Science Buddies: "Ask an Expert"

I need help with the paper Chromatography of the food colors on Skittles. All colors (purple, red, green and yellow) are doing what I've expected. They separate (green and purple) and don't (red and yellow). Orange is the the color that acts out of the expected. Shouldn't it separate in red and yellow? It doesn't, it just stays orange. As orange is not mentioned on the ingredient list, I wonder if it is considered some type of red or if the dyes used to make it, simply do not separate in the two developing solutions I have used? Those were 1% Salt Solution and 91% Isopropyl Alcohol.
Any suggestion helps! Thanks!

Hello,
Technical, since Skittles uses food dyes, the orange be soluble in a salt solution. But, I have noticed that on other peoples' projects, their orange didn't separate either. This may be due to the fact that in both of the solutions you used, all of the separate dyes used in the orange mixture have the same solubility in those solutions and affinity for chromatography paper, making it so all of the dyes travel the same distance up the paper. Other than that, I don't know what could be happening, and I don't have access to actual chromatography paper so I see it for myself at the moment. I'll ask some other experts to see if they can help with your question.

-Meg

Meg, thanks for your elaborate answer. I changed to M&Ms in the meantime. Didn't change the outcome of the orange - though. I think the orange is simply the food color Yellow 6 because I found out that this color is responsible for an orange shade, it is called Sunset yellow. If they used that for the orange M&Ms - or Skittles - it won't separate of course. I have another question, now that I found someone interested and knowing: Can I separate the lakes and the dyes of the same color or do they stay together with this method? Might be a stupid question, I know. But if they just stay together then I am not going to specify lakes and dyes in my experiment and just mention them as one color group. Thanks

Sorry it took me so long to respond, but I'm normally on the forum on Saturdays (I'll follow this thread, so if you have any more questions I can answer them sooner). Your explanation on the orange pigment does make sense, and as for your question, most lakes tend to be insoluble compounds, therefore if any of the pigment is still at the bottom of the paper strip, or low on the strip, it most likely is a lake (because the more soluble (the more easily something dissolves in something else) the pigment in the solution, the further up it will travel). Dyes are water soluble, or they dissolve in water, so they should be further to the top on the paper.


I hope this helps!
-Meg

Meg, thanks again! You really helped me! It is hard to tell the difference between the lakes and the dyes. Due date for the project is next week, so I'll be wrapping it up over the weekend. Thanks again!

I'm glad I could help you! Good luck with the rest of the project!

-Meg