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.

Lysosome Labeling Protocol[3]
Step 1: Dye Uptake
Seed Thio-macrophages or J774.2 cells onto coverslips.
Incubate cells in medium containing Lucifer Yellow CH (1 mg/ml) for 1-2 hours.

Step 2: Washing
Wash the cells with ice-cold PD buffer (137 mM NaCl/3 mM KCl/7 mM phosphate, pH 7.4).

Step 3: Dye Efflux
Transfer the cells to M1OF medium without Lucifer Yellow CH and continue incubation for 20-30 minutes at 37°C to allow dye efflux from the pinosomal/endosomal compartment.

Step 4: Microscopic Observation
Invert the coverslip onto a microscope slide with M1OF (37°C) as the cell medium.
Observe live cells using a Zeiss light microscope equipped with a 63x oil immersion lens (n.a. 1.4), and capture images with Kodak Tri-X film (ASA 400).

Notes:
This protocol is based on the reference literature. According to other sources and depending on the experimental goals, the working concentration of Lucifer Yellow CH may range from 0.05 to 1 mg/mL. Please adjust the concentration based on the specific requirements of your experiment.