Hi,

You can simply use the dilution law C1V1=C2V2 where C1 is the concentration of your ampiciline solution (i.e. 200 mg/ml), C2 is the final concentration of the diluted ampiciline solution (i.e. 0.04 mg/ml), V2 is the total volume (i.e. 300 ml) and V1 is the is the sought volume to add. So V1 = C2V2/C1.

N.A: V1=0.04*300/200. V1=0.06 ml that’s mean 60 µl. However, if you are not yet prepared your stock solution, I suggest you preparing a new stock with 12 mg/ml (12 g/l) to get a more accurate measured V1 volume (1 ml after calculation).

Concerning your second question, the dilution time D means the total solution (i.e. 75 ml) volume per the added volume (D=Vtotal/Vadd), so Vadd ( bacterial volume in ml) = Vtot/D. N.A: Vadd = 75/50. V add=1.5 ml this means that you should add 1.5 ml of bacteria and complete to 75 ml with your medium.

Regards

I agree with @Bilal Zinati for only the first question. However, for the second question, you can apply the following equation:

Dilution factor = (aliquot + diluent)/aliquot

It means that:

50=(aliquot+75)/aliquot

So,

aliquot = 75÷49=1.53 ml.

It means that you need to add 1.53 ml of your bacteria to 75 ml of medium. So you will obtain 76.53 ml as a final volume.

Duried Alwazeer Bilal Zenati thank you!!

I agree with Professor Duried Alwazeer if you meant that the total volume is aliquot + 75 ml.

Hi Zuzanna,

You may use the web tool to calculate

https://www.alfa-chemistry.com/solution-dilution-calculator.htm