[xJohnKnox]

Hi, everyone
Thanks for stopping by if you're here. It means a lot.

I'm a PhD student, and I'm trying to solve a problem for a neuro experiment on frogs.

I am trying to inject 150nL into frogs. I need that 150nL to have 20nmoles of a compound in it.

The compound has a molecular weight of 230.13.

I'm trying to figure out how much of the compound I need to dissolve into 1mL to get a 20nmole/150nL dose. And, what would the resulting molarity of this solution be?

Thanks for all your help.

[Babcock_Hall]

Can you show your calculations so far?

[xJohnKnox]

Thanks for replying.

My calculations are kind of all over the place...

I think I need 0.030684g in a 1 mL solution to get my desired dose + solution. I found this because 20nmole of the compound is 4.6026 micrograms. So, then I set up proportions and worked them out. I think this is a 133 micromolar solution.

[Babcock_Hall]

One has to be careful about units and cancelling units correctly.  How did you get 133 µM?  I obtained a different number.  Your calculation of mass looks OK, but I solved it differently.

[xJohnKnox]

Ah—I think I had a zero in there somewhere. The molarity should be 133 mM.

I found this using a calculator on Sigma Millipore.

[Babcock_Hall]

That was also the concentration that I found.

[xJohnKnox]

Thanks a lot. This forum is great!

[jeffmoonchop]

Normally you would inject a dose based on the mass of the organism. For more reproducible results.