The focus of this study is to determine the degradation rates of cochineal dyes in different media due to exposure to UV light.  Controlled systems of only the dye in solution, with solvents representative of those used in paint, are used to directly probe the chemical breakdown the cochineal dye molecule.  Cochineal samples were irradiated with UVA and UVB sources, and monitored by absorbance spectroscopy throughout the irradiation. For aqueous samples, the average rate of disappearance under UVA irradiation was nearly 10 times that of UVB.   The photodegradation was also analyzed using reverse-phase HPLC with UV-Vis detection to separate photoproducts and quantify concentrations for kinetic analysis.  LC-MS was used to aid in the identification of photoproducts. Future work seeks to gauge the impact of additives used in food to stabilize cochineal dye in media relevant to art.  These studies can inform conservation methods and paint formulation to inhibit photodegradation.

Photo-degradation of Cochineal dye in oil-, alcohol- and aqueous media

247th National Meeting (2014)

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