How to dilute a lyophilized substance? - (May/29/2008 )

I have an agent I will be treating my cells with. How do you go about diluting a lyophilized substance. Say it is 1mg and the MW is 345 and I want my final stock concentration to be 400uM. I need a formula and can't figure one out.

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Making solution from a lyophilized substance is as good as making any solution from any solid chemical (ie, NaCl, Tris..). As long as you know the MW.

making solutions: http://search.vadlo.com/b/q?keys=making+so...mp;sn=158621799

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is it a 1. pure lyophylizate or 2. lyophylized wiith salt and buffer components? you need 1. water/buffer or 2. only water

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I know I have to use DMSO. I just don't know how to figure out how much to use.

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o.k., a lipophilic product...; is it a known substance? you may find minimum solubility in Merck index or homepages of Sigma-Aldrich, Calbiochem, Merck or other biochemistry companies

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Dear Calla,

The general rule I use is: for example:

MW 100.

1mg in 10 mls = 1mM


Therefore your MW is 345

Same rule: 3.45mg in 10mls = 1mM

You have 1mg, therefore this should be diluted in 2.89 mls to give 1mM

You could dilute it in 0.289 mls...this would give you a higher stock concentration of 10mM

Either way to get your required 400uM, then 1mM needs to be diluted 1:2.5

or your 10mM stock solution needs to be diluted 1:25

Hope this is useful

Kindest regards

Rhombus

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Thank you Rhombus! Can you please explain how you got 2.89 mls? Sorry, I am really not good at this.

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