Stochastic Enantioselective Microsensors Used for Enantioanalysis of Limonene in Beverages

Enantioanalysis plays a very important role in different fields (e.g., health, pharmaceutics), including food sciences. (R)-limonene is responsible for the fragrance of the juice while the (S)-limonene’s flagrance does affect the test of beverages. Enantioanalysis, based on utilization of stochastic enantioselective microsensors designed using the immobilization of 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP) and of 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphyrin iron (III) chloride [Fe(TPFPP)]Cl in reduced graphene oxide decorated with Pd(0) and with gold nanoparticles, was performed to discriminate between the enantiomers S and R of limonene to determine racemization processes, and the source of the limonene. The signatures of the enantiomers are different when both microsensors were used, proving there enantioselectivity. The highest sensitivity for the assay of S-limonene was achieved by using the stochastic enantioselective microsensor based on [Fe(TPFPP)]Cl while the highest sensitivity for the assay of R-limonene was achieved when the stochastic enantioselective microsensor based on TPP was used. High reliability was achieved when the enantioanalysis of limonene was performed from different beverages.