BSA Standard Curve Dilution (BCA Kit) - how to dilute the correct way? (Jun/11/2010 )

Hi,

the Pierce BCA Kit comes already with Albumin Standard Ampules, 2 mg/ml, diluted in a solution of 0.9% saline and 0.05% sodium azide that are used for the Preparation of Diluted Albumin Standards.
As you know, the standard should be diluted in the same buffer as the sample. Let´s say the sample is diluted in RPMI or any other medium - you are advised to use the same medium for your diluted albumin standards.
My problem is: When you do a series of a 1:2 dilution, there will be always 50% salt solution and 50 % medium for every standard except the 2mg/ml beginning standard that has 100 % salt solution (ok, for the lower standards the salt solution will be diluted out but something is still there). On the one hand, there will be less background signal measured (assumed that there is one) compared to the samples that are in 100% medium. On the other hand, you have to subtract the blank (medium) from your standards that is nonsense for your highest standard (2 mg/ml) because it isn´t diluted in medium.

Hope you get my point!

I dilute the standard with Saline 0.9% and have no concern about the matrix of my samples because I assume the the fact that in the samples a mix of protein are present and not only albumin as in the standard this will have more influence on my results.

What you mean by saline, PBS?????

Gerard on Jun 12 2010, 08:24 AM said:

I mean just NaCL 9g/l but PBS will do to.

I see, thanks!

Gerard on Jun 14 2010, 02:52 PM said:

medchemgirl on Mon Jun 14 20:44:18 2010 said: