Identifying pigments in spinach and red leaves using chromatography
Abstract
Inside----. Purpose of this lab was to identify the pigments in spinach and red leaves that make up their color. To do this an extract from the plants is added to a strip of chromatography paper and put into a solvent (10% acetone, 90% petroleum ether). The solvent gets sucked up and draws the extract with it. This action leaves different colored marks on the paper strip. Pigments found in spinach and red leaves has different solubility. Using Rf value we can identify each pigment. Errors that may occur is spill of plant extract on the chromatography paper when using a pipette, fine capillary tubes is recommended.
Introduction
Chloroplasts, small, green, well-defined bodies (plastids) in the protoplasts of the cells in many photosynthetic organisms. (Cooper, 2000) The color is due to chlorophyll content, but they also contain yellow, orange or red carotenoids. Inside the chloroplast there is a network of membranes, tylakoid membranes, which contain pigments (chlorophyll a and b and carotenoids (carotene and xanthophyll)), as well as electron and prototransmitters that participate in photosynthesis light reaction. These are organized into two photosystems, photosystem II, where the water cleavage occurs, and oxygen is excreted, as well as photosystems in which NADPH2 is formed. Chromatography is exploited that the substances are of different solubility. Leaving an organic solvent pull up in a paper, the compounds that are readily soluble in the solvent used is coated with this, while the substances that are less soluble will be the same location in the paper or only a moving a bit. A bit of the sample to be analyzed is placed on chromatography paper, which is then immersed in a solvent. The solvent would then be sucked up, pass the stain and the solute drag with them, depending on where the substance is soluble in the solvent (Woodford, 2009).
The purpose of this lab was to separate compounds in spinach to see what pigments there is in spinach. If chromatography paper with spinach extract on it is put into a solution of petroleum ether, then we can see different pigments appearing on the paper. The prediction here is that spinach will have green and yellow pigments.
The purpose of the other lab where we used red leaves instead of spinach is to see what pigments red leaves has. If red leaf extract on a chromatography paper it is put into a solution of petroleum ether, then we can see different pigments appearing on the paper. The prediction here is that red leaves have red and yellow pigments.
Observation and result
When spinach extract was added to the chromatography paper and dipped down in the petroleum ether solution we could see that the paper sucked the solvent (10% acetone-90%petroleum ether) up. The solution got soaked up by the paper and when it reached the spinach extract it transported it upwards. After about 5 minutes the paper was soaked all the way up and...
