Feasibility of Using Luminescence Spectroscopy for Analyzing Phthalates Upon Their Conversion into Fluorescein

The feasibility of using the conversion of phthalates to fluorescein in analytical luminescence spectroscopy for the detection of phthalates is considered. Phthalates are converted to fluorescein by their prior hydrolysis to give phthalic acid followed by dehydration of this acid to give phthalic anhydride and the reaction of the latter with resorcinol. The formation of luminescent byproducts in the autocondensation of resorcinol molecules presumably with the products of their own oxidation and decomposition was detected. The luminescence spectrum of the by product mixture obtained upon the transformation of resorcinol overlaps the spectrum of fluorescein and the relative quantum yield of the mixture luminescence was 25%. This behavior hinders the use of this reaction for analytical purposes since special care is required for sample preparation and selection of the reaction conditions in order to minimize or, hopefully, eliminate the formation of such luminescent by products.