1. Serial Dilution 1 mL stock solution & 9 ml saline 9 mL stock solution 9 mL saline solution 9 mL saline solution 9 mL saline solution 9 mL saline solution 1 mL D2 solution to D3 1 mL D3 solution to D4 1 mL D4 solution to D5 1 mL D5 solution to waste D1 D2 D3 D4 D5 D6