Principle Because different pigments are specific for individual phytoplankton taxa, the study of plant pigment diversity, concentration and distribution in the water column has become a useful tool when trying to describe the phytoplankton community. The difference in polarity and molecular size between photosynthetic pigments is used to separate these molecules by high-performance liquid chromatography. The integration of the area under a particular peak in absorbance or fluorescence at 436 nm or 640 respectivelly is a measure of the amount of pigment injected in the column. Precautions Light causes deterioration in pigments. Therefore, the samples should always be protected from exposure to light.
Pigments can also decompose spontaneously, particularly when concentrated onto filters.
Therefore, filters are stored in liquid nitrogen to minimize pigment degradation. Sampling, Filtration, Extraction and Storage 3.1. The filtration bottles and caps are rinsed three times with the sample before filling. Sampling depths correspond to those used for primary productivity. All filtration procedures are done under subdued light conditions.