pM from uM

Questions and answers on how to convert things from one unit or system to another


pM from uM

Postby JIG » Fri Oct 07, 2005 12:02 am

I swear I am not defecient, but I have made it halway through grad school without knowing how to convert uM solutions into pM solutions. I have a 100uM stock soln, and need a 50pM soln. I have tried 2-3 math conversions which had my confidence at the time only for sore dissapointment after a 3 hour thermal-cycler run. What if I add my pM soln. to a reaction, does that make it even more dilute, like nM? Whimper.

Postby Guest » Fri Oct 07, 2005 1:07 am

If you have an initial concentration and volume C1 and V1, and you dilute it with pure water (or whatever the solvent is) to a new total volume V2, the new concentration is C2 where

C1 * V1 = C2 * V2
(the added solvent is approximately (V2 - V1)

so V2 = C1 * V1/C2 = 100 uM * V1/ 50 pM
= 2x10^6 * V1

added solvent = V2 - V1 = 1,999,999 * V1
(very dilute!!!)

micro = 10^(-6), nano = 10^(-9), pico = 10^(-12), so a nM solution is strong than a pM solution.

Postby JIG » Fri Oct 07, 2005 2:39 am

Yeah, that was one of the formulas I thought I had tried. So let's say I am working in uL. According to that formula (I think), then 2 uL of my 100uM soln. into 98 uL water? Wouldn't that give me a 2 pMol soln.? 20? 200? I tried 1 uL into 999 uL yesterday, that did not work.

Postby Guest » Fri Oct 07, 2005 2:55 am

If you really want 50 pM solution, you have to dilute it to 2 million times greater volume. So 2 uL needs to be diluted to 4 L.

But I can't believe you want that dilute a solution; you may want to doublecheck the required concentration

Postby JIG » Fri Oct 07, 2005 11:00 pm

Hey man, that's just what I am reading off the protocol. But I think you are right in essence. I am going to work in the uM range and just take it down to 5 or so and give that a shot. Thanks for confirming how insanely dilute that would be. Off to take initiative on the concentrated molecular bio front.

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