Drug dissolved in DMSO question

Question

I need to make a 1000x stock solution from 1g of MPTP. This stock solution has to be stored in a 1ml eppendorf tube. I want to have a 7.5M stock solution that I can dilute down to 7.5mM when needed. So far this is what I have calculated:

MW MPTP: 171.15g/mol

MPTP (powder): 1g (I have a 5g bottle I'm only going to use 1g)

7.5mM = 7500mM or 7.5M (1000x stock)

1g/171.5g/mol = 0.00584283mol

Volume (L) = amount in mol/concentration (M)

= 0.00584283mol/7.5Mole per L

0.00077904 L = 0.77904 mL = 779.04 ul

1g MPTP dissolved in 779.04ul DMSO (0.1%)? I need to have 1g MPTP dissolved in DMSO at 0.1% but i'm not sure if im final answer reflects that. Is there another way to calculate this?

Answer 1

If we use a molar mass of MPTP of 171 g / mole ...

To prepare a solution that is 7.5 mM, we need 7.5 mmol / L or 7.5 umol / ml

To prepare 1 ml then, we would need 7.5 umoles.

7.5 umols x 171 ug / umole = 1283 ug = 1.283 mg = 1.3 mg dissolved in 1 ml = 7.5 mM MPTP

If you wanted to make a 1000x stock (perhaps it is more stable), then you would need 1.3 g in 1 ml. I seriously doubt you would be able to dissolve that. How about a 10x stock, or 100x stock.

From 10x stock, dilute 1:10 to get 7.5 mM and 10% DMSO

From 100x stock, dilute 1:100 to get 7.5 mM and 1% DMSO

This is the best answer I can give for now without knowing more about exactly what your desires are. Hope this helps. Good luck.