RP 7 Use of chromatography to investigate the pigments isolated from leaves of different plants, e.g. leaves from shade-tolerant and shade intolerant plants

Method

- Draw a straight pencil line about 1cm above the bottom of the filter paper.

- Grind a section of leaf with 20 drops of acetone in a mortar to release pigments.

- Use a capillary tube to apply pigment extract onto the center of the pencil line.

- Suspend paper in solvent, ensuring the liquid level does not exceed the pencil line. Allow solvent to run up paper.

- Remove paper from solvent and mark the solvent front with a pencil line.

- Calculate Rf values for each pigment spot (distance traveled by pigment/distance traveled by solvent).

Risk assessment

- Biohazard: Wash hands after use and seek assistance if needed.

- Chromatography solvent: Avoid contact, wear eye protection, keep solvent in fume cupboard, ensure good ventilation, and keep away from naked flame. Wash skin and eyes with cold water in case of contact.

- Acetone: Avoid contact, wear eye protection, ensure good ventilation, keep away from naked flame. Wash skin and eyes with cold water in case of contact

Conclusion

- Compare Rf values with known database values for pigment identification.

- Factors affecting mobility include affinity to paper and solubility. Pigments with lower affinities travel further, while more soluble pigments reach closer to the solvent front.

- Pigments with higher Rf values travel further up the paper

AA

AA