates and develop each plates in the different solvent system.15:Make sure that the adsorbent on your TLC plates is the same as the adsorbent you will use on your column, either silica or alumina. 确保在你在薄层板上用的吸附剂和你将在柱子上使用的吸附剂相同,无论是二氧化硅或氧化铝。
16:Most commonly, you will use the solvent system composed of the mixture of ethyl acetate and hexane. 通常,您将使用由乙酸乙酯和正己烷混合而成的溶剂体系。
17:But when you purify a volatile compound, it is a good idea to use a lower boiling solvent system, such as the mixture of ether and pentane. 但当你净化挥发性的化合物,使用低沸点溶剂体系是一个好主意,如乙醚和戊烷的混合物。
18:Mixtures of methanol and dichloromethane are frequently used to purify highly polar compounds. 甲醇和二氯甲烷混合物通常用于纯化高极性化合物。
19:When you are removing small amount of impurities from sample, focus on the major constituent. 当你除去样品中少量杂质时,得到一个主成分。
20:Once you have found the solvent system that separates the components of your sample, adjust the polarity solved the major, and hopely, the desired constituent has a Rf approximately 0.3.一旦你选择了分离样品成份的溶剂系统,调整极性解决的重大,理想的成分有一个射频约0.3。
21:If the RF is too low, then the solve system is too nonpolar and it will take a very long time for the materials to come off the column.如果RF值太低,那么,那么从柱子出来就要花很长的时间22:Alternatively, if the RF is too high, then the solvent system is too polar, and the material willcome off the column very quickly with poor separation 另外,如果RF值太高,然后溶剂体系极性太大了,物质就会很快的从柱子出来,分离效果也就会很差。
23:When you are separating a mixture of two or more compounds, adjust the solvent polarity suchas the main point between the spots as the RF approximately 0.3当你要分离混有两种或两种以上的化合物时,调整溶剂极性使得主要的点RF约为0.324:When you are separating two or more compounds with very different polarity, it will save yourtime to increase the polarity of the solvent as the column proceeds当你用不同极性分离两种或两种以上的化合物时,这将节省你的时间提高溶剂的极性25:Begin the column with the solvent system that proceed least polar compound at the RFapproximately 0.3 开始列与溶剂体系的极性化合物进行至少在RF约0.326:Once that compound has completely come off the column, slowly increase the polarity of thesolvent to the mixture that puts the next spot at a RF of 0.3一旦化合物完全脱离柱子,慢慢增加混合物溶剂的极性,使得下一个点RF在0.327:Continue this until all the desired spots have come off the column继续做,直到所有想要点脱离出柱子。
28:Once you have picked a proper solvent system, you need to decide how much adsorbent to use.一旦你选定了合适的溶剂系统,你需要决定使用多少吸附剂。
29:This video will illustrate the use of the silica gel column, but the same procedure can be followusing the alumina.这段视频说明硅胶柱的使用,但是使用氧化铝可以用同样的步骤。
30:In cases with good separation, a 20:1 mass ratio of silica gel to compound is usuallyadequate. This means that for 1 gram of compound, you will use 20 gram of silica.在具有良好的分离效果情况下,质量比为20:1的硅胶化合物通常是足够的。