EA : Triethleamine : acetic acid : water was used as the gradient elution in TLC. A single spot was obtained in TLC, but in UV light it was not visible. Is my sample pure enough for NMR studies?
What's the Rf value of the spot? If it's in the region of 0.3 -0.7, then your assumption is probably correct, but if the spot is to close to the starting point or to the solvent front, you should adjust the polarity of the eluent (to give Rf value about 0.3-0.7) and repeat the TLC. Also note that the sensitivity of TLC is very low compared to GC- or LC-MS (so even if you observe only one spot, there might be some impurities in your sample).
2D TLC gives you accurate information. See your TLC in UV chamber at different wavelength.
Use iodine as a detecting reagent. If you still find a single spot, then probably u r heading on the right way. Another way to confirm single spot is to perform the HPTLC of same sample using same solvent system. As it is more precise and accurate, you will get the exact separation with good resolution and it will also rule out the possibilities of any other compound being present. Many times it happens that in TLC we get a single spot, but in HPTLC we get a different picture.
u can stain it using KMnO4 and confirm sopt with diffrent % of solvent system.Sometimes it may happen a component being highly polar gives a spot at the base line where there is a chance of misconception.
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