A-level set practicals: TLC of plant photosynthetic pigments

This resource, from SAPS, supports the use of practicals across 2015 A-level biology specifications.

Students conduct Thin Layer Chromatography (TLC) individually or in pairs to separate and identify the photosynthetic pigments from plant material within half an hour. This simple method has been designed to produce good separation of photosynthetic pigments using solvents that are suitable for use in a school biology laboratory. By using grass from a school lawn or playing field, students can see the variety of different molecules that can be separated from a plant that they are all very familiar with.

These resources and this practical allow students to develop their understanding of photosynthetic pigments and how chromatography separates molecules. By taking simple distance measurements from the chromatogram for calculating Rf values, this practical provides a good opportunity to introduce the concept of percentage error. It provides students with the opportunity to develop (and demonstrate) their skills of taking quantitative measurements as well as their ability to consider variables that need to be controlled.

Materials include:

• Tested materials to support the A-level practical endorsement (CPAC)
• Support materials for teachers and technicians
• Student worksheet to help provide evidence for meeting the practical skills requirements
• Student revision materials to help prepare for exams