The various pigments in chloroplast pigments have different chemical structures, and thus their physicochemical properties such as polarity, absorption spectra, solubility, etc. are also different. Chlorophyll and carotenoids are ester compounds, insoluble in water and soluble only in non-polar solvents such as alkanes, petroleum ethers, etc., which can be used to separate the chloroplast pigments by using the distribution coefficients of the different pigments in various organic solvents as well as the differences in the degree of adsorption on the adsorbent.

Operation method

Experiments on the separation of chloroplast pigments by paper chromatography

Principle

The various pigments in chloroplast pigments have different chemical structures, and thus their physicochemical properties such as polarity, absorption spectra, solubility, etc. are also different. Chlorophyll and carotenoids are ester compounds, insoluble in water and soluble only in non-polar solvents such as alkanes, petroleum ethers, etc., which can be used to separate the chloroplast pigments by using the distribution coefficients of the different pigments in various organic solvents as well as the differences in the degree of adsorption on the adsorbent.

Materials and Instruments

Filter paper for chromatographic analysis Petri dishes Short glass tubes Gasoline Benzene Concentrated chloroplast pigment extracts

Move

Take a piece of color layer analysis filter paper, cut it into a square, its side length is slightly larger than the diameter of the petri dish, and make a small round hole in its center. Another take a small strip of analysis filter paper, thick chloroplast pigment extraction solution coated in a long side of the filter paper strip, and make the coated color band as narrow as possible, so that air-drying; four or five consecutive coated, to be air-drying after the filter paper strip will be rolled into a two-centimeter twist of paper, and the point of the sample end inserted into the center of the square filter paper as a "lamp center".

Take a large petri dish, in which a short glass tube, the tube contains a small amount of gasoline about 1/2 to 2/3 of the volume of the glass tube, add one or two drops of benzene. Insert the "lamp center" prepared in the above way into the small glass tube, cover the petri dish and place it in low light or in a dark place.

Made of filter paper "lamp heart" by capillary action to absorb the solvent, dissolved in the solvent in the pigment and then diffuse around, 10-20 minutes after the pigment concentric ring can be obtained in different colors: chlorophyll a blue-green, chlorophyll b is yellow-green, lutein is bright yellow, carotene is orange-yellow. The color of chlorophyll a is blue-green, chlorophyll b is yellow-green, lutein is bright yellow, and carotene is orange.

Indicate the name of the pigment type on the finished color ring filter paper sheet and attach it to the lab report.

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