The solvent toxicity is one of crucial factor, even though the identified solvent showing maximum yield of target compound. what are your suggestions?
Dear Selvaraj Kunjiappan, in order to avoid toxic solvents, I would suggest to start with ethanol or mixtures of water and ethanol. Attached is an interesting article describing this process for herbal extraction. Good luck!
Depends on the polarity of compounds which you want to extract. For e.g., ethanol is the safest for phenolics/flavonoids extraction. Supercritical CO2 is the safest and the most versatile solvent, but also the most expensive.
Hi Selvaraj Kunjiappan, I fully agree with Miona Belović that supercritical CO2 is an excellent solvent for the extraction of various natural products (e.g. caffeine from coffee beans). However, you need special equipment to handle supercritical CO2 under pressure. For "normal" labs, non-toxic organic solvents such es ethanol should be fine.
Thank you Prof. Frank T. Edelmann & Miona Belović for your valuable guidance. I am concentrating to extract some anticancer agents from medicinal plant via microwave-assisted extraction.
Hi selvaraj....
If one does not know about the nature of components of the mixture to be separated, the best eluent is found by trial and error, using small, very rapid running TLC plates.
If one knows the chemical nature of the solutes to be seperated, it is possible to know a suitable solvent by using original Stahl's triangle.
I suggest to read this review:
Article A Critical Analysis of Extraction Techniques Used for Botani...
From Traditional methods of extraction to new techniques.
Before selecting the solvent one should decide on the category of secondary metabolite, which is target. If the secondary metabolite is polar solvent soluble, ethanol and waermay be used in varying concentrations. If the secondary metabolite is soluble in nonpolar solvent one can use pet ether or chloroform. Otherwise one can use successive extraction proceedure, starting with, pet ether follwed by chloroform, ethyl acetate, alcohol, water. The procedure for this is clearly explained in literature.
I agree with Ramachandra sir, but i think hydroalcoholic solvent is preferable because its also having various benefits
Ethanol is preventing bacterial growth in extract and also helpful to extract flavonoids and phenolics
Water is more polar solvent to extract polar sec metabolites
Again it will less hazardous to human and having minimum toxicity
So combination of water and ethanol may be good for herbal formulation.
It is to clarify one point here. The alcohol or any solvent will not be present in the dried extract. Therefore the antibacterial effect may not be there in dried alcoholic or hydro-alcoholic extract.
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