Question

homework"""""""

A patient serum is serially diluted five. Tube one contains 100 ul of serum and 200 ul of saline. Tubes two through five also contains 200uL of saline. 100 ul of tube 1 dilution is added to tube #2, mixed and then 100uL of tube #2 dilution is added to tube #3 and the serial dilution is completed in this manner. What is the original concentration of EBV antibodies if the final concentration if the final concentration is 21?

Answer 1

Answer- The original concentration of EBV antibodies in patients serum sample is 5103.

Explanation-

1. A patient serum is seriallly diluted five in 1:3 dilution by adding 100ul serum in first tube containing 200ul saline. Then 100ul diluted serum from first tube is added in second tube containing 200ul saline and this is also 1:3 dilution. Dilution is continued till fifth tube and in each tube serum is diluted three times.

2. To calculate concentration of EBV antibody in patient serum simply concentration in final tube is multiplied with 3 and this calculation done upto tube 1.

Given is final concentration of EBV antibodies is 21.

Concentration of antibody in 5th tube = 21

Concentration of antibody in 4th tube = 21×3= 63

Concentration of antibody in 3rd tube = 63×3= 189

Concentration of antibody in 2nd tube = 189×3= 567

Concentration of antibody in 1st tube = 567×3= 1701

The concentration of antibody in first tube is 1701 which is 1:3 diluted. So that concentration of antibody in 100ul serum sample is- 1701×3= 5103.

So that the concentration of EBV antibodies in patient serum sample which is added in the amount of 100ul is 5103.