***Warning: Experiments involve harmful hazardous chemicals. DO NOT CONDUCT EXPERIMENTS AT HOME!
Experimental procedure(s)
- Experiment #01: The procedure followed a procedure taught in Organic chemistry lab. Caffeine was extracted from coffee by hot water first, then filtration and liquid-liquid extraction with chloroform was performed to get caffeine to chloroform phase. The organic phase (chloroform) was then dried with magnesium sulfate (MgSO4) and solvent was removed by heating at mild temperature. The sublimation was applied on the paste to collect caffeine crystals.
- Experiment #02: The procedure started with brewing coffee in hot water first, then filtration was applied and the filtrate was added to acetone. Solvent was then removed by mild heating. The sublimation was applied on the paste to collect caffeine crystals.
- Experiment #03: The procedure started with brewing coffee in hot chloroform, then filtration was applied. Solvent was then removed by mild heating. The sublimation was applied on the paste to collect caffeine crystals.
| Main experiment factors | Exp #01 | Exp #02 | Exp #03 |
|---|---|---|---|
| Mass of coffee (grams) | 3.3938 | 3.0519 | 3.5797 |
| Mass of calcium carbonate (CaCO3, grams) | 1.0440 | 1.0112 | 0.9696 |
| Solvent for brewing | Water | Water | Chloroform |
| Amount of solvent (mL) | 25 | 25 | 25 |
| Temperature of brewing (C) | 90 | 90 | 60 |
| Brewing time (minutes) | 30 | 40 | 40 |
| Additional solvent(s) used | Chloroform | Acetone | None |
| Sublimation temperature (C) | 200 | 200 | 200 |
| Sublimation time (hours) | 1.5 | 3.75 | 1.5 |
| Caffeine per grams of coffee (mg/g) | 6.25 | 4.46 | 21.65 |
Comments on the procedures and future experiments
- Calcium carbonate (CaCO3) was used during the extraction for precipitating out other carboxylic acids in the coffee.
- In Experiment #01, during the 2nd extraction with chloroform (CHCl3), emulsions formed so adding magnesium sulfate (MgSO4) helped breaking these emulsions (and thus, dry the organic phases).
- Because of high solubility of caffeine in chloroform and that the solvent is highly volatile, brewing with chloroform directly shortened the time of experiments and provided better yields.
- The experiment with chloroform seemed pretty good and needed to be repeated to make sure that the current result is reproducible. And that the procedure can be applied for future experiments (when I actually compared the caffeine in commercial coffee packs).
If you’re interested in these technical posts, like/subscribe/follow for similar contents. I will spare some times for the experiments as I’m super excited to see the results among coffee brands. And I welcome any further discussion from you all. Cheers!