Comparison of fatty acid analysis methods for assessing biorefinery applicability of wastewater cultivated microalgae

In this study, we compared the performances of four different gas chromatography (GC) based microalgal fatty acid analysis methods that are typically applied to biorefinery research using wastewater-adapted microalgae. Compared with the HP-5-type non-polar column, WAX-type polar columns exhibited excellent abilities to quantitatively separate C(16)-C(18) polyunsaturated fatty acids (PUFAs) from selected wastewater-adapted microalgae (Chlorella vulgaris, Ankistrodesmus gracilis and Scenedesmus quadricauda) isolates. GC-mass spectroscopy (MS) using the WAX-type polar column provided the strongest detection sensitivity among the tested methods by lowest detection limit, and GC-flame ionized detector (FID) with the same polar column exhibited nearly consistent results to GC-MS analysis. Our statistical comparison of microalgal fatty acid composition profiles generated using various GC methods, microalgal resources and culture media (wastewater, BG11 and nitrogen limitation) suggested that an appropriate GC method and algal resource choice are more important than the optimization of culture conditions to evaluate the applicability of microalgal biorefinery using wastewater resources.