Question

i have 1.36x10^7 cells/mL and i need to perform a serial dilution to get 1.0x10^6/100 microliters. how is this done?

Answer 1

From the question,

We have 1.36 x 10⁷ cells/ml (Initial concentration)

We need diluted suspension having 1.0 x 10⁶ cells/100µl.

As we know that, 1 ml = 1000 µl

Therefore initial concentration = 1.36 x 10⁷ cells/1000 µl i.e. 1.36 x 10⁶ cells/100 µl

Let us assume, we need to have 1000 µl of suspension with the concentration of 1.0 x 10⁶ cells/100µl.

We can use the formula N1V1=N2V2

Where N1 = Initial concentration (1.36 x 10⁶ cells/100 µl)

             V1 = Volume which we need to take from original stock to get the desired diluted concentration

             N2= Final concentration (1.0 x 10⁶ cells/100µl)

             V2= Final volume (1000 µl)

Feed these values in the formula

                        N1V1 = N2V2

                       1.36 x 10⁶ cells/100 µl x V1 = 1.0 x 10⁶ cells/100µl x 1000 µl

                       V1= (1.0 x 10⁶ cells/100µl x 1000 µl)/1.36 X10⁶ cells/100 µl

                            = 0.735 x 1000 µl = 735 µl

Therefore, take 735 µl of cells from original stock (i.e. the suspension having cell concentration 1.36 x 10⁷ cells/ml) and add to the 265 µl of buffer or appropriate diluent. This dilution would have a concentration of 1.0 x 10⁶ cells/100 µl