Lab 10 hand in - John Selman Nick Grover Nitisha Mitchell...

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John Selman Nick Grover Nitisha Mitchell 12/11/2009 Chromatography of Plant Pigments Introduction "Chromatography of Plant Pigments" is an experiment designed to introduce us to the nature of plant chemistry while taking Uv-vis spectrometer measurements of the pigments contained within the leaves. The first technique employed for the chomatography of the spinach pigment is silica-gel thin-layer chromatography (TLC). The TLC equipment is comprised of the stationary phase which is a thin layer of silica gel which is extremely polar and the mobile phase is acetone which is less polar, that allows the separate pigments to travel in height at different speeds to compute R(f) values, a comparison of the polarity levels of various spinach leaf pigment components. The second methodology of Uv-vis spectrometry employed is called silica-gel column chomatography where there exists a fine powder of silica gel that serves as the stationary phase in a small tube called a Pasteur Pipet. The other substances, the silicon powder, the petroleum ether, and the glass wool function together as a filter to remove the impurities of the spinach leaf pigment/acetone solution. The polarity of the material filtered is repelled by the silica gel, and becomes filtered by the glass wool and the silicon powder. What we are left with is a relatively clean and pure solution of spinach leaf pigment. Lastly, the return signal shown on the graphs produced by the Uv-vis spectrometer indicate the materials present in the leaves of the spinach. Procedures The procedures for Chromatography of Plant Pigments are straightforward albeit the fact that they are complicated. First, the Thin Layer Chromatography technique is employed using a silica gel plate, spinach leaves and a centrifuge as the main components. The spinach leaves are ground in a mortar and the liquid is extracted using a 5ml pipet and an 80-20 mixture of petroleum ether and acetone. Then once enough solution is extracted, it is transferred into a small test tube and is positioned into a centrifuge for two minutes. After the impurities have separated to the bottom of the test tube, a small drop of the clear fluid near the top of the test tube is extracted and positioned on the bottom of the thin-layer chomatography plate. When the drop of spinach leaf solution was dry, the plate was positioned into a small developing tank with approximately .5cm of the 80-20 petroleum ether and acetone mixture. Approximately 10
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This note was uploaded on 03/23/2010 for the course CHY CHY 123 taught by Professor Tisha during the Fall '09 term at University of Maine Orono .

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Lab 10 hand in - John Selman Nick Grover Nitisha Mitchell...

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