How much caffeine is in your coffee?

The amount of caffeine in various beverages can vary widely. Drip-brewed regular coffee has about 555–845 mg/L caffeine content but a shot of espresso can have about 1,691–2,254 mg/L. What some people may not know is that decaffeinated coffee has caffeine as well. The caffeine is chemically removed by a series of extraction procedures (solvents used can include benzene, supercritical CO₂, or others). However, even after 8–12 extractions there is still some caffeine remaining. Therefore, decaffeinated coffee has about 24–72 mg/L caffeine.
                This can be studied with HPLC methodology. Here a Cogent Bidentate C18 2.o™ column is used to separate caffeine from other matrix components in three types of common coffee products. The caffeine peak is the most prominent of all the peaks in the espresso sample but is only a minor peak with the decaf sample. Using a caffeine reference standard, a calibration curve could be made which allows for an estimation of the caffeine content in the samples. The calculated values were: espresso: 964 mg/L, regular: 539 mg/L, and decaf: 85 mg/L. These values were mostly close to the literature ranges for each coffee beverage, although the espresso sample had somewhat lower caffeine content than expected.
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