PAPER CHROMATOGRAPHY LAB REPORT

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PAPER CHROMATOGRAPHY LAB REPORT

Introduction

Paper chromatography is a separation technique that utilize a solvents’ ability to carry with it a dissolved solute on a strip of absorbent material. It utilizes the principle of chromatography in which the mobile phase (solvent)carries the solute across the surface of a of an immobile phase (the cellulose on the paper) while depositing pigments of the solute on the rough surface of the paper.

Requirements

-Coffee paper

-Scissors

-4 Glasses of water

-Food colouring

-Pencil

-Ruler

-Toothpicks

Procedure

The coffee filter paper was folded into four strips of one-inch widths then cut along its length to come up with four paper strips. Each of the strips was then marked with a pencil leaving a one-inch allowance on both ends along its length and then impaled on one end with a toothpick. The strips were numbered 1 to 4. A drop of pigment was then dropped on the lower margin of the strip of paper with each strip getting one of the dyes. The strips were then suspended on the rim of the glass so that they were clear of the sides. Water was then added to the glass just so that the lower edge of the paper strip was touched. The experiment was then left to stand for 20 minutes then observed. The heights of the resulting strips and highest level reached by the water on the paper were measured by the ruler and tabulated on the table below. All heights are in centimetres.

Results

Spot colour Spot heihgt from origin Solvent height from origin Retention factor value

Food colour Red Red 3.30 cm 8.80cm 0.38

Pink 6.20 8.80cm 0.70

Green Yellow 6.80 8.80cm 0.77

Blue 4.00 8.80cm 0.45

Blue Blue 4.30 8.80cm 0.49

_ _ 8.80cm _

Yellow Yellow 6.60 8.80cm 0.75

_ _ 8.80cm _

The retention factor for the individual dye was then calculated by dividing the spot height and the solvent height and results tabulated.

Conclusions

The experiment was a success at determining the respective pigments within the four food colouring dyes. There was a corelation between similar pigments on different dyes and their retention factors a pointer to the fact that they might be similar in constitution.

Post lab questions

1 Types of chromatography

a. Liquid chromatography

b. Gas chromatography

2. What are the immiscible phasesThese are the components of the experiment that don’t get dissolved in the solvent, in the case of this experiment it was the cellulose on the paper.

3.Retention factors

A.32mm/74mm=0.432

B.59mm/74mm=0.797