Hi all,

I have a question about a calculation I am struggling to solve. I have two mix two different antibiotic solutions..one at 50mg/ml and the other one at 10mg/ml . The final solution of the mix of the two antibiotics should be at 10 mg/ml...How do I calculate the initial volumes to take from the two stock solutions to mix?

Thank you in advance.

Silvia

Unless you've made a typo, it isn't possible with those concentrations. Anything you add to the 10 mg/mL solution will dilute it; you're not able to have both antibiotics at 10 mg/mL with these stocks unless you add the other one as a solid or make up a different concentration of the 10 mg/mL one. I would recommend the latter.

 

To answer your math problem with different stocks, let's say were making up a solution with two stocks of 50 mg/mL and need to get to an final concentration of 10mg/mL. Each would need to be diluted 1:5, so I would simply add 20 or 200uL of each and make up to 100 uL or 1000 uL respectively, depending on how much you have / need.