I want to study the phytochemicals in Petroleum ether, chloroform, and methanol plant extract Please suggest me which solvent system is best for each crude extract. And also suggest techniques used for the separation of phytochemicals from plant extracts and their characterization.
thank you
The common procedure is starting with non-polar solvent ( n-hexane or petroleum ether) to separate the oils and fats ( like-dissolves-like) followed by ethyl acetate, then methanol, finally with 70% methanol, to fractionate the plant constituents .
Check each extract using TLC in order to know the number of components in each fraction. separate them using chromatographic techniques e.g. MPLC ( the best), or column chrom.....etc
Finally, identify the single separated compounds by spectroscopic methods, IR, H1NMR, C13NMR, DEPT, COSY, NOSY , MS., Element Analysis..etc.
You can start from low polar to high polarity solvent combination like toluene : ethyl acetate.
I note that your plant extracts are in very different solvent polarities.
Petroleum ether is is least polar, and it will extract non-polar compounds such as terpenes, and waxes. Useful TLC mobile phases would be hexane/ethyl acetate, hexane/ether, and hexane/dichloromethane. You can substitute petroleum ether, cyclohexane, or heptane for hexanes within this reply.
Chloroform tends to dissolve more polar compounds. Hexane/ethyl acetate, Hexane/dichloromethane, and dichloromethane methanol would be solvent system I would try. You will notice I mention some solvent systems multiple times because they work well with compounds having a wide range of polarity. In addition, some compounds may appear in more than one extract. For example, a moderately polar compound may be in tour chloroform and methanol extracts.
A methanol extract is more polar still. Hexane/ethyl acetate, dichloromethane/methanol would be good starting points.
The common procedure is starting with non-polar solvent ( n-hexane or petroleum ether) to separate the oils and fats ( like-dissolves-like) followed by ethyl acetate, then methanol, finally with 70% methanol, to fractionate the plant constituents .
Check each extract using TLC in order to know the number of components in each fraction. separate them using chromatographic techniques e.g. MPLC ( the best), or column chrom.....etc
Finally, identify the single separated compounds by spectroscopic methods, IR, H1NMR, C13NMR, DEPT, COSY, NOSY , MS., Element Analysis..etc.
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