Characterization of aqueous solution of cresol red as food irradiation dosimeter

Dilute aqueous solution of cresol red has been evaluated spectrophotometrically as possible gamma rays dosimeter. A 0.10 mM solution of cresol red was irradiated by gamma rays using a cobalt-60 radiation source. The absorbance spectra of the unirradiated and irradiated solutions were recorded using double beam scanning spectrophotometer. The absorbance of the solution before and after irradiation was measured at 434 nm (lambda(max)) as well as at other wavelengths (415, 448 and 470 nm). Various parameters, such as Absorbance (A), Delta A, %A, -log A and log A(o)/A(i) were plotted against radiation dose, in order to check the response of cresol red solution and its possible use as chemical dosimeter. The response plots of A, Delta A, and %A versus absorbed dose showed that the solution can be used as a radiation dosimeter in a dose range up to 0.82 kGy. Using response plots of -log A and log A(o)/A(i), the useful dose range can be extended up to 1.65 kGy; which are useful dose ranges for food irradiation applications. Stability studies of cresol red solution at different light and temperature conditions for pre- and post-irradiated storage of the dosimetric solutions suggested that aqueous solution of cresol red is highly stable in dark, under fluorescence light and at room temperature up to 150 days.