Fluorescein (FAM) is a popular fluorophore that has bright emission in the green area of visible spectrum. This derivative of fluorescein contains tetrazine moiety. Tetrazines react with trans-cycloalkenes and other strained olefins in a reaction called inverse electron demand Diels-Alder reaction (ied-DA). The reaction is very quick and specific. The reagent contains pure 6-isomer of FAM.

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.