I wanted to create the fingerprint of a phenol rich plant extract (dried powder, 15min ultra sound extraction in methanol) following the paper of Do et al (Article Complementary developing solvents for simpler and more power...
)They use 3 different solvents to create a Fingerprint using a
a) non-polar b) medium-polar and c) polar mobile phase.
The first 2 mobile phases gave a fine separation - even though the bands (sprayed on 10µl) were a bit "thick".
The last mobile phase (ethanol, dichloromethane, water, formic acid 16:16:4:1 (v/v/v/v) though only gave elongated smear.
The plates of the 3 developments were sprayed in paralell - so the spraying or solving in Methanol or the extraction cant be the error as the other 2 developments worked fine.
Also the amount doesnt seem to be the problem - i did another TLC with different amounts of the extracts - which you can see on the attached image (application of 1-8µl of the extract, picture was taken at UV254). The samples were a bit close - but still - that was no problem on the similarly prepared plate - those gave normal bands with everything done the same way - just with a different mobile phase.
Do you have any idea what could be causing this problem? Or is it just that some mobile phases simply dont work for some samples?
Any help is greaty appreciated.
What were the other mobile phases used? The paper isn't posted at the link you provided.
One possibility is the TLC chamber isn't saturated with vapor as water and formic acid high relatively high boiling points compared to the other solvents, although that is just a guess.
Your sample could be too concentrated, and had poor solubility in the mobile phase. The 1uL spot (left-most one) didn't look too bad, and there was some separation (could make out at least two components). I would just dilute the sample in DCM, and put less on the plate. When taking the pictures, try to reduce the exposure by 1 stop, and you can enhance the contrast to see more of the weaker bands.
Have you tried to increase the distance between the spots/bands?
Sometimes our experiments run like that when the spots/bands are too close to each other.
There may be the following reasons
1. The sample concentration is too high. Dilute the sample with solvent or reduce the amount of sample.
2. The compound contains strongly polar groups. Alkaline or acidic solvents can be added to the developing agent
3. If the solubility of the sample is poor, consider replacing the developing agent.
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India