Amperometric Photosensor Based on Acridine Orange/TiO 2 for Chlorogenic Acid Determination in Food Samples

The authors describe a novel sensor for chlorogenic acid (CGA) detection/quantification in food samples. The photosensor is based on a composite of titanium dioxide (TiO2) and acridine orange (AO). The synergism between AO and TiO2 was revealed under visible LED light irradiation by high photocurrents for CGA, when compared to each component of the composite material. A detection limit of 0.54 μmol L−1 and a linear response range from 2 to 200 μmol L−1 for CGA detection were achieved. The selectivity of the sensor was tested by using common interferents on samples containing chlorogenic acid and results suggested that there is no significant interference in the analyte response, indicating a good selectivity. Finally, the photosensor was successfully applied in the determination of CGA in samples of coffee, tea, and apple juice, with recoveries ranging from 100.9 to 102.4%, suggesting a good accuracy for the proposed method.