This protocol was adapted for chiral analysis of citral and geranial reduction. Reactions were run for 180 min at 30 °C and contained 0.5 μm enzyme, 1 mm citral (Sigma-Aldrich, C83007) or geranial, 2% tetrahydrofuran as a co-solvent, 1 mm NADPH, and buffer C up to a volume of 300 μl. Commercial rac-citronellal (Sigma-Aldrich, 27470) and S-citronellal (TCI, C1454) were used as standards. From 100 μl of ethyl acetate extract, 1 μl was injected at a 10-fold split ratio into a Restek SKY Liner with wool for split injection. The chiral separation was performed on a Supelco β-DEX225 column (30 m × 250 μm, 0.25-μm film thickness) with an isothermal gradient at 93 °C for 33 min at an average velocity of 26 cm/s. Runs were concluded with a temperature gradient up to 220 °C at a rate of 40 K/min and a final hold time of 4 min.