Questions tagged [chromatography]
collective term for a set of laboratory techniques for the separation of mixtures
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Does molten metal liquid chromatography exist?
Liquid chromatography is used to analyze and purify different chemical samples in a solvent. It is also used for industrial scale chemical purification. I was wondering if something similar exists for ...
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Typesetting of the retardation factor (Rf)
What should be the typesetting for the symbol of the retardation factor as used in thin-layer chromatography?
These are the possibilities:
Rf - only f in italics
Rf - both R and f in italics
Rf - ...
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Gas chromatography/mass spectrometry: Can I use peak ratios and molecular mass to derive quantity?
Can derive the quantity of a substance from a GC/MS report if I know:
the ratio to another substance in the data,
the quantity of that second substance, and
the molecular mass of both substances.
...
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How to separate two diastereomeric amines?
I am developing a method to synthesize amines using organometallic catalysts and my reaction yield these two diastereomeric amines ($\ce{R2N}$ is, in this case, a morpholine group).
With both being ...
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HPLC: peak area vs concentration
Many text books say that there is a proportionality between the peak area of the chromatogram and the concentration. However, in my opinion, there should be a proportionality between the concentration ...
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Silica turning transparent during column chromatography with chloroform
Initially, my column had been loaded with n-hexane and ethyl acetate, however I ended up having to use a more polar solvent to elute my product. It was my first time running chloroform through a ...
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Removal of tetrabutylammonium from an organic reaction
I need to synthesize some organic compound for my Ph.D. research. Everything went OK during the synthetic route but got messed up at the very end. In my final step (once the final compound has been ...
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What is the Kovat's Index used for?
As mentioned in the title, why do we use the Kovat's Index in gas phase chromatography? It seems a little arbitrary to compare everything to the order that n-alkanes (such as n-pentane, n-hexane, and ...
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How to choose a proper chromatography method to separate substrates?
I'm a freshman and I recently learned how to do TLC and column chromatography. I also know a little about other ways to separate things by chromatography, such as affinity chromatography, gel ...
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How to translate the mobile phase from thin layer chromatography to column?
I recently was told that once you find a good solvent mixture for separation on thin layer chromatography (TLC), you should only use 10% of the more polar solvent (for silica) when you run your column....
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If the polarity of the solvent increases, will the Rf value increase or decrease?
True or False: A sample of aspirin has an $R_f$ value of 0.20 when measured on a silica gel TLC plate with a certain solvent mixture. If the polarity of the solvent is increased, the $R_f$ value of ...
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What would a (gas) chromatogram look like if two compounds have the same retention times? [closed]
In gas chromatography, the number of peaks represents the number of compounds in an unknown sample, as retention times for each component differ.
But what would happen if two components have the same ...
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In High Performance Liquid Chromatography, why are ratios of solvents used?
How do they allow for better separation? For example, why isn't 100% hexane used?
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Why are amber bottles used to store Water for HPLC?
Image Source: https://www.calpaclab.com/water-hplc-spectro-grade-4-liter-bottles-case-4/ted-ws2211-001
When ordering HPLC/Spectro grade Water for HPLC from certain vendors(not all), it comes in an ...
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What is the purpose of trimming the bottom corners of TLC plates?
During my chemistry lab course, I was told by my instructor to make 2 small cuts on the bottom corners of the TLC (Thin-Layer Chromatography) plate. Does this make the solvent rise uniformly on the ...
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