Measurement and feature analysis of absorption spectra of four algal species

Two methods for particulate pigments （i.e., quantitative filter technique, QFT, and in vivo measurement, InVivo, respectively） and two methods for dissolved pigments （i.e., Acetone Extracts, AceEx, and high-performance liquid chromatography, HPLC, respectively） were used to obtain the optical absorption coefficient spectra for cultures of four typical algal species. Through normalization and analysis of the spectra, it is shown that （1） the four methods are able to measure optical absorption spectra of particulate and/or dissolved pigments; （2） that the optical absorption spectra of particulate and dissolved pigments were consistent in terms of the peak position in the blue wavelength, and the difference of the peak position in the near infrared wavelength was -10 nm between each other; and （3） that the leveling effect of the absorption spectra of particulate pigments was significant. These four methods can all effectively measure the absorption coefficients of phytoplankton pigments, while each one has its unique advantages in different applications. Therefore, appropriate method should be carefully selected for various application due to their intrinsic difference.