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IIT/FIELD MUSEUM—High School Transformation Project
Biology
D! "!T #$ITE !" THIS% THIS IS THE &L'SS &L'SS &!P( !F THE L'B% La)* Using Pa+er &hromatogra+hy to Se+arate Pigments B'&,-$!U"D* The leaves of most plants contain many dierent pigments. Chlorophyll is the most abundant and important plant plant pigment for absorbing absorbing sunlight. It exists in two forms: chlorophyll a (bright (bright green) and chlorophyl chlorophylll b (dull (dull green). green). Chlorophyll often hides the other pigments pigments present in leaves. In autumn chlorophyl chlorophylll levels drop drop allowing allowing other pigments pigments to show their colors. !ellow ellow xanthophyll xanthophyll and orange carotene carotene are commonly visible at this this time. "ther pigments may also be be present in leaves. .estion* #hat is the purpose of pigment$
P'USE "!# '"D '"S#E$ THIS .UESTI!" !" (!U$ L'B $EP!$T $EP! $T%% The individual pigments in a leaf may be separated by the techni%ue of paper chromato chromatograph graphy. y. Chromato Chromatograph graphy y means means &color &color writing'. writing'. The separa separation tion taes taes place by absorption absorption and capillarity. The paper absorbs absorbs the mixture of pigments in a solvent. solvent. Capillari Capillarity ty pulls the substances substances up the paper paper at dierent dierent rates depending depending upon their specic properties. properties. *s a result the pigments will separate separate on the paper. paper. They show up as colored streas. The pattern of separated pigment colors on the paper is called a chromatogram.
PU$P!SE* !ou !ou are a plant specialist woring for a natural clothing company. company. *ll the garments manufactured by your company are made from natural plant bers and are dyed with natural natural dyes. "ne of your company+s company+s designers designers wants you to develop develop a new yellow dye. !ou thin one of the plant species growing growing in the company greenhouse contains contains yel yellow low pigme igment nt.. !ou deci ecide to sep separa arate the the lea leaf pigm pigme ents nts usi using pape paperr chromatography. M'TE$I'LS* ,pinach leaf solution Chromatography paper strip - m/ beaer ,olvent0 *cetone or isopropyl alcohol approximately approximately - m/ 1uler 2encil ,cissors Tape Tape
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IIT/FIELD MUSEUM—High School Transformation Project
Biology
D! "!T #$ITE !" THIS% THIS IS THE &L'SS &!P( !F THE L'B% P$!&EDU$E* 2art - 2reparing the Chromatogram. *) ;raw a line in pencil across the paper -.< cm from the bottom. =) ,tarting at the line taper the bottom of the paper with scissors. C) !our chromatogram should resemble >igure *.
Figure A Chromatogram
2art 6 *dding the pigment. *) ?sing the disposable pipette place -06 drops of the spinach solution on the pencil line. =) *llow the drop to dry. Pencil line
Place drops on pencil line and allow to dry. 2art 7 1unning the experiment. *) ?ncover the beaer. ;" @"T I@3*/A T3A ,"/BA@T =) 2lace the lter strip into the beaer so that only the tip soas in the solvent. C) >old the top of the paper over the edge of the beaer. =e sure the paper doesnDt sin further into the solvent. The green drop C*@@"T be in the solvent. C) #ait fteen minutes or until the pigments fully separate. There should be dierent colors of pigment visible on the strip. A) 1emove the lter strip and cover the beaer with plastic wrap. >) ,etch your pigment bands in your lab report on the outline you made earlier. 5) 1ecord the colors in T*=/A -. 2art E Identifying the pigments. *) ?se the information below to identify which pigments are in your leaf: Chlorophyll a: bright green0yellow Chlorophyll b: dull blue0green or hai Carotene: orange or gold Fanthophyll: pale yellow =) 1ecord your pigment names in T*=/A -. C) /abel the pigment names on your setch in your lab report.
6 0 C 3 1 " 4 * T " 5 1 * 2 3 !
C"3"1T
-67
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IIT/FIELD MUSEUM—High School Transformation Project
