EVALUATION OF THE PIGMENT COMPOSITION OF MICROALGAE PORPHYRIDIUM PURPUREUM ACCORDING TO THE TRUE ABSORPTION SPECTRUM OF THE CULTURE USING A SPREADSHEET PROCESSOR
The paper describes a method for mathematical separation of the absorption spectrum of the culture of the red seaweed Porphyridium purpureum using a spreadsheet processor - the Microsoft Excel program. This method represents the analysis and separation of overlapping pigment bands in the native absorption spectrum of a culture. The culture spectra were recorded on a spectrophotometer near and at a distance from the entrance window of the integrating sphere. The true absorption spectrum is calculated, compensated for scattering in the region from 400 to 750 nm. The true absorption spectrum of the culture was approximated by a mathematical model in which the unknown parameters are the concentrations of chlorophyll a, B-phycoerythrin, R-phycocyanin, allophycocyanin, and total carotenoids. Pigment models are represented by the sum of normal distribution curves. The implementation of calculations that perform the selection of pigment concentrations by minimizing the sum of squared deviations between the true absorption spectrum and its mathematical model was performed using a spreadsheet using the "Search for a solution" tool. The proposed method of mathematical processing of the spectrum can be used as an express method for determining the concentration of pigments in culture, without isolating pure pigments. The application of this method makes it possible to evaluate the contribution of pigments to the total absorption spectrum of the culture.