Question

4. You need 3.2 x 10 cells in a total volume of 800 ul. What volume from my tube of cells which are at 8.1 x 10' cells/ml do I need and how much media needs to be added. (4 pts)

Answer 1

Original cell concentration = 8.1 x 107 cells/ml

Required cell concentration = 3.2 x 105 cells/ml

Required volume = 800 µl

Volume added to original cell concentration to make new cell concentration 3.2 x 105 cells/ml in 800 µl=?

Here, we can apply following formula

S1V1 = S2V2

S1 = 8.1 x 107 cells/ml

S2 = 3.2 x 105 cells/ml

V1 = ?

V2 = 800 µl = 0.8ml

We apply givenn information in question and calculate

8.1 x 107 x V1 = 3.2 x 105 x 0.8

V1 = (3.2 x 105 x 0.8)/ 8.1 x 107

V1 = 0.306 x 10-2 ml = 3.06 x 10-3 ml = 3.06 µl (round off value 3)

Volume of media needed = V2 - V1

= 800 - 3 = 797 µl

Hence, you have to draw  3 µl of cells from original tube and add 797 µl media to make 3.2 x 105 cells in  800  µl .