# concentraion measurement

### #1

Posted 11 June 2009 - 06:11 AM

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

### #2

Posted 11 June 2009 - 06:21 AM

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)

**Edited by pito, 11 June 2009 - 06:22 AM.**

### #3

Posted 11 June 2009 - 07:26 AM

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

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)

### #4

Posted 11 June 2009 - 08:12 AM

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,

raxHi,

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)

### #5

Posted 11 June 2009 - 01:20 PM

### #6

Posted 17 June 2009 - 08:50 AM

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

### #7

Posted 18 June 2009 - 01:57 AM

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?

### #8

Posted 18 June 2009 - 02:38 AM

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.

### #9

Posted 18 June 2009 - 03:59 AM

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.

### #10

Posted 18 June 2009 - 06:06 AM

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

### #11

Posted 18 June 2009 - 11:02 PM

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?

Indeed,

didnt think about that.

He can indeed do it like this.