Also available in 1 mL, 1 mg, 5 mg, 25 mg, 50 mg and bulk. Please contact Fisher for quotes. Lucifer Yellow CH dipotassium is a water-soluble fluorescent tracer that labels endocytosis vesicles in cells.Lucifer Yellow CH dipotassium excites and emits at a maximum wavelength of 430 nm and 540 nm, respectively. Purity 99.71%