There are no more demos planned, since the lab course is over. the video is of separating components of felt tip pens, but it’s also neat. Note how poorly silica works and how different the Rf’s are between silica and filter paper. I’ve got lots of pictures from my experience (click for larger). But it looks like the blue in the blue M&M is a different blue than the blue in the green and brown M&M. Rather, there is one orange spot with a larger Rf than red. As you might expect, green separates into blue and yellow, but surprising the red and yellow of the orange M&M do not separate. There are 5 food coloring agents in M&Ms: Red 40, Yellow 5, Yellow 6, Blue 1, and Blue 2. Typical uses include coated tablets, cake and donut mixes, hard candies and chewing gums, lipsticks, soaps, shampoos, talc, etc. Lakes are more stable than dyes and are ideal for coloring products containing fats and oils or items lacking sufficient moisture to dissolve dyes. Lakes are not oil soluble, but are oil dispersible. Lakes are the combination of dyes and insoluble material.
Dyes also have side effects which lakes do not, including the fact that large amounts of dyes ingested can color stools. They can be used in beverages, dry mixes, baked goods, confections, dairy products, pet foods and a variety of other products. Dyes are manufactured as powders, granules, liquids or other special purpose forms. It’s all in the formulation:Ĭolor additives are available for use in food as either “dyes” or “lakes”.ĭyes dissolve in water, but are not soluble in oil. At least, not as far as the compound responsible for the hue is concerned. Pop quiz, hot shot: Do you know what the difference between Red 40 and Red 40 Lake are? I didn’t either. I used the largest filter paper we had, and ran the chromatograph twice to get the results shown.
The more distance you give the colors to separate, the better the results. The paper will start to buckle and it will droop and fall over if it is not creased first. Who knew? Also, you should put a crease in the coffee filter before placing it in the solvent. Then I switched over to filter paper, and all of a sudden I got the results I was expecting. I also noticed that according to the websites I was looking at, red should have travel the shortest distance. I tried several different solvents… no luck. I was quite disappointed because the red and yellow both travelled with the solvent front and there was little separation. I started by spotting the colors on my silica gel TLC plates. Quite interestingly… the stationary phase matters. Watch the colors separate like magic!Ĭouple’a observations I noticed. Put the coffee filter into a 1% solution of table salt and allow the water to rise through the coffee filter. Use a toothpick to spot each color onto the coffee filter. Allow for the water to strip the color off the colorful candy shell. Basic rundown: put drops of water on wax paper, and put a piece of candy on each drop. If you’re interested, other proceedures are available here, and here. You can separate the colors contained in M&M shells (or Skittles, or Reese’s Pieces, or Sharpies, etc) through chromatography. This one’s a do-it-yourself demo, if you’d like. Last lab of the semester means last demo of the semester. They could physically watch it run down the column, then only collect the yellow fractions. Students were aided this week in that their product was bright yellow. These differing affinities allow for one compound of interest to be separated from a mixture through the use of column chromatography. Suffice it to say that different organic compounds have differing affinities for a stationary phase versus a mobile phase. I’ve talked about the theory behind column chromatography before, so I won’t rehash it here in any detail. They purified their crude product mixture from last week’s nitration lab. This week the students practiced column chromatography. *For more cool stories, pictures, and videos of chemistry demonstrations, click here*
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