Hello.. the LOQ many times is 10 times the standar deviation of the blank..while the LOD is usually 3 times the standar deviation of the blank. Do not use current to built the calibration curve because it has the time as a variable..the correct method is to plot Concentration vs Charge and no Concentration vs Current.
Thank you so much for your reply. Actually, I have calculated the LOD (µM) of an electrochemical sensor by S/N=3 method. Now I want to calculate the error limit and LOQ. Is there any method to calculate by this way?
I used an electrochemical cell where a buffer was used as supporting electrolyte with an analyte (which to be detected).
In case of ''standar deviation of the blank'', did you mean ''standard deviation of noise of buffer''?? Buffer gave no peak but noise could be calculated.
In case of ''no Concentration vs Current''___ Sorry dear. I didn't understand.
What i meant is that in many research papers people plot for the calibration curves y= Current (I) and x= concentration (M).. But this is not really a good practice.. people should plot y= charge and not current because is charge what can be related directly to concentration and no current.. thats just something to have in mind.. Now about the standar deviation of the blanck.. even when you have no peaks in the blank you still have a current or a charge.. the measurement of the blank is done at least 3 times an with those 3 measures of current or charge you calculate standar deviation and 3 times that value in the calibration curve gives you the LOD.. and 10 times that value gives you the LOQ.. that just a method but the S/N=3 or S/N=10 is also good