Molina Grima et al. [24] have shown that lipid extraction from P tricornutum can be achieved on wet biomass. The study achieved 90% fatty acid yield on wet bio­mass in comparison to a 96% fatty acid yield from lyophilised biomass. The wet biomass was extracted at approximately 20% (w/v). The wet biomass leaving the dewatering stage from this study is at 50% (w/v). Therefore, the extraction method described by Molina Grima et al. [24] should provide enhanced interaction between the solvent and the cells. However, this extraction method involved three steps: (1) direct saponification of biomass oil, (2) extraction of unsaponifiable lipids and (3) extraction of purified free fatty acids (FFA) [24]; hence, it was compared to a simi­lar method conducted by Ramirez Fajardo et al. [27], which was a two-step solvent extraction process. The two-step method involved lipid extraction using ethanol and lipid purification using a two-phase system of hexane and water. The crude lipid extraction involved a reaction between ethanol (96% v/v) and the biomass in an agitated tank for ~20 h. The crude lipid contains both saponifiable and unsaponifiable lipids. The saponifiable lipids include glycolipids and acylglycerols which are use­ful for biodiesel, whereas unsaponifiable lipids contain components such as amino acids and chlorophyll pigments which must be removed from the extract [27]. Water is added to the ethanol/crude-extract mixture to create a hydroalcoholic solution, and hexane is added to create a biphasic extraction system that separates the exploit­able and unusable lipids thus purifying the extract. The majority of the saponifiable lipid will be found in the hexane phase, whereas the more polar components will remain in the hydroalcoholic phase [ 24] . It is assumed that hexane purification reaches 80% recovery after four continuous extractions.