Microalgae Compositional Analysis Laboratory Procedures
NREL develops laboratory analytical procedures (LAPs) for microalgae. These procedures help scientists and analysts understand more about the chemical composition of algae as a feedstock to convert to biofuels.
NREL's Algal Biofuels Research team can work with you to analyze the chemical composition of algae as a biomass feedstock.
NREL wrote these analytical procedures to help the research community analyze algae.
Summative Mass Analysis of Algal Biomass — Integration of Analytical Procedures
This procedure guides the integration of LAPs to measure algal biomass constituents in an unambiguous manner and ultimately achieve mass balance closure for algal biomass samples. Many of these methods build on years of research in algal biomass analysis.
By combining the appropriate LAPs, the goal is to break the biomass sample into constituents that sum to as close to 100% by weight as possible. Some of these constituents are individual components, such as carbohydrates and lipids as total fatty acids, and some can be groups of compounds, such as extractable lipids.
Determination of Total Carbohydrates in Algal Biomass
This procedure uses two-step sulfuric acid hydrolysis to hydrolyze the polymeric forms of carbohydrates in algal biomass into monomeric subunits. The monomers are then quantified by either high-performance liquid chromatography (HPLC) or a suitable spectrophotometric method.
An optimized hydrolysis procedure is expected to yield complete hydrolysis of all polymeric structural and storage carbohydrates into monomeric sugars. A range of sequential and optimized inorganic acid hydrolysis conditions with respective hydrolysis liquor collection and analysis should be carried out for algal biomass.
Determination of Total Lipids as Fatty Acid Methyl Esters
This procedure is based on a whole biomass transesterification of lipids to fatty acid methyl esters (FAME) to represent an accurate reflection of the potential of microalgal biofuels. Lipids are present in many forms and play various roles within an algal cell, from cell membrane phospholipids to energy stored as triacylglycerols. The ability to identify and accurately quantify the fatty acid content of these lipids, as well as free fatty acids, is essential to evaluating fuel potential and establishing a comprehensive compositional analysis of algae.
Determination of Total Solids and Ash in Algal Biomass
This procedure describes the methods used to determine the amount of moisture or total solids present in a freeze-dried algal biomass sample, as well as the ash content. A traditional convection oven drying procedure is covered for total solids content, and a dry oxidation method at 575°C is covered for ash content.
Algal biomass samples may contain a high and varying percentage of moisture, which can change rapidly when exposed to ambient humidity levels. These samples also may contain varying percentages of ash depending on species and the presence of growth media.