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Title:   Author  item
                                            ORTEGA SANTIAGO, JORGE - University Of Puerto Ricoitem
                                            Appell, Michaelitem
                                            Wang, Lijuanitem
                                            ORELLANA, LYNETTE - University Of Puerto Rico
  Submitted to: Meeting Abstract
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 7/19/2016
                                    Publication  Date: 7/19/2016
                                    Citation: Ortega Santiago, J., Appell, M.D., Wang, L.C., Orellana, L.E. 2016. Effect of pH and solvent on the fluorescence spectroscopy of ochratoxin A [abstract].Interpretive Summary:
                                Technical Abstract: Ochratoxin A is a potential contaminant of agricultural commodities that is produced by Aspergillus and Penicillium species. Although this toxin has been observed at very low levels in commodities, it can reach levels of concern under certain conditions. It exhibits deleterious effects on animals and in vitro cell-based toxicity studies, and is associated with nephrotoxicity, carcinogenicity, hepatotoxicity, and immunotoxicity. This toxin can be found in a variety of foods and beverages, including wines and coffee. Several commercial and laboratory based methods to detect ochratoxin A exist, and many rely on the native fluorescence of this toxin for accurate quantitation. However, food matrix can have a significant effect on the detection properties of analytes. A comprehensive study was carried out on the influence of solvent, pH, and intermolecular interactions on ochratoxin A fluorescence to gauge the impact on detection. Steady state fluorescence spectroscopy studies of ochratoxin A in aqueous solutions between pH 2-10 indicated a complex relationship between fluorescence intensity and emission wavelength. The results suggest fluorescence of ochratoxin A is influenced by the intramolecular hydrogen bonding schemes associated with the phenylalanine and dihydroisocoumarin moieties, and the anionic and dianionic forms of ochratoxin A exhibit a complex relationship with emission. Fluorescence emission maximum intensity varied between 445 to 475 nm in polar protic and aprotic solvents depending on solvent type at the excitation wavelength of 333 nm. In summary, the results presented in this study suggest the microenvironment of ochratoxin A influences the fluorescence properties and should be a consideration in the development of new fluorescence based detection methods.


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