[Curiousjack]

Hi,

I'm not sure if I'm in the right forum or not, but here is my question. When you are talking about artificial hormones, such as testosterone, and the concentration of the hormone in the solution, does the dosage (example, 100mg/ml) translate to real weight?

For example, if I have a 10ml bottle of testosterone in a solvent and it is dosed at 100mg/ml (total 1000mg), and another 10ml bottle that is dosed at 250mg/ml (total 2500mg). Assuming everything else was equal, if I weighed the 2 bottles, would the 250mg/ml bottle weigh 1500mg more than the other bottle??

[Borek]

No, it doesn't work this way.

First of all - what about the bottle weight?

Second - 100 mg per mL doesn't mean 1 mL weighs 1.1 g, just like 250 mg per mL doesn't mean 1 mL weighs 1.25 g.

Somehow 100 mg per mL looks quite high to me.

[Curiousjack]

No, it doesn't work this way.

First of all - what about the bottle weight?

Second - 100 mg per mL doesn't mean 1 mL weighs 1.1 g, just like 250 mg per mL doesn't mean 1 mL weighs 1.25 g.

Somehow 100 mg per mL looks quite high to me.

Yes but as I said assuming all other things were equal, like the weight of the 2 bottles, the weight and volume of the solvent etc... The only difference between the 2 bottles is the actual concentration of hormone in them.
So if the total amount of hormone in one bottle is 2500mg, and in the other it's 1000mg, does this mean they will have a weight difference of 1500mg (2500-1000)?

[Borek]

Assuming all other things being equal, then yes, that should be the difference.

But don't count on everything else being identical - I mean, while in theory that's OK, it won't work in practice.

[Corribus]

This would assume an ideal solution, which they probably aren't. Also, it depends on how you make your solution. E.g., if you put the solid in a vial and add solvent until you get 100 mL, it's different than if you put the solid in the vial and add 100 mL solvent. That is, your concentration is xx mg / 100 mL solution vs. xx mg / 100 mL solvent. That's an important distinction if the amount of solute is large.

[Bidagdha_TADIR]

I agree with Corribus. Let's consider two solutions -
1. 50% w/w sucrose solution (molarity = 1.796 mol L^-). It has a density of 1.2295 g cm^-3. We can also express the concentration of this solution as
             (1.796×342)g/L = 614.232g/L = 614.232mg/mL
   Since the density of this solution is 1.2295, the weight of 10mL of this solution is 12.295g.
2. 60% w/w sucrose solution (molarity = 2.255 mol L^-). It has a density of 1.2864 g cm^-3. We can also express the concentration of this solution as
              (2.255×342)g/L = 771.21g/L = 771.21mg/mL
   Since the density of this solution is 1.2864, the weight of 10mL of this solution is 12.864g.

So 10mL of sucrose solution having concentration of 614.232mg/mL has a weight of 12.295g and 10mL of sucrose solution having concentration of 771.21mg/mL has a weight of 12.864g. Now, the difference between the amount of sucrose present in 2nd solution and the amount present in first solution is
          (771.21×10)-(614.232×10) = 1569.78mg=1.56978g

But, the difference of weight of two solution is (12.864-12.295) = 0.569gm.

So, the weight difference between the 100mg/mL bottle and 250mg/mL bottle wouldn't be 1500mg, it will probably be less. But this will depend on how much testosterone interacts with water (not chemical reaction).

(The density data is taken from "Handbook of chemistry and physics" - 89th edition).