Photophysics of Ochratoxin A in Aqueous Solution

The photophysics of Ochratoxin A (OTA) in aqueous solution strongly depends on the pH. Due to its molecular structure OTA is prone to an excited state proton transfer reaction, which rules the photophysical properties. Based on results of absorption and fluorescence measurements the rate constants of the proton transfer reactions (forward and back reaction) were determined and subsequently, the pK value was calculated. Based on the results, optimized experimental conditions for the analysis can be determined e. solvent conditions (HPLC chromatography) or excitation and emission wavelength (fluorescence spectroscopy).