Dataset on the absorption characteristics of extracted phytoplankton pigments

This article presents the raw and analysed data on the absorption features of 30 pigments commonly occurring in phytoplankton. All unprocessed absorption spectra are given between 350 and 800 nm. The presented data also gives information on the wavelength of the main absorption peaks together with associated magnitudes of the concentration-specific absorption coefficient.


Experimental design, materials, and methods
Pigment standards for chlorophyll-a and chlorophyll-b were prepared from extracts purchased from Sigma-Aldrich (www.sigmaaldrich.com), while other pigment standards were obtained from DHI (www.dhigroup.com). The source and the batch/lot number of each pigment are given in Tables 1  and 2. The standards were in either 90% acetone, 100% acetone or 100% ethanol ( Table 1, Table 2). The final concentrations of the standards were measured by HPLC (High Performance Liquid Chromatography) with the CSIRO method [2], which is a modified version of the [3] technique, using C 8 column and binary gradient system with an elevated column temperature. Pigments were identified by their retention time and their absorption spectra from the photo-diode array detector. Next, the pigment concentrations were determined through peak integration performed in Empower © software.
The absorption spectra of the pigment standards were measured in a 1-cm quartz-glass cuvette using a Cintra 404 (GBC Scientific Equipment Ltd.) UV-VIS dual-beam spectrophotometer against the pure solvent as a blank. The spectra were measured over the 350e800 nm spectral range in 1.3 nm increments. The absorbance (OD) obtained from the measurements was converted to an absorption coefficient (a(l), m À1 ) by multiplying the appropriate baseline-corrected optical density values of each standard by 2.3 and dividing by the optical path length/cuvette thickness (0.01 m): Finally, the concentration specific absorption coefficients (a * (l), m 2 g À1 ) were calculated by dividing each absorption coefficient by the respective pigment concentration.
Data presented in Figs. 1 and 2 and in Tables 1 and 2 were null-point corrected by subtracting the absorption coefficient value at 750 nm assuming no absorption of pigments in the NIR region of the The absorption spectra were measured in a 1-cm quartz-glass cuvette using a dual-beam spectrophotometer against the pure solvent as a blank. The spectra were measured over the 350e800 nm spectral range in 1.

Value of the data
This dataset is unique in that it provides the absorption characteristics together with a pigment concentration for 30 different pigments. From this, concentration-specific absorption coefficients are obtained which can be used for both phytoplankton and bio-optical studies.
The dataset can be used in models pertaining to phytoplankton behavior or for theoretical experiments. The dataset can be used to both compare to in situ experimental results or to help explain experimental results. The dataset can be base for theoretical experiments in phytoplankton physiology or ecology and marine bio-optics.    Table 1 Location of the main absorption peaks and the associated magnitude of the concentration specific absorption coefficient for chlorophyll-a, chlorophyll-b, DV chlorophyll-a, chlorophyllide-a, phaeophorbide-a, phaeophytin-a, chlorophyll-c3, and chlorophyll-c2. spectrum [4]. The spectra were also interpolated to yield absorption coefficients between 350 and 750 nm with the resolution of 1 nm using linear interpolation method (MATLAB, interp1.m). Due to differences in the organic solvent and water refractive index (i.e. 1.352 for acetone, 1.361 for ethanol and 1.330 for water), the spectra may be wavelength-adjusted by using the ratio between the refractive index of the solvent and the water as done by [1].