An amplitude modulation fluorometric method for phytoplankton classified measure

We describe a fluorometric method for phytoplankton classified measure. The sinusoidal-amplitude-modulation (SAM) technique is used in this method. The fluorescence of samples is excited in blue, green and amber excitation channels and demodulated simultaneously. We demonstrate experimentally that the system offers a detection limit of chlorophyll a down to 0.005 μg/L and a detection time of 1 s. Compared with the existing pulse-amplitude-modulation (PAM) fluorometers, this method has advantages of better detection limit and shorter detection time, which can facilitate the phytoplankton classified measure.