[Friedferrous]

I have a gel filtration chromatography lab manual and I'm confused on the wording on a certain protocol: "determine the volume at which each of the three colored molecules elutes ( visually estimate which tube has peak fraction of each colored molecule). I'm thinking this means the following- when you elute you may not get a completely pure fraction (I.e. You get a few drops of one fraction in another fraction. You are supposed to visually estimate color to determine where one fraction concluded (I.e. Look at color intensity versus color of pure compound to estimate volumes of each fraction.

Can anyone clarify?

[Babcock_Hall]

Let's assume that the resolution (separation) is very good, and there are no mixed fractions.  Let's also suppose that each compound elutes in more than one fraction.  What do you think you will see, and why?

[Friedferrous]

I think I figured this out: if you take fractions, initially they will be clear and slowly will become colored- the peak fraction has the greatest color intensity before the fractions clear again?

[Arkcon]

That is correct.  You will name the fraction for this peak based on when the highest point came through.  And you got it right.  Now, you can name it fraction number, you can name it by time, you're called on to name it by volume, and you can use your tubes for that info.  You also seem to be a bit worried about the width if the peak-- where they start or that they've run together.  And you can note that information.  But you will be called to find peak apex, and you have found it.

ETA

Sorry folks, I spell better when I'm not on my phone.