The standard curves for all of the trials for this experiment have had R^2 values of above 0.9. I need to determine whether this is acceptable or whether I need to troubleshoot and improve my technique for more precise results. I have been using an R&D Systems PGE2 ELISA kit.
R^2 should be as close to 1 as possible. 0.9 is relatively low. This could just be due to pipetting error.
Hi Laura
I have attached the typical PGE2 standard curve given by R&D Systems on their website (assuming this is the same kit you are using). On a log scale the working range is still slightly sigmoidal in shape. I assume you are fitting a polynomial curve of some description to give the best fit to your calibration standards? If you are fitting a linear regression line to these standards it would explain a low R^2 value.
However, even if you are correctly fitting a polynomial curve to your standards, I would still be happy with R^2 being consistently above 0.9. You have proven by repeated trial runs that the kit is reasonably reproducible with respect to R^2 - this consistency is more important than the accuracy of your fit. While we have not used PGE2 kits, in our experience R^2>0.9 for an immunoassay is perfectly acceptable. It is more important to assess the accuracy of the kit in quantifying concentrations in your control samples.
Since this is a kit with pre-prepared reagents, there is little troubleshooting you can do other than proper storage, ensuring your plate washing is consistent and thorough and, as mentioned by Charles, that your pipetting technique is as good as possible.
Best of luck.
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