# Cell count - Please help - (Apr/13/2010 )

The easiest thing to do is to go back to the equations -

For dilutions use Vi*Ci = Vf*Cf where V=volume, C=concentration, i= initial and f=final.

from your post above you have a cell suspension at 1.77*10^{6} cells/ml (Ci)

and you want 0.5*10^{6} cells/ml (Cf) in a volume of 17.7 ml (Vf)

`so Vi * 1.77*10^6 cells/ml = 17.7 ml * 0.5*10^6 cells/ml`

Vi * 1.77*10^6 cells/ml = 8.85*10^6 cells

Vi = 8.85*10^6 cells

-----------------

1.77*10^6 cells/ml

Vi= 5 ml

So you take 5 ml of your cell suspension and add it to 12.7 ml (17.7ml - 5ml = 12.7ml) of medium.

If you always go back and state the variables you have and what you are looking for and the equation you are going to use to solve the problem, you shouldn't have difficulties! Also remember to keep your units the same always (i.e. if you are using ml in an equation keep using ml even one of the variables is in litres)

If you just want to know how many cells you have use V=N/C where N= number. Same equation used for making chemical solutions in the lab!

bio08 on Apr 14 2010, 05:27 AM said:

I centifuge my cells and dissolve the pellet in 5 ml media.

In this 5 ml cell suspension I counted the cells and I have 0,95 mil cells/ml

I need 0,5 mil cells/ml in total volume 1,5 ml

So 1,5 ml * 0,5 cells/ml=0,75 mil cells/ml

0,75 mil / 0,95 mil = 790 ul I will take from my 5 ml cell suspension and add 710 ul media to get 1,5 ml total volume

Is this calculation right?

Thank you very much again!

Yes, U r right.

U started with 5 ml of 0.95 million cells/ml which has 4.75 million cells in total (0.95 X 5). U needed to make 1.5 ml of 0.5 million/ml cell suspension which will require 0.75 million cells (1.5 X 0.5). 0.75 million cells are in 0.789 ml of the cell suspension U had < (0.75/4.75) X 5 >.

So, U took 0.789 ml from the cell suspension U had (which will have 0.75 million cells) and to make 0.5million/ml cell suspension, U needed to add 0.711 ml of medium (1.5-0.789)