Question

How do I do the dilution calculations for this question?

You will be given stock concentrations of both BSA and GAPDH at 4 mg/ml. Dilute the BSA and GAPDH to be used for the plate coat to a final concentration of 10 μg/ml in freshly prepared phosphate buffered saline (1 x PBS, 0.01M phosphate, 0.15M NaCl, pH 7.4).

Answer 1

Ans. Given, stock concentration [BSA] = [GAPDH] = 4 mg mL^-1 = 4000 ug mL^-1

            Final concentration [BSA] = [GAPDH] = 10 ug mL^-1

Note that the required volume of the final diluted solution has not been mentioned in the question. So, the dilution pattern would differ depending on the required volume of the diluted solution.

Also, to be economic, it’d be desirable to prepare small volume of the solution

# Let the required volume be 4.0 mL

Using C1V1 (stock solution) = C2V2 (final solution)

            4000 ug mL^-1 x V1 = 10 ug mL^-1 x 4.0 mL

            Or, V1 = (10 ug mL^-1 x 4.0 mL) / 4000 ug mL^-1 = 0.01 mL = 10.0 uL

# Preparation: To a 3990 uL of buffered saline taken in a clean and sterile 5-mL tube, add 10.0 uL of the stock solution. Mix well by reverse pipetting. The resultant solution is 10 ug/mL in both [BSA] and [GAPDH].