# Protein measuring - (Sep/09/2005 )

When I make the standard curve then each standard solution is prepared like this:
800ul water
20ul each standard solution
200ul dye concentrate

The samples are prepared like this:
800ul water
4ul each sample solution
200ul dye concentrate

I wonder if I for instance get 0.5mg/ml on one of my sample. Does this mean that this value is the concentration of the original sample or should I multiply with 5 since the volume of the standard is larger (20ul) then the volume of the sample (4ul)?

-seasons-

When you calculate Absorbance(sample) dived by Absorbance(standard) multiplied by concentration of the standard, then you also have to multiply by 5.

-Theo22-

QUOTE (Theo22 @ Sep 9 2005, 09:42 AM)
When you calculate Absorbance(sample) dived by Absorbance(standard) multiplied by concentration of the standard, then you also have to multiply by 5.

What do you mean with divide absorbances between sample and standard? what i do is; from the standard curve then i get the concentration of a sample by its absorbance and this value can be for instance 0.5mg/ml. I wonder is this value also the concentration of my original sample or should i multiply this value with 5 since the volume of the standard is 5X larger than the volume of the sample?

-seasons-

What you are doing is exactly the same as I was saying, execpt that you are reading from the graph and I was calculating.
If you put on the (X or Y) axis the concentration for the standaard solutions without correction for the 5 times more volume, then ofcourse you still have to correct the results of your sample by multiplying by 5.

-Theo22-