Representative HPLC chromatograms acquired based on absorbance at 650 nm for: (A) D-Cy5 conjugate, (B) kidney extract, and (C) urine obtained from rabbit 24 h post injection of D-Cy5, (D) Cy5, (E) kidney extract, and (F) urine acquired from rabbit 24 h post injection of the dye. Insets, UV–vis spectra recoded under peaks related to D-Cy5 and Cy5 in samples used as standards, kidney extracts, and urine. Results indicated the presence of D-Cy5, and relatively low levels of free, released dye, in specimens collected from rabbit treated with the conjugate. Relatively low Cy5 levels were detected in animals injected with free Cy5.