Question

You have the following buffer recipe and decide to make up some concentrated solutions first so that you won't have to weigh out dry ingredients, wait for them to dissolve, and correct the pH every time you make it. How much dry ingredients do you use for each of the following 4 stock solutions? Show you work and include units in your calculations.

The Buffer Recipe is:

150 mM NaCl (formula weight 58.44 g)

10 mM Tris pH 8.0 (formula weight 121 g)

2 mM EDTA (formula weight 292 g)

0.2% bovine serum albumin

-Stock 1 of 4: 3 M NaCl, 100 mL ________ ?

-Stock 2 of 4: 1 M Tris, pH 8.0, 100 ml ________ ?

-Stock 3 of 4: 0.5 M EDTA, 500 mL ________ ?

-Stock 4 of 4: 10% bovine serum albumin, 10 mL ________ ?

Answer 1

1. NaCl- formula weight is 58.44 gm

           thus to make 1M , 1000 ml we need 58.44 gm NaCl

                   for 1M, 100 ml 58.44 X 100 / 1000 = 5.844gm

             then for 3M we require- 5.844 X 3= 17.532gm

2. formula weight for Tris is 121 gm

thus for 1M, 1000ml Tris solution 121 gm of salt is required.

            for 1M, 100 ml we require 121 X 100 / 1000= 12.1 gm of tris

3. EDTA formula weight is 292gm

for 1M, 1000ml soluiton, 292 gm of EDTA is required

   for 1M, 500ml solution 292 X 500/ 1000= 146gm of EDTA is required.

now, for 0.5M , 500ml solution 146 X 0.5/ 1= 73 gm of EDTA is rquired.

4. for the preparation of 10% bovine serum albumin,

10gm of BSA to be dissolved in 100ml of water

so , 100ml will require 10gm

thus 10ml will require 10 X 10 / 100= 1 gm

therefore 1gm of BSA is required to dissolve in 10ml of solution / water.