Polymer modified glassy carbon electrode for the electrochemical determination of caffeine in coffee

4-Amino-3-hydroxynaphthalene sulfonic acid (AHNSA) was electropolymerized on a glassy carbon electrode. The deposited film showed electrocatalytic activity towards the oxidation of caffeine. The polymer-modified electrode showed high sensitivity, selectivity and stability in the determination of caffeine in coffee. The peak current increased linearly with the concentration of caffeine in the range of 6 x 10(-8) to 4 x 10(-5) mol L-1, with a detection limit of 1.37 x 10(-7) mol L-1 (LoD =3 delta/slope). Analysis of caffeine in coffee was affected neither by sample matrices nor by structurally similar compounds. Recoveries ranging between 93.75 +/- 2.32 and 100.75 +/- 3.32 were achieved from coffee extracts indicating the applicability of the developed method for real sample analyses. (C) 2012 Elsevier B.V. All rights reserved.