As per literature LOD is calculated using equation LOD = k (Sy/S). Where, Sy is standard deviation of blank value, S is the sensitivity of immunosensor, and k (k=3) is the confidence level factor. I have a doubt about performing experiment for blank reading. In my case, analyte (antigen) is a part of modified electrode. Here I use H2O2 in electrolyte. My question is how to run a blank experiment. Whether not to use an analyte in modified electrode or run measurement with the lowest conc. of analyte in electrode without H2O2 in electrolyte?
There is more than one way to determine the "blank" value, and as with most things, the method with more integrity is generally more laborious. If I were you, I would definitely run an experiment with no analyte on your electrode while keeping H2O2 in the electrolyte, because changing the electrolyte will definitely confound the validity of your result. If the antigen is added to your electrode early in the procedure, that might seem an awkward omission to make, but in that case it would never become a commercially-viable sensor anyway.
Because of the arms race over limit of detection, many researchers cheat when they calculate this figure, both experimentally and mathematically. As a peer reviewer, I'm skeptical of this figure and much more interested in repeatability - how many sensor repeats were done - and the lower limit of linear detection.
Sunil Patil You might be interested in this blog post that discusses extensively the importance (and role) of the blanks in measuring a limit of detection: https://raphazlab.wordpress.com/2021/12/16/down-the-rabbit-hole-of-the-limit-of-detection-lod/
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