The recovered oil was then converted to the corresponding fatty acid methyl esters via transesterification for subsequent GC analysis. The results (Figure ) indicated that no polyunsaturated fatty acids remained in this mixture. This implies that sulfur reacted with the PUFAs and converted them into the insoluble polymer material. Furthermore, the saturated fatty acids were more effectively enriched than the benchmark hydrogenation method: 90% of this mixture was derived from saturated fatty acids and <10% was derived from monounsaturated fatty acids (Figure and Figures ). These results were corroborated by 1 H NMR analysis of the recovered algae oil (Figure ). This means that the polyunsaturated triglycerides in the algae oil could be quantitatively converted into a copolymer through reaction with sulfur. The unreacted oil is comprised solely of saturated and monounsaturated species, both of which are suitable as biodiesel precursors. In this way, a single reaction of the crude algae oil with sulfur provides a novel polymer that is easily separable from a biodiesel precursor.