Xanthenes: Compounds with three aromatic rings in linear arrangement with an OXYGEN in the center ring.Erythrosine: A tetraiodofluorescein used as a red coloring in some foods (cherries, fish), as a disclosure of DENTAL PLAQUE, and as a stain of some cell types. It has structural similarity to THYROXINE.Food Coloring Agents: Natural or synthetic dyes used as coloring agents in processed foods.Rose Bengal: A bright bluish pink compound that has been used as a dye, biological stain, and diagnostic aid.Tartrazine: An anionic, hydrophilic azo dye with an orange-yellow color used in fabrics, foods and cosmetics, and as a biological stain.Amaranth Dye: A sulfonic acid-based naphthylazo dye used as a coloring agent for foodstuffs and medicines and as a dye and chemical indicator. It was banned by the FDA in 1976 for use in foods, drugs, and cosmetics. (From Merck Index, 11th ed)Indigo Carmine: Indolesulfonic acid used as a dye in renal function testing for the detection of nitrates and chlorates, and in the testing of milk.DEAE-Dextran: Used as a support for ion-exchange chromatography.Ether: A mobile, very volatile, highly flammable liquid used as an inhalation anesthetic and as a solvent for waxes, fats, oils, perfumes, alkaloids, and gums. It is mildly irritating to skin and mucous membranes.Coloring Agents: Chemicals and substances that impart color including soluble dyes and insoluble pigments. They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS.Fluoresceins: A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.Azo CompoundsFluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.