Chromatography of Dyes

ABSTRACT

Separation and identification of components of a mixture was determined by using Chromatography. The components of a mixture have different affinities for a stationary phase as well as different affinities for a mobile phase.

INTRODUCTION

An extremely common technique by using two chemicals and filter paper can give you sufficient information. A well-done Chromatography of dyes will provide you with enough data to determine if a liquid mixture is heterogeneous or homogenous . In a learning activity you can separate and possibly identify food dyes in some drinks mixes and food colors. The effect of solvent polarity or the ability to separate and elute compounds will also be demonstrated. In this experiment you will need to use the equation Xcm/Acm=RF value. The length of A, is the length of the longest line of the food dye or food coloring. The Length of X is the length of all the other variables. In the experiment the lengths will be measured in Centimeters.

Experimental Procedure

You will need to obtain a piece of standard filter paper approximately 10*15 cm. Use a pencil to draw a line parallel to one of the longer edges, about 1 cm from the edge. Make 10 dashes on the pencil line, be sure to have them evenly distributed. At this point you will spot each of the 5 standards on separate dashes. Be sure to write down which liquid is at which dash. Then choose two food colors and two drink mixes, and spot them on the remaining four dashes. Curl the filter paper into a cylinder, make sure colors out, and staple the edges together. Do not allow the edges of the filter paper to overlap. Add approximately 10 ml of a 7:3 isopropanol:water mixture to your 600 mL beaker, then carefully place the chromatogram into the beaker the colored spots must be higher than the solvent. Be sure to cover the beaker, remove, lay out to dry then measure when the solvent is 1 to 2 cm from the top. Repeat all the above steps but use 0.1% NaCl in the place of the 7:3 isopropanol. By comparing the colors of the spots in the standards and the unknowns, and the distances the spots moved, you should be able to tell what compounds are present in the food colors and drink mixes. Some of the food colors and drink mixes may contain only one dye, and some may contain more than one. One solvent system may separate a mixture better than the

...