Please answer questions 1 and 4. Explain. Once the adsorbent is packed in a liqu
ID: 948428 • Letter: P
Question
Please answer questions 1 and 4. Explain.
Once the adsorbent is packed in a liquid chromatography column, it is important that the level of the elution solvent not drop below the top of the adsorbent. Why? What precautions must be taken when you introduce a mixture of compounds to be separated onto a liquid chromatography adsorbent column? What effect will the following factors have on a liquid chromatographic separation? (a) too strong an adsorbent; (b) collection of large elution fractions; (c) very slow flow rate of the mobile phase. Arrange the following compounds in order of decreasing ease of elution from a column of silica gel: (a) 2-octanol; (b) 1,3-dichlorobenzene; (c) tert-butylcyclo-hexane; (d) benzoic acid. Why do silica gel columns with smaller particle sizes produce more effective chromatographic separations?Explanation / Answer
1. If level of the eluting solvent is above the adsorbent then the mechanism by which it is eluting will be hindered. here the the solvent elute via capilary mechanism , if the solvent level is up then that capilary action will fail , and you will not get desired result .
4. Decrease ease of elution :
that is the compound is more polar it will be difficult to elute and in this series it will come last.
so , order is
(c) , (b) , (a), (d)
(c) being the least polar and (d) being the most polar and difficult to elute.