Fig. 4.

Chromatographic and mass spectrometric analyses of Barraca Brown bottle (sample 4DK-136). (A) LC-MS chromatogram. Black, total-ion chromatogram; red, selected-ion monitoring (SIM) at m/z = 181 for theobromine; blue, SIM at m/z = 195 for caffeine. For the mass spectrum of the peak at 3.0 min, as well as details of methods and standards, see SI. (B) UV chromatogram of the same extract, showing a peak at 3.0 min, which is consistent with results in a. Dashed lines are integration markers; arrows indicate the starts and ends of peaks. The peak at ≈2.1 min in the UV is due to the chromatography solvent.