(602as) Rapid Lipid Quantification of Algal Biomass Using Thermo-Gravimetric Analysis

Algae, especially green algae and diatoms, have the potential to accumulate high amounts of lipid (upto 50 wt% of dry weight) through chemical and physical stimuli, when grown in laboratory conditions.  However, most of these algae cannot withstand the harsh and non-sterile environmental conditions encountered in actual production systems.  At present, intense research efforts are devoted to screening for algal species that can survive and accumulate lipids in the open-pond non-sterile production environments. Simple, rapid and accurate lipid quantification techniques are of great value for rapidly screening a large variety of strains. In this regard, traditional laboratory techniques for lipid quantification, such as Bligh and Dyer, Folch, acid/base catalyzed trans-esterification methods are not convenient. They are time-consuming, require volatile chemicals and expensive analytical facilities, and involve several process-steps. In this paper, we will introduce a simple, rapid and accurate lipid quantification technique based on thermo-gravimetric analysis (TGA).

The main components of oleaginous algae are protein, starch and lipids. Our technique is based on the observation that the protein, starch and lipid portions undergo thermal degradation over distinct non-overlapping temperature intervals. Proteins are most thermally labile followed by starch and lipids.  Lipids undergo complete volatilization over a narrow temperature interval of 370-450 °C, without leaving behind any biochar. Therefore, lipid content in the algal sample can easily be correlated to the weight loss of the sample during TGA over this narrow temperature range.  Lipid content estimates, for several oleaginous algae and oil seeds, from this approach will be reviewed relative to the results from traditional lipids quantification techniques.