Digital Photo Fluorometer Model 681 is designed for precise analysis of fluorophors such as vitamins, quinine, steroids, fluorescein, metal complexes, etc. The Fluorescence is caused by the absorption of radiant energy and the re-emission of some of its energy in the form of light. In fluorescence, the excited molecule returns to the ground state immediately after excitation, when the fluorescent molecule is excited at the fixed wavelength (primary filter). The amount of light emitted is measured at the particular wavelength (secondary filter). Fluorometer method for the determination of fluorophors is more sensitive than the Colorimetric method.

The Primary Filters – Corning 5840 & Corning 5113 and secondary filters – Corning 4308, Corning 3486 and Corning 3385 mounted on holders are supplied with the instrument The fluorescence is collected at 90-degree angle to minimize the interference of excitation source to fall on the sample solution only during a measurement.