Figure 3.

Purification of the pheromone by reversed-phase HPLC. A total of 220 ml of dilute pheromone solution obtained by steam distillation (derived from ca. 2.5 × 10¹³ cells) was loaded in successive 5-ml portions onto a C18 column (250 × 4.6 mm, 5 μm) at 1 ml/min. Pheromone was eluted at 1 ml/min with a gradient (dashed line) of CH₃CN in acetate buffer. Fractions were collected, and aliquots were assayed for pheromone activity. The biologically active fractions at a retention time of ca. 28 min are indicated by a bar.