Applicability of activated carbon obtained from peach stone as an electrochemical sensor for detecting caffeine

Simple, economical and highly sensitive electrodes for the detection of caffeine by using activated carbon from peach stones have been developed. The activated carbons were synthesized by chemical activation using ZnCl2 and ZnCl2:FeCl3 (1:1) as chemical agents, producing carbons with different textural properties and morphologies, which led to differences in the electroactive area of the materials that affected the electrochemical response to caffeine. The electrodes presented a linear response in the concentration range from 3.98 × 10−5 to 4.58 × 10−4 and 6.37 × 10−4 M for the carbon activated with ZnCl2 and ZnCl2:FeCl3 (1:1), respectively. The detection limits were estimated in 2.85 × 10−5 and 1.60 × 10−5 M. The electrodes were tested to measure caffeine in real life samples, giving caffeine concentrations close to the reported values. Despite presenting the lowest surface area and the lowest thermal stability, the activated carbon obtained with ZnCl2:FeCl3 (1:1) was more sensitive to caffeine, measuring caffeine concentrations very close to the reported values for the tested beverages. These results show that these electrodes may be an alternative to develop new and reliable analytical tools at low cost with high efficiency.