This experiment aims to calculate the retardation factor (Rf) of madder and turmeric using thin layer chromatography (TLC). TLC involves a stationary phase, such as a coated plate, and a mobile phase solvent. Samples are spotted onto the plate and developed in the solvent, which travels up the plate via capillary action. The Rf is calculated by dividing the distance traveled by the compound by the distance traveled by the solvent front. The results showed madder had a lower Rf than turmeric, indicating it is better for dyeing applications and has better color fastness. Calculating Rf values using TLC is important for understanding dye compounds.

1. Experiment No.: 0 Experiment Name: Calculation of Rf for madder & turmeric. Introduction:
To calculate Rf of Madder & Turmeric we need TLC methods. TLC means Thin Layer Chromatography, which is classified in chromatography section of chemistry. Chromatography comes from Greek words chroma (means color) and graphein (means to write). To separate non-volatile mixtures is the main criteria of TLC. There are two phase in TLC: stationary phase & mobile phase. Stationary phase is a sheet of glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide, or cellulose and mobile phase is a solvent or solvent mixture is drawn up the plate via capillary action.
The retardation factor (Rf) is defined as the fraction of an analyte in the mobile phase of a chromatographic system like TLC method. The retardation factor (Rf) is defined as the fraction of an analyte in the mobile phase of a chromatographic system. 푅푓= 푥 푦
Here. 푅푓 = Retardation factor
푥 = distance traveled by the compound on mobile phase
푦 = distance traveled by the solvent front on stationary phase
Figure 2: Development of a TLC plate, a purple spot separates into a red and blue spot (courtesy: wikipedia.com)
For example,
If a compound travels 2.1 cm and the solvent front travels 2.8 cm, the Rf is 0.75.
Figure 1: Separation of black ink on a TLC plate (courtesy: wikipedia.com)
Figure 3: Example of retention factor (courtesy: gxnu.edu.cn)

2. Objective:
 To know About Thin Layer Chromatography (TLC) & its mechanism.
 To know About Chromatography.
 To know about Retention Factor (Rf).
 To calculate Rf of madder and turmeric by TLC method.
Apparatus:
o TLC plates
o Pencil
o Ruler
o Solvent
o Pipettes
o Pasteur pipettes
o Beaker
o Gas Burner
Procedure of TLC in our Lab:
Step 1: Prepare the developing container
The developing container for TLC can be a specially designed chamber, a jar with a lid, or a beaker with a watch glass on the top. Pour solvent into the chamber to a depth of just less than 0.5 cm.
Step 2: Prepare the TLC plate
TLC plates used in the dyeing labs are purchased as 20 cm x 20 cm sheets by our Chairman Sir. Each large sheet is cut horizontally into plates which are 5 cm tall by various widths; the more samples I planned to run on a plate, the wider it needs to be. Then we cut the 20 cm x 5 cm TLC plate with three equal part for three group.
Measuring 0.75 cm from the bottom of the plate. Using a pencil, we draw a line across the plate at the 0.75 cm mark. This is the origin: the line on which I would spot the plate. Taken care not to
Figure 4: Apparatus (courtesy: google.com)
Figure 5: Developing container (courtesy: orgchem.colorado.edu)
Figure 6: Prepare the TLC plate (1) (courtesy: orgchem.colorado.edu)

3. press so hard with the pencil that you disturb the adsorbent. Leave enough space between the samples so that they do not run together; about 4 samples on a 5 cm wide plate is advised. Also we give another mark on the upper side at 0.50 cm which is measuring from upper side.
Step 3: Spot the TLC plate
If the madder or turmeric is not already in solution, dissolve about 1 mg in 1 mL of a volatile solvent such as hexanes, ethyl acetate, methylene chloride or ethanol. As a rule of thumb, a concentration of 1% usually works well for TLC analysis. If the sample is too concentrated, it will run as a smear or streak; if it is not concentrated enough, you will see nothing on the plate.
To obtain a micro capillary on TLC plate we need small dot on TLC plate. In the labs, we make Pasteur pipettes. Dip the Pasteur pipettes into the solution and then gently touch the end of it onto the proper location on the TLC plate. Shouldn’t allow the spot to become too large - if necessary, we could touch it to the plate, lift it off and blow on the spot. If we repeated these steps, the wet area on the plate will stay small.
Step 4: Develop the plate
Placed the prepared TLC plate in the developing beaker, covered the beaker with the watch glass, and leave it undisturbed place. The solvent will rise up the TLC plate by capillary action. Make sure the solvent does not cover the spot.
Allow the plate to develop until the solvent is about half a centimeter below the top of the plate.
Figure 7: Prepare the TLC plate (2) (courtesy: orgchem.colorado.edu)
Figure 8: Turmeric Solution (courtesy: orgchem.colorado.edu)
Figure 9: Pasteur pipettes dipped in solution (courtesy: orgchem.colorado.edu)
Figure 10: Develop the TLC (courtesy: orgchem.colorado.edu)

4. Removed the plate from the beaker and immediately mark the solvent front with a pencil. Allow the plate to dry.
Step 5: Visualize the spots
If there are any colored spots, circle them lightly with a pencil. If the TLC plate runs samples which are too concentrated, the spots will be streaked and/or run together. If this happens, we would have to start over with a more dilute sample to spot and run on a TLC plate.
Step 6: Calculating Rf
Now we were measuring the distance traveled by the madder or turmeric on mobile phase and distance traveled by the solvent front on stationary phase of TLC plate for calculating the retention factor of madder or turmeric. And put that value in required equation which is describe in introduction.
Our Lab Sample:
Figure 11: Visualize the spots (courtesy: orgchem.colorado.edu)
Figure 12: Image of Lab Sample for testing madder & turmeric Rf

5. Conclusion: This test is very important for dyeing because to find out the new color of chemical by testing on TLC plate. In this experiment the madder have lower Rf factor then Turmeric which is better for dyeing then turmeric dyeing. So this experiment also important for comparing the color fastness of material. At last we say that this experiment is very important for basic acknowledgement of TLC method, Rf for Dyeing.
Reference:
 www.wikipedia.com
 www.google.com
 www.orgchem.colorado.edu
 www.gxnu.edu.cn