Abstract: A process and apparatus for purifying water-insoluble particles is disclosed. The process comprises the steps of continuously recirculating a fluid aqueous suspension of the water-insoluble particles between a filtration system and a suspension reservoir; continuously conducting ultrafiltration of the recirculating suspension at the filtration system to separate an aqueous permeate containing the water-soluble impurities from the recirculating fluid aqueous suspension; continuously discharging the permeate generated by ultrafiltration; adding water to the recirculating fluid aqueous suspension undergoing ultrafiltration at approximately the same volumetric rate per hour as permeate is being discharged; monitoring the purity of the recirculating fluid aqueous suspension; and recovering the purified fluid aqueous suspension after the recirculating fluid aqueous suspension has reached a predetermined purity condition. An apparatus is also disclosed for carrying out the above process.

Abstract: An invention is disclosed which pertains to a method for purifying water soluble dyes, such as quinoline, fluoran, and xanthene dyes. The method comprises the steps of A) adding a metal salt to the water soluble dye to form a water insoluble dye salt of the metal; B) isolating the water insoluble dye salt of step A; C) converting the water insoluble dye salt of step B into a water soluble dye solution; and D) isolating the water soluble dye from the solution of step C. The present invention teaches a straight forward, economical, and environmentally sound method for purifying water soluble dyes of FDA certifiable purity and with an aesthetically improved shade.

Abstract: A process for the manufacture of fluorescein compounds suitable for conversion to FDA certified dyes is described. The fluorescein compounds, and in particular fluorescein (also known as Solvent Yellow 94 or D&C Yellow No.7) and 3,4,5,6-tetrachlorofluorescein, are made by a process involving the condensation of a phthalic anhydride with several molar excess of a resorcinol, the resorcinol being employed not only as a reactant, but also as a solvent for the reaction. This process also can employ the unreacted resorcinol and any intermediates or by-products from the condensation reaction as a reactant and as a solvent in subsequent condensation reactions.

Abstract: An improved dye composition for use in coating tablets and the like is constituted by a stable, aqueous suspension containing a water-soluble, nontoxic dye, an opacifying agent which may be titanium dioxide or iron oxide an immobilizing agent for immobilizing the dye and preventing it from migrating when applied to a tablet or the like, the immobilizing agent being constituted by a nontoxic metal salt present in an amount of from approximately 0.1 to 10 equivalents of metal per mole of dye, and water. The suspension may also contain a film-forming, water-soluble or water-dispersible edible polymer and a plasticizer. These compositions are used in lieu of lake compositions to produce tablets and the like with uniform, non-mottled coatings.

Abstract: An improved wet powder, edible, film-forming composition for use in coating tablets and capsules consists essentially of powdered pigment particles, a film-forming, water soluble or water-dispersible, edible polymer and up to approximately 30% by weight of water. Such compositions are formed by blending the pigment particles and the polymer and applying the water onto the pigment-polymer blend in atomized form. Similar wet powder, edible, clear, film-forming compositions for use in coating tablets and capsules with a clear coating consist essentially of a film-forming, water soluble or water-dispersible, clear, edible polymer and up to approximately 30% by weight of water and are formed by applying the water onto the polymer in atomized form. The application of water in this manner preconditions the polymer and permits the preparation of smooth stable coating suspensions upon dilution with additional water and without the formation of fish eyes.

Abstract: An improved wet powder, edible, film-forming composition for use in coating tablets and capsules consists essentially of powdered pigment particles, a film-forming, water soluble or water-dispersible, edible polymer and up to approximately 30% by weight of water. Such compositions are formed by blending the pigment particles and the polymer and applying the water onto the pigment-polymer blend in atomized form. Similar wet powder, edible, clear, film-forming compositions for use in coating tablets and capsules with a clear coating consist essentially of a film-forming, water soluble or water-dispersible, clear, edible polymer and up to approximately 30% by weight of water and are formed by applying the water onto the polymer in atomized form. The application of water in this manner preconditions the polymer and permits the preparation of smooth stable coating suspensions upon dilution with additional water and without the formation of fish eyes.

Abstract: An improved dye composition for use in coating tablets and the like is constituted by a stable, aqueous suspension containing a water-soluble, nontoxic dye, an opacifying agent which may be titanium dioxide or iron oxide an immobilizing agent for immobilizing the dye and preventing it from migrating when applied to a tablet or the like, the immobilizing agent being constituted by a nontoxic metal salt present in an amount of from approximately 0.1 to 10 equivalents of metal per mole of dye, and water. The suspension may also contain a film-forming, water-soluble or water-dispersible edible polymer and a plasticizer. These compositions are used in lieu of lake compositions to produce tablets and the like with uniform, non-mottled coatings.

Abstract: Improved stable, fluid, aqueous dispersion compositions comprise a pigment, an alkali metal, alkaline earth metal or ammonium salt of a linear aliphatic substituted glycine such as a salt of ethylene diamine tetraacetic acid or nitrilo triacetic acid as a stabilizing agent, and water. The dispersion composition may additionally contain a lower alkanol such as methanol and/or a water soluble plasticizer such as propylene glycol. Coating compositions for use as a film coating for tablets and the like contain the above-described stable, fluid, aqueous dispersion composition, a water soluble plasticizer, a film coating resin, and water. The described fluid, aqueous dispersion compositions have been found to remain stable for extended periods exceeding six months.