Determination of Caffeine in Lindt’s Dark and Milk Chocolate. Sarah Bassett; Stefanie Gibson; Abigail Joyce. Oregon State University, Department of Chemistry.  2005.

Abstract:

This experiment was conducted to find and compare the amount of caffeine in milk and dark chocolate. Lipids were extracted from chocolate samples using petroleum ether washes. A sample of known caffeine concentration also underwent this treatment. The resulting solutions were tested for caffeine using reverse phase HPLC. Caffeine concentration was determined using external calibration methods. The known caffeine sample yielded a 31% recovery. The average amount and RSD of caffeine in the dark and milk chocolate was 6.87.10³+6.4% ppm and 2.04x10³+34% ppm, respectively. Based upon recovery results the calculated amount of caffeine in dark and milk chocolate should be 2.18x10⁴+6.4% ppm and 6.47x10³+334% ppm, respectively.