Chemistry 123 Lab 10 Abstract The caffeine content was determined in the carbonated drinks: Pepsi, Pepsi one, Coke, Diet-coke, Jolt. By separating crude caffeine through extraction in a separatory funnel, filtering the extrac extractio tion, n, evapora evaporatin ting g the solvent solvent,, and purify purifying ing using using vacuum vacuum sublima sublimatio tion, n, it was determined that Pepsi –one contains the most caffeine. Introduction Caffeine is one of the world’s most widely used “drug” that has been subtly added to soft drinks for the primary source of flavour (Hirsch et al. 2007). Caffeine enhances wakefulness, alertness, concentration, and energy however it raises health concerns such as decreased reaction time, caffeine- induced headaches, and interrupted sleep to name the few (McCusker et al. 2006). It was found that 86% of soft drink consumers could not detect the difference in flavour between soda samples high in caffeine versus low in caffeine (Hirsch et al. 2007). Methods of extracting caffei caffeine ne includ includee isocra isocratic tic revers reversee- phase phase liquid liquid chroma chromatog tograph raphy y and annular annular centrif centrifugal ugal contractors. The melting point of caffeine is 236.1 degrees and the boiling point of dichloromethane is 39.8 degrees (CRC Handbook of Chemistry and Physics). For this experiment, dichloromethane, CH2Cl2, was used as the solvent. Because of its low boiling point as well as the solubility of caffeine in dichloromethane, CH2Cl2 was an excellent solvent. The different solubility produced two two immi immisc scib ible le laye layers rs of liqu liquid id ma maki king ng the the caff caffei eine ne much much easi easier er to sepa separa rate te as the the dichloromet dichloromethane hane was later evaporated evaporated to extract extract crude caffeine. caffeine. The caffeine caffeine content in several several cola drinks was determined through liquid- liquid extraction, solvent removal via evaporation then purified by vacuum sublimation, in order to compare the caffeine content in each beverage. Experimental Section Refer to experimental design form Results Drink Amou Amount nt
Coke of 46.0
Diet Coke 176.0
Pepsi 8 8.0
Pepsi-one 302.0
Jolt 390.0
crude caffeine (mg/L)
Melting Point °C
Crude Caffeine 234.1-236.9
Purified Caffeine 234.9-236.8
Discussion According According to the data table above, Jolt contains contains the most caffeine caffeine compared to the other four carbonated beverages. Coke contains the least amount of caffeine with only 46.0mg/L, Pepsi only has 88.0mg/L and Diet coke has 176.0mg/L. For this set of data, Pepsi- one contains 302.0mg/L and jolt contains 390mg/L, making it the most caffeinated drink. However, when comparing it with the overall class data, it was found that, for some groups, Pepsi-one contained the most caffeine. In every experiment, it is very difficult to be free of error. When draining the lower organic solvent, dichloromethane with caffeine, from the separatory funnel, an exact extraction was not made due to observation error. In order to drain only the lower solvent and not allow the interphase bubble layer out, not all of the dichloromethane and caffeine was drained. In addition, when pouring the organic solvent into the filter paper, some of the content could have escaped and may have not been fully fully draine drained. d.
Also, Also, when determin determining ing the melting melting point for each
caffeine sample, because this is also based on observation, one’s perception of melting could be different from another resulting in different values. In order to obtain more accurate results, more tests could have been performed on each specific carbonated drink and an average of the results could have been used. Also highperformance liquid chromatography could have limited the human error/ mistakes that occurred during the extraction process. Using Using the Digime Digimelt, lt, the meltin melting g point point of crude crude caffei caffeine ne was determ determined ined as 234.1234.1236.9°C. This corresponds to the melting point of caffeine, 236.1(0.2) °C found in the CRC
handoo!. Conclusion My initial hypothesis has a clear correlation and is supported by the results attained from the experiment. As predicted, coke contains the least amount of caffeine and Jolt has the most caffeine.
Bibliography Hirsch, A.R.; H.H.; Ma, A. Health Effects of Caffeine in Commercial Cola Beverages. Alternative and Complementary Therapies. 2007. 13, 298-303. Mccusker, R.R.; Goldberger, B.A.; E.J. Caffeine content of Energy Drinks, Carbonated Sodas, and Other Beverages. Journal of Analytical Toxicology. 2006, 30, 112-114.
