I am trying to use a method from a paper by Do et al (https://www.sciencedirect.com/science/article/abs/pii/S0021967320311043?via%3Dihub) for a plant fingerprint.
Short version: what could be causing the "blurred" lower third of the TLC plate that?
In the paper they use three mobile phases with different polarities to achieve that.
1. Toluene, ethyl acetate 9:1
conditioning 33% r.H. (10 min); no saturation
2. Cyclopentyl methyl ether,tetrahydrofuran, water, formic acid 40:24:1:1
conditioning 33% r.H. (10 min); saturation (20 min, saturation pad)
3. Ethanol,dichloromethane, water, formic acid 16:16:4:1 ;
conditioning 33% r.H. (10 min); saturation (20 min, saturation pad)
Conditioning is done by using a saturated aqueous solution of magnesium chloride.
A problem i dont know what may have solved is appeared when using mobile phases 2+3, conditioned and in a satured twin-through chamber.
The lower part of the TLC plate (silica gel f254 by merck) got blurry - where normally you could see the starting points of the samples. The image best shows what i mean (magnify to see the whole problematic lower part i talk about). This appeared on several plates - all those were in a saturated chamber (whatman paper over the back through with mobile phase pipetted to wet it, then 20min before inserting the plate)
I dont know what is causing this problem - as so far i mostly worked with low polarity mobile phases. But as it appears when i try to saturate the chamber my guess its related to that.
Do you have any idea what could be causing this and how to prevent this problem?