Lllk, Lmk
EXPERIMENT 8 THIN LAYER CHROMATOGRAPHY AND MELTING POINT DETERMINATION: DETECTION OF CAFFEINE IN VARIOUS SAMPLES
Additional Resources http://orgchem.colorado.edu/hndbksupport/TLC/TLC.html http://coffeefaq.com/caffaq.html Materials Needed TLC equipment: 1 5-cm x 8-cm TLC plate, 2 capillary micropipettes, TLC tank and lid, ruler, UV lamp Extraction Equipment: spatula, 2 small test tubes, Pasteur pipet and bulb Chemicals: caffeine, ethanol, dichloromethane, TLC solvent (5% acetic acid in ethyl acetate) Meltemp apparatus and capillary tube Three of the following samples for analysis: diet cola, diet lemon-lime soda, analgesic pill, instant coffee, instant iced tea Purpose In this experiment, thin-layer chromatography (TLC), a standard technique for the qualitative analysis of mixtures, will be introduced. First, a sample of caffeine will be authenticated by measuring its melting point. The authentic caffeine will then be used as a standard for the TLC analysis one of the following items: a diet soda, tealeaves, instant coffee, cocoa powder, or an analgesic pill. The caffeine present in these substances must first be separated from dissimilar materials in the substance using a process called extraction. Extraction simply involves treating the substance with an organic solvent that will dissolve out the caffeine and other soluble organic materials but leave insoluble matter (such as cellulose in leaves and inorganic binders in a pill) behind. Background Caffeine. Caffeine is a heterocyclic (i.e., has atoms other than carbon in a ring) amine found in many plant materials including tealeaves, coffee beans, kola nuts, cocoa beans, and guarana seeds. Compounds found in nature are referred to as “natural products” and amine natural products are called alkaloids. Hence, caffeine is an alkaloid. Many alkaloids, including caffeine, have pharmacological effects. Some other examples are morphine, codeine, cocaine, and nicotine. Caffeine-containing beverages, mainly tea and
Additional Resources http://orgchem.colorado.edu/hndbksupport/TLC/TLC.html http://coffeefaq.com/caffaq.html Materials Needed TLC equipment: 1 5-cm x 8-cm TLC plate, 2 capillary micropipettes, TLC tank and lid, ruler, UV lamp Extraction Equipment: spatula, 2 small test tubes, Pasteur pipet and bulb Chemicals: caffeine, ethanol, dichloromethane, TLC solvent (5% acetic acid in ethyl acetate) Meltemp apparatus and capillary tube Three of the following samples for analysis: diet cola, diet lemon-lime soda, analgesic pill, instant coffee, instant iced tea Purpose In this experiment, thin-layer chromatography (TLC), a standard technique for the qualitative analysis of mixtures, will be introduced. First, a sample of caffeine will be authenticated by measuring its melting point. The authentic caffeine will then be used as a standard for the TLC analysis one of the following items: a diet soda, tealeaves, instant coffee, cocoa powder, or an analgesic pill. The caffeine present in these substances must first be separated from dissimilar materials in the substance using a process called extraction. Extraction simply involves treating the substance with an organic solvent that will dissolve out the caffeine and other soluble organic materials but leave insoluble matter (such as cellulose in leaves and inorganic binders in a pill) behind. Background Caffeine. Caffeine is a heterocyclic (i.e., has atoms other than carbon in a ring) amine found in many plant materials including tealeaves, coffee beans, kola nuts, cocoa beans, and guarana seeds. Compounds found in nature are referred to as “natural products” and amine natural products are called alkaloids. Hence, caffeine is an alkaloid. Many alkaloids, including caffeine, have pharmacological effects. Some other examples are morphine, codeine, cocaine, and nicotine. Caffeine-containing beverages, mainly tea and