In a series of serial dilutions, if 10 µL of serum is added to the first tube containing 0.79 mL of diluent, what is the serum dilution of tube 7?

To determine the serum dilution in tube 7 after a series of serial dilutions, it’s crucial to understand how serial dilutions work. In this case, 10 µL of serum is added to the first tube with 0.79 mL of diluent. The total volume in tube 1 will then be:

• Volume of serum: 10 µL
• Volume of diluent: 0.79 mL (or 790 µL)

The total volume becomes 10 µL + 790 µL = 800 µL. Consequently, the dilution factor for tube 1 is calculated as follows:

[ \text{Dilution Factor for Tube 1} = \frac{\text{Total Volume}}{\text{Volume of Serum}} = \frac{800 , \mu L}{10 , \mu L} = 80 ]

This means the first tube has a dilution of 1:80.

For each subsequent tube, if the same volume of diluent (which must be consistent) is added, this process is repeated. Assuming that standard practice continues, each of the next tubes would receive a dilution that follows the same pattern, typically halving or following another consistent ratio