This document discusses methods for determining the biomass, protein, carbohydrate, and lipid content of microalgal cultures. It involves measuring absorbance of cultures using a spectrophotometer to estimate dry biomass based on a regression equation. Culture samples are filtered and dried to directly measure dry biomass. Protein content is measured through a Bradford assay, while carbohydrates and lipids are measured through spectrophotometric assays after extraction from dried biomass. The methods allow optimization of medium composition and culture conditions for microalgal growth experiments using a Plackett-Burman design.