Experiment 1

Analysis of the Color of Water Soluble Inks

Procedure and Results

Procedure

The inks to be used in this experiment are of two kinds: "washable" (e.g., Fineline non-toxic water pens, Pentel colored pens, and Mr. Sketch water color markers), and "permanent" (e.g., Sharpie Permanent Markers). Using the following procedure, obtain chromatograms of one permanent and four or five washable inks in water. In addition, obtain chromatograms for a single ink using a series of solvents. Choose one of the solvent systems listed below.

1. Prepare 100 mL of each of the solvents containing mixtures of NaCl, water and isopropyl alcohol by combining in a beaker 1.0 g of NaCl and the appropriate volumes of deionized water and isopropyl alcohol. Weigh the salt out carefully on a balance, and measure the liquid volumes with a graduated cylinder.
   
   
2. Cut pieces of filter paper into rectangular strips about 2 or 3 cm wide and at least 11 cm long. Trim one end as shown.
   Use a pencil to draw a short line about 1 cm from the tapered end. Place a small spot of the ink to be analyzed on the pencil line.
   
   
3. Pour solvent into the chromatography bottles until it is deep enough to just touch the bottom of a suspended strip of filter paper. Fold about 1 mm of the filter paper strip along the dotted line and attach enough tape to it so it can be suspended across the bottle mouth as shown. Be sure the solvent does not cover the ink spot. Place the lid over the jar.
   
4. Allow the solvent to rise on the paper until it is about 1 cm from the top. Remove and use a pencil to mark the location of the solvent front. Suspend in air to dry.
   
5. Calculate the R_f value for each dye by measuring the distances traveled by the dye and the solvent using the equation given in the Background for this experiment.
   

Results

The Results section of your notebook should contain one-half of each chromatogram that you obtained. There should also be a description of the ink that was used and the solvent for each chromatogram. Make a table which lists the distances traveled by the solvent and the leading edge of each dye. Include in your table the values of each R_f value that is calculated for each dye. Under the table show your calculation so you can check them later, if necessary.