Titanium dioxide was used as a photocatalyst to improve the yield and rate of product formation in a post-column derivatization reactor for microbore liquid chromatography. The photo-catalytic reactor demonstrated an increase in sensitivity of greater than one order of magnitude for the electrochemical detection of phenylalanine compared to the more typical open-tubular photolysis reactor. The detection limit for phenylalanine was also decreased by two orders using the photo-catalytic reactor.