Hello Tolulope Falana

Good day to you.

You may make 10mM stock solution of all trans retinoic acid (ATRA) in DMSO.

Molecular weight of all trans retinoic acid (ATRA) is 300.44 g.mol-1 ·

You may go about as follows:

1M--------300.44g---- 1Litre

0.01M-----3.004g------ 1000ml

10mM----- 0.00300g------- 1ml

10mM----- 3mg------------- 1ml

So, you will have to weigh 3mg ATRA in 1ml DMSO to obtain a stock of 10mM in DMSO.

Then you may make use of the formula

C1V1=C2V2

Where,

C1= concentration of stock (10mM)

V1= volume of stock to be taken (Xml)

C2= concentration of working solution (10μM)

V2= volume of working solution (say 1ml)

10mM x X ml = 0.01mM x 1ml

X= 0.01 x 1/ 10 = 0.001ml = 1μl

So, you will have to add 1μl of stock solution (10mM) to 999μl of culture media to give you 10μM working solution in 1ml.

However, 1μl is too less a volume to pipette which may lead to pipetting error. Therefore, you may dilute the stock 1:10 with culture media to obtain a diluted stock of 1mM. Add 10μl of the diluted stock to 990μl of culture media to obtain 10μM working solution in 1ml.

Similarly, for 50μM of ATRA working solution use the above formula.

C1V1=C2V2

Where,

C1= concentration of diluted stock (1mM) which is already prepared

V1= volume of diluted stock to be taken (Xml)

C2= concentration of working solution (50μM)

V2= volume of working solution (say 1ml)

1mM x X ml = 0.05mM x 1ml

X= 0.05 x 1/ 1 = 0.05ml = 50μl

So, you will have to add 50μl of the diluted stock solution (1mM) to 950μl of culture media to give you 1ml of 50μM working solution.

Meanwhile, you will have to keep the DMSO concentration equal to or less than 0.1% in the final solution that you add to the cells in order to avoid toxicity caused to the cells due to DMSO. In both cases (10μM and 50μM of ATRA working solution), if you follow the above calculations, the DMSO concentration will be 0.1%.

Best.

Thank you so much Malcolm Nobre