TLC Spot Extraction & Compound Isolation for UV ID

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In summary, the best method for extracting a compound separated by TLC is liquid extraction following spot isolation and visualization using UV and scraping absorbent silica from the plate. It is recommended to use a reference solution of methanol for the extraction, but it should be noted that methanol may dissolve the silica gel which could affect the spectra. An alternative would be to use ethanol and then dry and redissolve the residue in the desired solvent. For the compound to be used in different pH solutions, it is advised to use a volatile solvent for extraction, drying, and then redissolving the compound in the appropriate pH solution. Extreme pH may dissolve the silica gel coating, so care should be taken in selecting a suitable solvent.
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~christina~
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I am wondering what is the best method to use to extract a compound that is separated by TLC by the liquid extraction method following spot isolation (visualization using UV and scraping absorbent silica from plate) for identification by UV spectroscopy.


I originally used methanol for extraction of the unknown compound and analyzed solution with plain methanol for the reference solution. Problem is that I read that methanol dissolves silica gel. I assume that this would affect the spectra? (not sure how)

1. Assuming that it would affect the qualitative identification of a compound by UV , would the problem be solved by using a reference solution of methanol (after using it to 'extract' silica scraping from part of plate without desired compound).

Or should I just use ethanol, separate extract, dry and then redissolve residue in whatever solvent I need compound to be in?

2. Second issue is that I need the compound in different pH solutions (10 & 2). Could I use the acidic/basic aq solutions for extracting silica or would that dissolve it as well ? From what I read, extreme pH will dissolve the silica gel coating. Is the solution for this to also extract using a volatile solvent (having trouble picking one that will leave gel and extract out compound:confused:), drying, and redissolving it at needed pH?

Thanks
 
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Silica gel dissolves in methanol? Sounds strange to me. You could of course try it out and extract some clean silica gel with methanol and compare the spectrum with that of pure methanol.
 
  • #3
DrDu said:
Silica gel dissolves in methanol? Sounds strange to me. You could of course try it out and extract some clean silica gel with methanol and compare the spectrum with that of pure methanol.

What I'm referring to is from what I read here: http://www.chemicalforums.com/index.php?topic=50163.0

I was going to try what you mentioned from a practical point but was wondering if anyone knew about this.

Also, what about my second dilemma regarding extraction to solutions of different pH and effect on the silica gel? Would I have to use organic solvent to extract, dry the solvent and then redissolve compound in aqueous base/acid solution?
 

FAQ: TLC Spot Extraction & Compound Isolation for UV ID

What is TLC spot extraction and compound isolation for UV ID?

TLC spot extraction and compound isolation for UV ID is a technique used in analytical chemistry to separate and isolate individual compounds from a mixture using thin-layer chromatography (TLC) and ultraviolet (UV) light detection. It involves spotting the mixture onto a TLC plate, developing the plate in a solvent, and using UV light to identify and isolate the desired compound.

How does TLC spot extraction and compound isolation for UV ID work?

The TLC plate is first spotted with the mixture, and then it is placed in a solvent that is allowed to travel up the plate. As the solvent moves, it carries the different components of the mixture at different rates, causing them to separate. UV light is then used to visualize the separated compounds, and the desired compound can be extracted from the plate for further analysis.

What are the advantages of using TLC spot extraction and compound isolation for UV ID?

One of the main advantages of this technique is its simplicity and low cost. It also allows for the separation and identification of multiple compounds in a mixture, making it a useful tool in drug discovery, forensic analysis, and other fields. Additionally, TLC plates can be easily prepared and stored for future use.

What types of compounds can be isolated using TLC spot extraction and compound isolation for UV ID?

TLC spot extraction and compound isolation for UV ID is useful for isolating a wide range of compounds, including organic compounds, inorganic compounds, and biomolecules such as proteins and nucleic acids. It is particularly effective for compounds that are sensitive to heat or cannot be separated by other methods.

Are there any limitations to using TLC spot extraction and compound isolation for UV ID?

While TLC spot extraction and compound isolation for UV ID is a versatile technique, it does have some limitations. It may not be suitable for separating complex mixtures or compounds with similar properties. It also requires some expertise and careful interpretation of the results to ensure accurate identification and isolation of compounds.

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