– Europium W1024 isothiocyanate (ITC) is a lanthanide-based fluorophore characterized by its long emission lifetime and significant Stokes shift, featuring excitation and emission maxima at 340 and 613 nm, respectively. This compound includes a reactive isothiocyanate handle that engages with primary amino groups in alkaline conditions. It maintains stability under high temperatures, in the face of elevated EDTA concentrations, or at low pH levels, though it falters when exposed to manganese. Commonly, Europium W1024 ITC serves as a donor fluorophore in time-resolved fluorescence resonance energy transfer (TR-FRET) applications, offering the advantage of a prolonged measurement window for observing acceptor fluorescence and minimizing autofluorescence interference through its extended emission lifetime.