Identification of an Adulterated Herb or Spice by TLC

Identification of an Adulterated Herb or Spice by TLC - Lab...

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Lab 8: Identification of an Adulterated Herb or Spice by Thin Layer Chromatography Discussion: 1. On plate 4, we analyzed samples 517, 518, 519, and 520. This TLC plate revealed that 520 (the adulterated compound) had an R f value similar to one of the spots for 517 (the R f value for 520 was 0.17; for 517, it was 0.12); each of the spots showed up in DNPH and under UV light when developed in 90:10 hexane:ethyl acetate. These results suggest that 517 (cinnamon) was present in 520, along with another substance. On plate 5, we co- spotted 523, 520, and 517 in 90:10 hexane:ethyl acetate, with 520 in the middle. The results showed that 523 and 520 both had two spots – each had one that showed up in DNPH with an R f value of 0.14, and one spot that showed in UV light with an R f value of 0.48. 517 had a spot that showed in UV light with an R f value of 0.48 as well. Based on these results, we concluded that 520 was a mixture of 523 and 517. 2. To determine what adulterant was present in 520, we qualitatively analyzed the mixture and noted its smell, texture, and appearance. Based on these aspects, we searched for a pure spice that had similar characteristics. 520 smelled similar to 517, which we were confident was cinnamon. 523 had the same consistency and some of the same color as 520, so I co-spotted the three herb/spice samples on a TLC plate in 90:10 hexane:ethyl acetate, and visualized it in either UV and DNPH. The spots matched up
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This note was uploaded on 04/12/2011 for the course CHEMISTRY 3AL taught by Professor Pedersen during the Fall '10 term at University of California, Berkeley.

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Identification of an Adulterated Herb or Spice by TLC - Lab...

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