Design of chemical sensor arrays that can discriminate real-world samples has been highly attractive in
recent years. Herein a fluorescent indicator-displacement sensor array for discrimination of fresh fruit
juices was developed. By coupling the unique high affinity of titania to electron-donating anions and
the cross-reactivity of molecularly imprinted materials to structurally similar species, a small array
was fabricated using only one rhodamine-based fluorescent dye and three synthesized materials. Citric,
malic, succinic and tartaric acids were chosen as indices. The recognition mechanism was investigated by
spectrofluorimetric titration using a non-linear Langmuir-type adsorption model. The proposed method
was applied to discriminate thirteen fruit juices through their carboxylic acid contents. Principal component
analysis of the data clearly grouped the thirteen juices with the first principal component owning
98.2% of the total variation. The comparison of the sensor array with HPLC determination of the carboxylic
acids was finally made.