Chem 3AL - Lab Report #7

Chem 3AL - Lab Report #7 - Kylie 21 July 2010 Chem 3A Lab...

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Kylie 21 July 2010 Chem 3A Lab Experiment #8 Discussion: TLC Plate 4 was developed with all four given samples (#81-84), which included the adulterated one (#84) and the three pure samples. Cospotting the four H/S compounds would allow direct comparison of their Rf values, appearances under the UV lamp, and other characteristics under different visualization methods. The results from my system (90% hexane and 10% ethyl acetate, UV, I 2 ) showed that #81 and #84 were almost identical in terms of the shade and size of their UV spots, their UV/I 2 Rf values, and their I 2 stains. #82 and #83 had significantly lower UV/I 2 Rf values and didn't match with #84 in any other way, so #81 (anise) was determined to be one of the compounds mixed in #84. The next step was to identify the adulterant mixed with anise, so TLC Plate 5 was developed with #81, #84, and #821 (another group's hexane extract which my group chose based on its appearance and smell that matched the adulterated sample's). The results of this last plate showed that #84 once again matched nicely with #81, and that it also had another set of small UV and I 2 stains (which I disregarded before) that matched nicely with #821's stains. Both #84 and #821 had a small UV spot with an I 2 stain right below it, and their Rf values matched; as a result, it was confirmed that anise (#81) was mixed with the adulterant cinnamon (#821) to form our adulterated sample. Furthermore, my results were confirmed by other group members who used different solvent systems and visualization methods, including DNPH analysis. The first step towards identifying the adulterant was to observe the three possible H/S samples that it could be mixed with, as well as the adulterated sample. After recording their physical appearances and odors, they were put aside in hexane for later TLC analysis. The next step was
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