Do simple chromatography

Content

To step
Part 1 of 3: Creating a sample
Part 2 of 3: Adding a solvent
Part 3 of 3: Observing the tires
Tips
Warnings
Necessities

Mixtures consist of two or more components that have different properties. There are many methods of separating mixtures into their basic components. For liquids, these methods are called chromatography. In chromatography, a mixture is separated into its components based on their relative ability to move through the stationary phase (solid phase) by means of the mobile phase. Some components of the mixture pass through more easily, while others are held back. This ensures that the mixture separates into bands of different components.

To step

Part 1 of 3: Creating a sample

Make or buy a chromatography strip. A chromatography strip is a strip of material through which the mobile phase mixture (a liquid or gas) moves. The strip serves as the stationary phase, so you can see the speed of movement of the different components in the mobile phase. You can purchase specially formulated chromatography strips for superior results, but you can create your own for basic chromatography. Cut a coffee filter into straight strips about 2-3 cm wide and 5-6 cm long.
- You can also use paper towels or any other paper instead of the coffee filter.
Place a colored line at the bottom of the strip. Measure about 2-3 cm from the bottom of the strip. In this experiment, you will separate the components with a highlighter. Use a black highlighter to draw a straight line across the width of the strip. Make sure the line is high enough so that you can submerge the bottom of the paper without submerging the line.
- Instead of a line, some people use a period. This will work too, but the bands will not be as clearly defined with this method.
Fix the chromatography strip vertically. Secure the strip vertically with clothespins so you don't have to put it in the water yourself later. It should be hung so that the side with the marking line is closest to the ground. Make sure the clothespin is placed as high on the strip as possible, while still holding it securely. If the clamp is too far down on the strip, it can affect the straps.
- You can hang the strip with paper clips, tape, or any other suitable method.

Part 2 of 3: Adding a solvent

Put water in a cup. In simple chromatography, your solvent (the liquid that carries the mobile phase through the stationary phase) is water. Add a little water to a clear cup or glass. You only need enough to wet the chromatography strip, so a few deciliters is enough.
Lower the chromatography strip into the water. Hold the chromatography strip vertically and lower it into the water. Make sure you've constructed something to hold the strip there as this process can take quite a bit of time. The bottom of the strip must be submerged, but the marker line must not be submerged. If you accidentally submerge this line, discard the strip and make another one.
- An example of a construction for leaving the clothespin holding the strip to a pencil above the top of the glass. That way the strip dangles down and barely touches the water.
Please wait patiently. As the water is absorbed by the strip, it will carry the various compounds in the post. The lighter (smaller) fabrics will move faster, and the heavier (larger) fabrics will move slower. This will separate the compounds into "bands" based on their size. However, this is a slow process. Watch the strip until you see that the water is about 2-3 cm from the top of the strip.
- The exact time it takes for the water to get up to 2-3 cm from the top of the strip depends on what type of strip you are using.
- Do not wear the system after submerging the strip - avoid any kind of agitation that will affect the result by spreading the tires.

Part 3 of 3: Observing the tires

Remove the strip from the water. Place it on a smooth surface and wait for it to dry.
Count the visible bands. Once you remove the strip from the water, the straps should stay in place. This way you can count how many different tires are visible on your strip. That will give you a rough idea of how many different sized compounds are in the marker ink.
Note the color of each band. The black ink of the marker consists of different pigments. These pigments all have their own unique colors. When you separate them into bands, the bands are the color of that individual pigment. By noting the color of each band, you can analyze which colors are the pigments of the black ink in the marker.
List the bands from the top of the strip to the bottom. Write down the colored bands according to the distance they traveled. The bands at the top are your lightest connections and the bands at the bottom are your toughest connections. You will also likely notice a top to bottom color trend. Lighter colors tend to be smaller joints, so move further up the strip - darker colors will stick more to the bottom, as they generally have heavier joints.
- The ratio of the distance a compound has moved (Dc) to the distance the solvent has moved (Ds) is called the Rf value. You can calculate the Rf value for each tire by dividing the distance the tire traveled from the origin by the distance the solvent traveled from the origin.
- For example, if you have a band that is 2 cm above the origin, and the solvent is 5 cm above the solvent, you can use the equation D_band/ D_solvent = Use Rf. In this example that means:
  - Rf = 2 cm / 5 cm
  - Rf = 0.4

Tips

If you want to do this more scientifically, you can actually buy chromatography paper, which is similar to a coffee filter, but creates a much clearer and less blurry band of colors when used properly. This is available through various laboratory equipment suppliers.
Try different colored markers, noting which one reaches the top first, which creates the most beautiful bands of pigments, and so on.
Chromatography is used in real scientific labs for a variety of reasons, and can get quite complex. Chromatography involves a wide variety of scientific tests and is not limited to this method.
Make sure the marker is water soluble before doing anything. Permanent marker does not usually work for this experiment.
Why does this work? Different colored pigments have different shapes at the molecular level and are drawn differently across the paper due to the difference in the relative affinity of the components with the mobile and stationary phase. This is also technically referred to as a distribution coefficient or partition coefficient. This forms a long strip of pigments that line up, with the most similar colors closest to each other.