Many natural and synthetic molecules contain aldehyde or ketone carbonyl groups. These carbonyls react with hydrazides with the formation of hydrazones. The reaction is spontaneous at pH values around neutral, and the resulting hydrazones are very stable. Compounds containing 1,2-diol function, like sugars, can be oxidized with sodium periodate with the formation of carbonyl compounds for the subsequent modification with hydrazides. This is an efficient method for the labeling of glycoproteins (like antibodies), and polysaccharides. FAM hydrazide is a hydrazide label for the attachment of fluorescein, a bright dye for 488 nm channel, to carbonyl compounds

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.