Just a quick comment from a newbie. This paper chromatography sounds
like a technique used in chemistry--thin layer chromatography. Place
a drop of your sample on a small sheet and run it in a solvent,
visualize with UV or an indicating reagent. All types of
chromatography are sensitive to concentration so red, for example, may
show up as orange or yellow depending on how much 'stuff' you have.
No spot may appear because there is too little indicator (not usually
the case) or the compound is in very low concentration. What remains
constant (in a given solvent system) is the distance that a compound
will travel on the paper. Everything else is qualitative.

If you have big fuzzy spots (as it sounds like you do), dilute the
solution a little bit before you apply it to the paper. I'm guessing
that your referring to a UV lamp in which case, UV is pretty sensitive
so you should be able to see more clearly with a less concentrated
solution.

On 23 Dec 2003 22:16:41 -0800, (Michael Brill)
wrote:

>So I'm staring at the results from a MLF test and I'm wondering if
>there's a faint indicator of malic acid or it's just the lights.
>Paper chromatography seems very qualitative - I'm 90% sure that malos
>are complete as I don't see any dots for malic acid, but it's all very
>blue/yellow/green and fuzzy. Even the testing documentation stated
>that when there is no longer any dot there still may be some malic
>acid left. When does one declare victory?