Fluorescein sodium salt is a disodium salt of fluorescein and a noted pH sensitive fluorophore. Fluorescein sodium salt has been utilized in studies as a drug model, as a penetrating dye and also as a fluorescein tracer. Fluorescein sodium salt has also been used in vitro to quantify root dentin demineralization. Additional reported uses include microscopy, as a gain medium in dye laser use and to detect latent blood stains. Common derivatives of Fluorescein include fluorescein isothiocyanate (FITC), eosin and Rose Bengal (sc-296278) and Rose Bengal sodium salt (sc-203757)