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# Calculation: Preparing a Solution of BSA

BIOCHM-4@IJKX

You need to make up exactly 5.0 mL of a 2.5 mg/mL BSA (bovine serum albumin) solution in 0.05M NaCl to use as your standard protein solution. You have already carefully prepared stock 1 M NaCl.

Which of the following statements describes the BEST approach to preparing this solution?

A

Weigh out 2.5 mg BSA and slowly add this to 5 mL of 1 M NaCl. After the BSA is fully dissolved, dilute the final solution 20-fold with water yielding 0.05M NaCl.

B

Prepare 5 mL of 0.05M NaCl by diluting 0.25 mL of the 1M NaCl stock with 4.75 mL water. Add 2.5 mg BSA directly to this 5.0 mL. Allow it to dissolve slowly.

C

Prepare 5 mL of 0.05M NaCl by diluting 0.25 mL of the 1M NaCl stock with 4.75 mL water. Add 2.5 mg BSA to about 4.5 mL of the 0.05M NaCl solution and allow it to dissolve slowly. After it is fully dissolved, bring the final volume of the solution to 5.0 mL with 1M NaCl.

D

Prepare 5 mL of 0.05M NaCl by diluting 0.25 mL of the 1M NaCl stock with 4.75 mL water. Add 2.5 mg BSA to about 4.5 mL of the 0.05M NaCl solution and allow it to dissolve slowly. After it is fully dissolved, bring the final volume of the solution to 5.0 mL using any remaining 0.05M NaCl solution.

E

Prepare 5 mL of 0.05M NaCl by diluting 0.25 mL of the 1M NaCl stock with 4.75 mL water. Add 2.5 mg BSA to about 4.5 mL of the 0.05M NaCl solution and allow it to dissolve slowly. After it is fully dissolved, bring the final volume of the solution to 5.0 mL with water.

F

Prepare 5 mL of 0.05M NaCl by diluting 0.25 mL of the 1M NaCl stock with 4.75 mL water. Add 2.5 mg BSA to about 4.5 mL of the 0.05M NaCl solution and allow it to dissolve slowly. After it is fully dissolved, bring the final volume of the solution to 5.0 mL with water and allow the solution to shake vigorously overnight at 4${ ℃ }$.