How to express concentration of organic compound?

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

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Hi

I am using v/v % to express concentration of my analytes in solution. I am adding 40uL of 16 different analytes (purity ranges from 95% to 99,9% with average of 99,2%) and diluting a solution to 800uL with acetonitril.

So, calculation is v/v % (per analyte) = 40uL x 99,2% / 800uL = 4,96%

How to calculate a concentration of each analyte if I took 40 uL from 4,96% solution and diluted it to 800uL with acetonitrile again.

Is it again: v/v % (per analyte) = 40 uL x 4,96% / 800 uL = 0,284%? Am I doing something wrong?
studentjelena wrote:
Hi

I am using v/v % to express concentration of my analytes in solution. I am adding 40uL of 16 different analytes (purity ranges from 95% to 99,9% with average of 99,2%) and diluting a solution to 800uL with acetonitril.

So, calculation is v/v % (per analyte) = 40uL x 99,2% / 800uL = 4,96%

How to calculate a concentration of each analyte if I took 40 uL from 4,96% solution and diluted it to 800uL with acetonitrile again.

Is it again: v/v % (per analyte) = 40 uL x 4,96% / 800 uL = 0,284%? Am I doing something wrong?


800ul / 40ul = 20 dilution factor, so take 4.96%/20=0.248%

So yes, just divide all the separate concentrations by 20 and you have the new concentration.

Easiest way to do dilutions is take:

Initial concentration / (Final volume / Aliquot volume) = New Concentration
The past is there to guide us into the future, not to dwell in.
Thank you for your kind confirmation.


Have a good day
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