Fluorescein dicaprylate WS1 is a non-fluorescent water-soluble fluorescein derivative.  Esterases hydrolyze the dicaprylate group producing the highly fluorescent product fluorescein. This water-soluble luorescein dicaprylate may stain Samonella in green fluorescence. It is a fluorogenic substrate for C8 esterase that generates green fluorescence upon esterase cleavage. Compared to the fluorescein dicaprylate esterase substrate, this fluorescein dicaprylate WS1 is much more water-soluble while fluorescein dicaprylate precipitates in aqueous solutions, making it hard to be used in continuous assays.