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How to Measure the Chromatogram Dye

Liquid chromatography is an analytical tool used to identify chemicals or dyes based on their size or structure. A sample of the chemical or dye is placed on a medium such as filter paper, and the filter paper is placed into a solvent, such as acetone or ethanol. As the solvent wicks up into the filter paper, it will carry the sample with it. You can use a ruler to measure the distance the dye traveled from the starting point, which will give you critical information about the chemical.

Things You'll Need

Acetone
Dye
Filter paper
Scissors
Chromatogram
Ruler
Pencil
Glass

Instructions

- 1
  
  A starting line is required in order to determine how far a dye as traveled.
  
  Cut a strip of the filter paper about one inch wide and five inches long. Use a ruler and pencil to draw a line across the filter paper near the bottom where the sample will be placed. This is the starting point of the chromatogram.
- 2
  
  Only a small amount of solvent is needed to develop a chromatogram.
  
  Pour just enough acetone to completely cover the bottom of the glass. Place a sample of the dye in the middle of the filter paper on the starting line. Put the chromatogram, sample side down, into the glass.
- 3
  
  The dye will absorb into the filter paper similar to a pen-ink spot on a shirt fibers.
  
  Circle the area to where the dye was carried after a couple of minutes. Use a ruler to measure the distance from the starting line to the circled area as well as the distance from the starting line to the solvent boundary.
- 4
  
  Some division is needed to find the retention factor of a dye in order to identify it.
  
  Calculate the retention factor, which is the ratio of the dye distance to the solvent distance.
  
  For example, a particular dye had a distance of six centimeters from the starting line, and the solvent had a distance of twelve centimeters. The retention factor for that dye would be 6/12 or .5. No matter how long that particular dye was left into the solvent, the retention factor would always be the same.

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