The US Patent and Trademark Office has awarded US Patent No. 6,426,190 to Carnegie Mellon University for a method of detecting differences between two or more protein samples, including post-translationally modified proteins. The patent, entitled “Difference detection methods using matched multiple dyes,“ specifically describes a technique for mixing two protein samples, each labeled with a distinct luminescent dye, and then separating the proteins using electrophoresis or chromatography.