||A high performance in situ fluorometer which can be configured and factory scaled for various fluorometric analyses. These include detection of blue-green algae (phycocyanin, phycoerythrin), CDOM/FDOM, fluroescent dye tracing (fluorescein, rhodamine, PTSA), hydrocarbons (crude oil, refined fuels), wastewater monitoring (optical brighteners, tryptophan), turbidity, and chlorophyll in vivo (blue excitation, red excitation). Custom optics are available between 260-900 nm. Depending on the configuration, the instrument has a minimum detection limit ranging from 0.01-10 ppb, 10 ppm, 0.03-0.3 ug/L and 0.05 NTU. The instrument can be used in depths up to 600 m and in water temperatures of -2 to 50 degC.