# How to convert dimensions? - (May/31/2012 )

I feel ashamed of this idiotic post but nobody has ever teached me this and I need to elucidate it once forever:

1. Molar concentration reffers to g/L (i.e.one FW (g/mol) in 1 liter), and hence milimolar is mg/mL, micromolar in ug/uL, etc. - Yes or No?

2. When we measure concentration and the mashine gives a dimension ug/mL but our stock solution is in microliters, then we convert the result in ng/uL - Yes or No? In the same logic, if recommended concentration of something is 50 ug/mL but the volume of reaction is in uL we apply 50 ng/uL - Yes or No?

3. The capital ''M'' in the dimension uM is reffered to Liter and means ug/L - Yes or No? So, if recommended concentration of something is 1 uM (1 ug/L) but volume of reaction is in microliters then we apply 1 picogram/uL of this reagent - Yes or No?

I would highly appreaciate if somebody dedicate some amount of time and control this fo me.

Thank you.

-Nephrite-

Okay, so the first thing is your definition of Molar is wrong. Molar = n / liter where n is the number of moles. So 1 M = 1 mole / L
Moles= gr/ MW but molar is not = g/L

Nephrite on Thu May 31 09:12:51 2012 said:

1. Molar concentration reffers to g/L (i.e.one FW (g/mol) in 1 liter), and hence milimolar is mg/mL, micromolar in ug/uL, etc. - Yes or No? The decisive factor is the volume, not the amount - Yes or No?

NO first you have it wrong for the reason explained above M=mol/L NOT g/L

Furthermore, by definition M is the number of moles in a L so: molar=mole/L , milimolar=milimole/L, micromolar=micromole/L .... The decisive factor IS the amount. http://en.wikipedia.org/wiki/Molar_concentration here's a good explanation (although gets a bit confusing with talking dm3 instead of Liters).

2. When we measure concentration and the mashine gives a dimension ug/mL but our stock solution is in microliters, then we convert the result in ng/uL - Yes or No? In the same logic, if recommended concentration of something is 50 ug/mL but the volume of reaction is in uL we apply 50 ng/uL - Yes or No?

Yes. The best way is to always keep your units consistent.

3. The capital ''M'' in the dimension uM is reffered to Liter and means ug/L - Yes or No? So, if recommended concentration of something is 1 uM (1 ug/L) but volume of reaction is in microliters then we apply 1 picogram/uL of this reagent - Yes or No?

NO. again, M -> Molar=moles/L uM=micromolar=micromoles/L so if the reaction is in microliters you'll be talking picomoles.

I would highly appreaciate if somebody dedicate some amount of time and control this fo me.

Thank you.

Hope this helps and I haven't confuse you even more.