Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

When we draw a calibration curve for single radial immunodiffusion, the curve does not pass through origin. Instead, there is a y intercept. Why does that happen ? Shouldn't zero antigen give zero ring diameter ?

share|improve this question

1 Answer 1

up vote 3 down vote accepted

When the radial immunodiffusion method is used to measure antigen concentrations in samples, a plate or slide is set up using agarose containing an antibody or antiserum. Holes are punched out of the agarose to form wells into which antigen is dispensed. The antigen diffuses out into the agarose and when the antigen/antibody ratio is favourable an immunoprecipitate will form as a ring (immunoprecipitin ring). The final diameter of the ring is proportional to the initial concentration of antigen.

Addressing the question: isn't this simply explained because the values on the Y axis are squares of the diameters of the rings, and this includes the well into which the antigen is dispensed?

share|improve this answer
    
Thanks ! I thought the diameters were taken from edge of the ring. –  biogirl Jun 28 at 17:51

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.