TAMRA (aka TMR or tetramethylrhodamine) is a xanthene dye that has been used as a fluorescent label for decades. Xanthene dyes are available as two isomers (called 5- and 6-isomers) that have almost identical fluorescent properties, but need to be separated to avoid doubling and smearing of labeled product peaks or bands during chromatography or electrophoresis. This is a pure 6-isomer of TAMRA maleimide, used for the labeling of proteins and peptides via thiol (SH) groups

Providing storage is as stated on the product vial and the vial is kept tightly sealed, the product can be stored for up to 24 months.
Wherever possible, you should prepare and use solutions on the same day. However, if you need to make up stock solutions in advance, we recommend that you store the solution as aliquots in tightly sealed vials at -20°C. Generally, these will be useable for up to one month. Before use, and prior to opening the vial we recommend that you allow your product to equilibrate to room temperature for at least 1 hour.