Purpose: The purpose of this experiment is to identify the brand name of an unknown commercial analgesic product by TLC analysis. Unknown #1 solution was run against standard solutions of individual analgesics. The components of the unknown product were identified by comparing characteristic traits, such as Rf, fluorescence and iodine staining, to those exhibited by the standards. The name of the commercial product was then determined using the reference table, Analgesics & Caffeine in Some Common Preparations. Reactions: Procedure: Refer to Pavia, et. al. , Introduction to Organic Laboratory Techniques; 4th ed.
, Thomson Learning, pp. 82-86 Procedure Modifications: In the Initial Preparations steps we used capillary tubes rather than preparing capillary micropipets to spot the plates. We used 5cm x 20cm TLC plates instead of 6cm x 10cm plates; this required a different slide layout. Also, only 4 samples were spotted on each plate rather than 6. We analyzed 1 unknown commercial product on plate two. All standards were spotted twice and the reference samples as well as unknown were spotted six times.
In the Preparing the Development Chamber steps we used large developing chambers which we shared with a partner rather than using the 16-oz.wide mouth jars. The Analysis of Commercial Analgesics or Unknowns steps were omitted since we included an unknown on our second plate. Observations and Data: Total TLC development time was 50 minutes. Table 1: TLC Data for Standard Analgesics, Reference Mix & Unknown Components* Standard Substance| Distance Spot Travels (cm)| Distance Solvent Front Travels (cm)| Fluorescence? | I2 Staining Appearance| Acetaminophen| 48| 150| No| Dark Yellow| Aspirin| 86| 150| No| Not Significant| Caffeine| 14| 150| No| Not Significant| Ibuprofen| 92| 148| No| Not Significant|.
Salicylamide| 81| 148| Yes| Yellow| | | | | | Reference Mix:| | | | | Spot 1^1/1^2| 14/14| 150/148| No/No| Not Significant| Spot 2^1/2^2| 44/46| 150/148| No/No| Dark Yellow| Spot 3^1/3^2| 77/77| 150/148| Yes/Yes| Yellow| Spot 4^1/4^2| 89/90| 150/148| No/No| Not Significant| | | | | | Unknown:| | | | | Spot 1| 15| 148| No| Not Significant| Spot 2| 85| 148| No| Not Significant| Notes: *See developed TLC plates 1 &2, attached. 1. From Plate #1 2. From Plate #2 Calculations: Example: Rf= Distance spot travels/ Distance solvent front travels Rf of Acetaminophen= 48cm/ 150cm.
Rf of Acetaminophen= 0. 320 Results: Table 2: Rf and Identification of TLC Spot Substance| Rf(s)| Spot ID| Acetaminophen| 0. 320| N/A| Aspirin| 0. 573| N/A| Caffeine| 0. 093| N/A| Ibuprofen| 0. 622| N/A| Salicylamide| 0. 547| N/A| Reference Mix:| | | Spot 1^1/1^2| 0. 094 Avg. | Caffeine| Spot 2^1/2^2| 0. 302 Avg. | Acetaminophen| Spot 3^1/3^2| 0. 517 Avg. | Salicylamide| Spot 4^1/4^2| 0. 601 Avg. | Ibuprofen| Unknown #1:| | | Spot 1| 0. 101| Caffeine| Spot 2| 0. 574| Aspirin| Unknown #1 Commercial Product Name: Anacin or Cope (Both contain Aspirin and Caffeine) Conclusion:
The Identity of unknown #1 is either Anacin or Cope because the spot locations on the plates when compared to the known analgesics as well as the reference samples indicate the presence of aspirin and caffeine. Also, the Rf values of the unknown spots indicate the presence of aspirin and caffeine when compared to the Rf of the known analgesics and reference samples. Neither spot in the unknown sample showed fluorescence or significant iodine staining, eliminating salicylamide and acetaminophen as possibilities. After using the chart on page 69 of the text as a reference I was able to determine that the unknown was either Anacin or Cope.