Figure 7. Top: ECL-curves from different concentrated caffeine concentrations. Dashed line: ECL-curve from extracted caffeine. Red curve: without caffeine. Bottom: Calibration curve; the arrow shows the ECL-intensity of the coffee extract

From

Rapid and Sensitive Spectroelectrochemical Detection of Lidocainehydrochloride and Caffeine with Screen-Printed Electrodes

A. Habekost

World Journal of Chemical Education. 2016, 4(5), 107-113 doi:10.12691/wjce-4-5-3