Is it good to use absolute ethanol or diluted ethanol for extraction of phytochemicals?
Ethanol is used as a basic and common solvent, but according to the objectives of the study, check the available literature.
Regards
Extraction of phytochemicals are affected by so many factors ranging from their thermo libile nature or their polarity. Ethanol as a solvent is liable to extract polar phytochemicals. However absolute alcohol because of its high purity level are better solvents than it's diluted version, whose purity might also be in doubt.
Methods of extraction is also an important factor. Is the extraction by soxhlet where a heating mantle is required or using maceration. High level of purity is required in all isolation of metabolites or phytochemicals.
Diluted methanol will be preferable to get enough yield of the crude extract thou it will take enough time during soxhlet extraction to extract all the water present in your plant material because it's highly polar as compared to a absolute methanol Which will take a shorter time to extract.
The question to your question is 'What is your target group of phytochemicals? if they are polar, then ethanol (80%) or absolute is still fine. You can substitute it with methanol. But if you are targeting oils or other non-polar compounds then non-polar solvents like hexane will be best. The choice of solvents depends on a number of issues like polarity of target compounds, method of concentrating i.e. rotary evaporation, use of the extract, etc
For flavonoids extraction I in my practice usually use 70% ethanol. If you have 96% ethanol you can diluted it by distilled water using the special table of dilution up to 70%.
But you should remember, that a differents chemical structure compounds are extraction of differents solvents. For example, for polysaccharides it can be water like extragent and after that carry out precipitation with ethanol. If you need to study some lipopholic compounds like extragent better use chloroform of hexane.
indeed, for the extraction of Flavonoid glucosides, flavonoids (flavonols), Phenolic acids, tannins, terpanoids, Anthocyanins and alkaloids we use 70% or 80% ethanol, this is the best extraction solvent because methanol is toxic, and if you want to know exactly what percentage gives you the best yields you could optimize your samples
It depends on your desired phytochemicals. Sometimes different compositions of alcohol are more beneficial than absolute alcohol.
Adding water to ethanol(70%) means an increase in the polarity of the solvent, and this process helps in extracting more polar compounds without resorting to methanol as a solvent.
We are basically 70% Ethenol in my Phytochemical Analysis practice because increase in the polarity of the solvent and easy to extract all chemical constituents compare to absolute ethanol.
Use absolute ethanol (99%) to extract Phytochemicals from the plants. Because Ethanol will retrieve a large amount of oil from the plant and then completely evaporate.
Use of Absolute Ethanol is preferred. Because is water is present in Ethanol, starchy components will get extracted, which will will interfere in the subsequent chromatographic separation either by HPTLC or HPLC. If have rectified spirit of 93 % plus 7 % water, mixed with 15 gm Anhydrous Sodium sulphate and drain the Ethanol devoid of moisture. Anhydrous Sodium sulphate is not soluble in Ethanol but i traps all the water part.
To investigate the suitable pourcentage of ethanol to extract phytochemicals, you must investigate the critical-factor infuence on the extraction, you used a single-factor experiment to determine a ranges of water percentage in ethanol, temperature of extraction, and a time on total flavonids content. also, you can considered others factors.
Exactly Mr. Nadjet. The ratio of Ethanol to water is different for different herbs. But screening of Phytoconstituents of a less evaluated plant, Methanol is ideal, that takes care of Phytochemical species. Then the methanol extract may screened with quality test of all Phytochemical classess.
Rajesh S Mony, Thank you for your answer, methanol gives better extraction yields, taking into account its toxicity, agrosolvents and eutectic solvents are more used.
You are right. But for the accurate and precise Analytical requirement Methanolic extraction is opted. Usage of Soxhlet extraction apparatus in fume hood is ideal to avoid atmospheric contamination of Methanolic fumes.
Once analysis is completed for bulk level of extraction one can choose any other Solvent or Solvent mixtures according the polarity of the target Constituents. It may also noted that Methanol is among the prominent solvent used for extraction of Spices and other Medicinal herbs. Factory and Boiler Inspectorate of India has different conditions of issuing permits that specifies conditionalities including huma safety and fire hazards.
If you are doing bioactivity guided, please make two extracts,in ethanol and 1:1 ethanol-water, check bioactivity and go ahead with the more active one.
If your focus is on chemistry of compounds, then check TLC & HPLC of both extracts and pick the highest compound containing extract for further study.
Well, there is obviously no direct answer, but I think dilute ethanol (50%V/V) would get you what you want. Decoctions are also a very good extraction technique. If there is not much literature on this plant and you do not know exactly what you’re extracting, you probably should also extract using some non-polar solvents because your target extract(s) might just be non-polar.
The purpose of the study must be kept in mind. Whether it is a specific class of substances that is being researched or a more general analysis of the constituents of the plant or any other product of natural origin. My suggestion is to carry out extractions with solvents of different polarities and try to identify the substances obtained
This depends on what substance you want to extract, such as chloroplast pigments that are not easily soluble in anhydrous ethanol, so diluted ethanol needs to be used.
Identify the characteristics of the sample to be extracted and determine what analyte is the target, then relate it to articles that have been published by other researchers. From this, you can determine the type and concentration of solvent to be used for extraction. You can also optimize the type and concentration of solvent using Response Surface Methodology in the extraction process.
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