I am working with Fluorescence spectrophotometer (Model:F-2700 FL) to determine concentration of chlorophyll a and carotenoids in cyanobacteria. I set up the excitation and emission wavelength of beta carotene as 425 nm and 520 nm respectively. While chorophyll a excitation and emission wavelength were set to 430 nm and 680 nm respectively. By running the analysis, a longer and a shorter peaks appeared as could be seen in the picture. Each time i change the excitation and emission wavelength in order to determine other pigments such as chlorophyll a, lutein, astaxanthin e.t.c i got similar peaks. Please how can i identify a particular pigment and its concentration from the spectral peaks? why the peaks remain same each time i run the test despite variation in the wavelength? Beside HPLC, can i use the fluorescence machine to characterize carotenoids composition? I need guidance Please.