e) In performing an immunological procedure, you add 2 mL of serum to 8 mL of saline. Two 1:2 serial dilutions are then made. What is the dilution of serum contained in the final tube?
you diluted it first by a facator of 5 (2ml to 10 ml).
then you diluted it by factors of 3.
dilution: 5*3*3=45 times
To find the dilution of serum contained in the final tube, we need to calculate the overall dilution factor.
In the given scenario, we start with 2 mL of serum and add 8 mL of saline, resulting in a total volume of 10 mL. This initial dilution factor can be calculated as follows:
Dilution factor = Volume of final solution / Volume of serum added
Dilution factor = 10 mL / 2 mL
Dilution factor = 5:1
Next, two 1:2 serial dilutions are made. A 1:2 dilution means that for every 1 part of serum, 2 parts of diluent (saline) are added. Since there are two serial dilutions, we multiply the dilution factors:
Overall dilution factor = Dilution factor of first dilution × Dilution factor of second dilution
Overall dilution factor = 5:1 × 1:2 × 1:2
To simplify, we can multiply the numerator (top) numbers together and the denominator (bottom) numbers together:
Overall dilution factor = (5 × 1) : (1 × 2 × 2)
Overall dilution factor = 5 : 4
Therefore, the dilution of serum contained in the final tube is 5:4.