Nicole Jaffrezic‐Renault

Caffeine is a central nervous system (CNS) stimulant and is the most routinely used drug in the world. It is present in coffee, tea, in soft drinks. It is responsible for bitterness in coffee and tea. A new microconductometric sensor for the detection of caffeine was designed, based on a PVC liquid membrane including a [ o ‐COSAN] − /caffeine ion‐pair complex deposited on interdigitated electrodes. This caffeine sensor presents de dynamic range from 10 −6 M to 10 −1 M and a limit of detection of 0.3 μM. The sensor presents good reproducibility (RSD 3 %) and repeatability (RSD 8 %). The shelf‐life time of the sensor was more than three months. The sensor is selective versus interfering components present in the different matrices (coke, tea, and coffee) and was used successfully for the detection of caffeine in these matrices.