FITC

FITC is fluorescein isothiocyanate, a reactive derivative of fluorescein used to attach a fluorescent label to suitable targets. Its reactive group couples to accessible amino groups, so labeling a protein can make that protein observable by fluorescence microscopy or flow cytometry.

The label's presence is distinct from the specificity of the experiment. Unbound dye must be separated from the intended conjugate, and an unlabeled control estimates autofluorescence. Labeling can alter the target's behavior, while bleaching and environment-dependent emission affect measured intensity. ^[ref]