The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 30, 1998
Filed:
Dec. 12, 1996
Puthalath Koroth Sujeeth, Maryland Heights, MO (US);
Warner-Jenkinson Company, Inc., St. Louis, MO (US);
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.