# concentraion measurement - (Jun/11/2009 )

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Hi,

I have a protein solution whcih is at a concentration of 50nmoles/gram ( as told by my senior). I am not sure what this means as it is nmoles/gram. Iam only used to working in nmoles/ml or ul , but I cnat understand what nm/gram mean? Can someone explain me this and also tell me what will be the fianl concentration ( in moles) of the same protein solution if Iam going to aliquot 30uL (Mw of protein= 10000). I need help from someone as my senior is not very kind.

Thanks
rax

-rax-

rax on Jun 11 2009, 04:11 PM said:

Hi,

I have a protein solution whcih is at a concentration of 50nmoles/gram ( as told by my senior). I am not sure what this means as it is nmoles/gram. Iam only used to working in nmoles/ml or ul , but I cnat understand what nm/gram mean? Can someone explain me this and also tell me what will be the fianl concentration ( in moles) of the same protein solution if Iam going to aliquot 30uL (Mw of protein= 10000). I need help from someone as my senior is not very kind.

Thanks
rax

Have you never used Xmoles per gram?

Ex 5 mol/gr simply means that you have 5 moles for each gram you take...
The n simply means nanomols...

and if you take 30µl it depends on how much gram you diluted in the 30µl..

ex calculation:

You have 10 nmol/ gram and you need a 30nmol/liter solution

then you need to take 3 grams and dilute this in 1 liter of water.
(if the 10nmoles refer to the 1 substance you need, I do not know what is in your product)

maybe you should give some more information, I do suppose your product is a powder, not a liquid? If it is a liquid you need to know the density of the liquid how many grams/ml)

-pito-

Hi Pito,

Thanks for posting back. My substance is a liquid, and the details I metioned are the only details my senior gave and told me will be fine to finish the calculations. He also mentioned that the final answer will be 1.5nmoles ( ie in the aliquotted 30uL ). Iam still not convinced how I could come to this answer and Iam sure he is right.

could you explain this to me.

Thanks,
rax

pito on Jun 11 2009, 07:21 AM said:

rax on Jun 11 2009, 04:11 PM said:

Hi,

I have a protein solution whcih is at a concentration of 50nmoles/gram ( as told by my senior). I am not sure what this means as it is nmoles/gram. Iam only used to working in nmoles/ml or ul , but I cnat understand what nm/gram mean? Can someone explain me this and also tell me what will be the fianl concentration ( in moles) of the same protein solution if Iam going to aliquot 30uL (Mw of protein= 10000). I need help from someone as my senior is not very kind.

Thanks
rax

Have you never used Xmoles per gram?

Ex 5 mol/gr simply means that you have 5 moles for each gram you take...
The n simply means nanomols...

and if you take 30µl it depends on how much gram you diluted in the 30µl..

ex calculation:

You have 10 nmol/ gram and you need a 30nmol/liter solution

then you need to take 3 grams and dilute this in 1 liter of water.
(if the 10nmoles refer to the 1 substance you need, I do not know what is in your product)

maybe you should give some more information, I do suppose your product is a powder, not a liquid? If it is a liquid you need to know the density of the liquid how many grams/ml)

-rax-

rax on Jun 11 2009, 05:26 PM said:

Hi Pito,

Thanks for posting back. My substance is a liquid, and the details I metioned are the only details my senior gave and told me will be fine to finish the calculations. He also mentioned that the final answer will be 1.5nmoles ( ie in the aliquotted 30uL ). Iam still not convinced how I could come to this answer and Iam sure he is right.

could you explain this to me.

Thanks,
rax

pito on Jun 11 2009, 07:21 AM said:

rax on Jun 11 2009, 04:11 PM said:

Hi,

I have a protein solution whcih is at a concentration of 50nmoles/gram ( as told by my senior). I am not sure what this means as it is nmoles/gram. Iam only used to working in nmoles/ml or ul , but I cnat understand what nm/gram mean? Can someone explain me this and also tell me what will be the fianl concentration ( in moles) of the same protein solution if Iam going to aliquot 30uL (Mw of protein= 10000). I need help from someone as my senior is not very kind.

Thanks
rax

Have you never used Xmoles per gram?

Ex 5 mol/gr simply means that you have 5 moles for each gram you take...
The n simply means nanomols...

and if you take 30µl it depends on how much gram you diluted in the 30µl..

ex calculation:

You have 10 nmol/ gram and you need a 30nmol/liter solution

then you need to take 3 grams and dilute this in 1 liter of water.
(if the 10nmoles refer to the 1 substance you need, I do not know what is in your product)

maybe you should give some more information, I do suppose your product is a powder, not a liquid? If it is a liquid you need to know the density of the liquid how many grams/ml)

I really cant see how to calculate this if you have no relation (density) given between mass and volume(liter)

-pito-

If the solvent is water (which is often the case with proteins) you can mostly get away with the relation 1 g = 1 ml, thus you'd have 50 nmol/ml. But, it seems like a weird unit to provide a concentration in. Are you sure you're senior didn't simply misspeak?

-SatanClaus-

I do wonder how you should have done it, because its just not really possible.

-pito-

just put your 30uL on a scale:

If your solution has x Mol / gram and after pipetting 30uL into another tube, that tube weights x gram, how many moles do you have now?

-warsel-

Hi guys, I've been reading every post on this topic, and the more I read it the more confused I get. It's defying all biochemistry laws, and definitely defies all my understanding of concentrations and molecular weight.

rax says the protein solution is at 50nmol/gram.
He/she also says the protein MW is 10,000.

Now, by definition MW = grams of a molecule (protein in this case) per mol. So, it is impossible to have 50nmol in 1 gram of protein, if its molecular weight is 10,000. So, either you have 0.1µmol in 1 gram of protein (0.1µmol/gram according to its MW), or the protein has a molecular weight of 20,000,000 (for it to possibly be 50nmol/gram).

Am I going crazy here, or just missing something?

I agree with SatanClaus and pito, it has to be a mistake, as it is just NOT possible.

-almost a doctor-

You are missing that the SOLUTION of the protein weights 1 gram and this solution contains 50nM protein and the rest is presumeably water.

If 1g of a solution has 50nMoles, how many moles does 30uL of that solution have:

Accurate way:
Weight 30uL of that solution on a scale, calculate:

50 nMoles / 1g * (weight of 30uL in grams) = nMoles of 30uL solution

Approximation:
Water has a density of 1 kg/L, 50nMoles protein is a negligible weight (1 Mole = 10,000g -> 50n Moles = 500µg)

Therefore 50nMoles in 1mL: 50nMol / 1000µL * 30µL = nMoles of 30uL solution

Please note that the result is NOT a concentration - the original poster confused Molarity with Moles i suppose. The concentration is of course the same as before aliquoting.

-warsel-

warsel on Jun 18 2009, 12:59 PM said:

You are missing that the SOLUTION of the protein weights 1 gram and this solution contains 50nM protein and the rest is presumeably water.

If 1g of a solution has 50nMoles, how many moles does 30uL of that solution have:

Accurate way:
Weight 30uL of that solution on a scale, calculate:

50 nMoles / 1g * (weight of 30uL in grams) = nMoles of 30uL solution

Approximation:
Water has a density of 1 kg/L, 50nMoles protein is a negligible weight (1 Mole = 10,000g -> 50n Moles = 500µg)

Therefore 50nMoles in 1mL: 50nMol / 1000µL * 30µL = nMoles of 30uL solution

Please note that the result is NOT a concentration - the original poster confused Molarity with Moles i suppose. The concentration is of course the same as before aliquoting.

Thanks warsel... now it makes sense

-almost a doctor-
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