September 12, 2024, 12:31:24 PM
Forum Rules: Read This Before Posting

0 Members and 1 Guest are viewing this topic.

#### xJohnKnox

• New Member
• Posts: 4
• Mole Snacks: +0/-0
« on: March 08, 2022, 06:59:12 PM »
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?

« Last Edit: March 09, 2022, 02:26:02 AM by sjb »

#### Babcock_Hall

• Chemist
• Sr. Member
• Posts: 5671
• Mole Snacks: +328/-24
« Reply #1 on: March 08, 2022, 07:16:18 PM »
Can you show your calculations so far?

#### xJohnKnox

• New Member
• Posts: 4
• Mole Snacks: +0/-0
« Reply #2 on: March 08, 2022, 07:25:33 PM »

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

• Chemist
• Sr. Member
• Posts: 5671
• Mole Snacks: +328/-24
« Reply #3 on: March 08, 2022, 07:36:21 PM »
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

• New Member
• Posts: 4
• Mole Snacks: +0/-0
« Reply #4 on: March 08, 2022, 07:40:48 PM »
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

• Chemist
• Sr. Member
• Posts: 5671
• Mole Snacks: +328/-24
« Reply #5 on: March 08, 2022, 08:23:47 PM »
That was also the concentration that I found.

#### xJohnKnox

• New Member
• Posts: 4
• Mole Snacks: +0/-0
« Reply #6 on: March 08, 2022, 08:27:07 PM »
Thanks a lot. This forum is great!

#### jeffmoonchop

• Full Member
• Posts: 334
• Mole Snacks: +37/-5
• Gender: