Overview
Fluorescein 5(6) Isothiocyanate (FITC) is an amine-reactive dye used for covalent labeling of biomolecules such as proteins, peptides, and antibodies. It contains a reactive isothiocyanate group (-N=C=S) that forms a stable thiourea linkage with primary amines. This product is a mixture of the 5- and 6-isomers of FITC, a widely used standard formulation in fluorescence-based applications.

Applications of Fluorescein 5(6) Isothiocyanate (FITC)

• Antibody labeling for flow cytometry or fluorescence microscopy

• Peptide and protein labeling in biochemical and immunological assays

• Amine-functional biomolecule tagging for detection or purification workflows

Usage Considerations

Isothiocyanate labeling chemistry is preferred in applications where a stable thiourea linkage is desirable. Compared to NHS esters, FITC may offer longer shelf life in dry form and can be more suitable for extended labeling procedures due to its relatively slower reaction kinetics.