Patent ID: 8257975

Claim:
A method to determine the identity of a functional fluid comprising: (1) adding a marker component to a functional fluid; (2) using the marked functional fluid in an application, where the application has a set of service conditions, and where the fluid used in the application is exposed to the service conditions, and wherein the marker component survives the service conditions of the application; (3) obtaining a sample of the marked functional fluid before, during or after the fluid's use in the application; (4) placing the sample of functional fluid and a reagent solution on a test medium such that they are in contact with each other; (5) reacting the marker in the functional fluid sample on the test medium with the reagent solution to produce a visible change; (6) analyzing the results of the reaction by determining the resultant visible change; and (7) determining the identity of the functional fluid based upon analysis of the results; wherein the sample of the marked functional fluid and the reagent solution are placed on the test medium in any order; wherein the reagent solution comprises a mineral acid, an organic acid, an organic base, a mineral base, an oxidizing agent, a reducing agent, a chelating agent, a metal salt, or combinations thereof; wherein the reagent solution and sample of functional fluid are placed onto the test medium using a dropper, pipette, squeeze container, pour container, pump without propellant, spray, roller, brushes, dipping container or mixtures thereof; wherein the marker component comprises a marker compound represented by the following formula: wherein each R 1 is independently hydrogen, or a —COOH group; and wherein each R 2 is independently hydrogen, or an alkyl group wherein any alkyl groups present independently contain from 1 to 5 carbon atoms.