Pumukli - 5-8-2022 at 09:42
Something to think about - at least for me, to entertain myself. 
On the picture you can see a "tlc" developed on a piece of el-cheapo brand printer paper. So it is a paper chromatogram, technically.
I was wondering whether something as simple as this could be used instead of the more expensive real TLC plates. It seems it might. 
I tried real filter paper, but the result was a big disappointment. But this printer paper is not that bad for starters. Well, I've never seen a real
paper chromatogram, so I'm biased.
Very simple experiment but raises several questions:
- On the starting line there were 3 different dyes spotted. On the developed chromatogram only two can be seen. What happened to the third one?
(Actually the first one is missing, if we go from left to right.)
The missing spot was methylene-blue (dissolved in denatured ethanol, as were all three dyes). I "swear" it was on the starting location (albeit a bit
less intense than the other two), but by the time the run ended, it practically disappeared. May the paper contain some sort of reducing agent that
turned it into the leuco-form?
- The middle spot is bromo-thymol-blue. It looks relatively OK, Rf is very high, basically run together with the solvent front or only a touch behind.
It is not blue, because the solvent was something like denatured ethanol mixed with toluene and acetic acid, so we can see the low pH color.
- The rightmost spot is a diffuse one. It is bromo-phenol-blue. It looks as if this dye had some other stuff as well. It produced a stationary spot at
the start line, which did not changed colour either, remained blue even in acetic acid. And the diffuse "head" spot has different colours (if you can
see)...
Accidentally I came across an article that dealt with the paper chromatography of this particular dye and stated that bromophenol-blue is not a stable
dye. Maybe we can observe its "unstability"?
Thoughts?
