Protocol Online logo
Top : New Forum Archives (2009-): : ELISA and Immunoassay

Background variation - (Mar/31/2011 )

I ran a bunch of blank samples in a plate and noticed that towards the end of the plate samples are having a higher background then samples at the beginning of the plate. For example the blanks in wells A1 and A2 average ~0.058 optical density while H9 amd H10 ~0.083. What could be responsible for this? Thanks.

Best,

Grad

-Gradstudent78-

What is your %CV of replicates? Could be assay variability, carry over, manual v. automated washing, insufficient washing etc.

-PAO_ahac-

PAO_ahac on Thu Mar 31 12:27:28 2011 said:


What is your %CV of replicates? Could be assay variability, carry over, manual v. automated washing, insufficient washing etc.


%CV for replicates are all < 10%. I use an automated 4x washing.

-Gradstudent78-

does your reader read the whole plate at once or does it read a row at a time?

do you kill the color reaction or just read it?

if the reader does a row at a time and you don't kill the reactions (all at the same time) then the reaction continues during reading.

-mdfenko-

mdfenko on Thu Mar 31 16:27:38 2011 said:


does your reader read the whole plate at once or does it read a row at a time?

do you kill the color reaction or just read it?

if the reader does a row at a time and you don't kill the reactions (all at the same time) then the reaction continues during reading.


Not sure about the reader (it's fairly old, probably going to buy a new one soon), but we do use a stop solution to kill the reaction.

-Gradstudent78-