| 1. Label four sterile 0.2 mL PCR tubes as 1, 2, 3 and 4. | |
| 2. Add 100 µL of sterile water (in the tube labeled H2O) to each tube. | |
| 3. Add 100 µL of the original sample (in the tube labeled S) into the tube 1 and mix well by pipetting. | |
| 4. Transfer 100 µL from the tube 1 into the tube 2, mix well by pipetting. | |
| 5. Transfer 100 µL from the tube 2 into the tube 3, mix well by pipetting. | |
| 6. Transfer 100 µL from the tube 3 into the tube 4, mix well by pipetting. | |