Amitav Sen

The Limit of Detection (LOD) from a Differential Pulse Voltammetry (DPV) plot can be determined by following these steps:

First prepare calibration curve by measuring DPV responses with varying the concentration of analyte, plot the peak current vs. concentration, identify the linear region, do the linear fitting and calculate the slope.

The slope of the calibration curve in the linear range represents the sensitivity (usually in units like µA/µM).

Then determine the standard deviation of the blank by performing DPV measurement with a blank solution (usually at least 10-20 measurements).Compute the standard deviation of the peak current values obtained from these blank measurements.

Use the following formula to calculate the LOD:

3*S.D./Slope

Example:

- Suppose the standard deviation of the blank is 0.5 µA, and the slope of the calibration curve is 10 µA/µM.

- The LOD would be: 0.15 µM

This value represents the lowest concentration of the analyte that can be reliably detected by the DPV method under the given conditions.

- Ensure that the calibration curve is linear and that the blank measurements are accurate and repeatable.

- The factor "3" in the LOD formula is based on a commonly accepted convention for signal-to-noise ratio (S/N) of 3, indicating the point where the analyte signal can be reliably distinguished from the noise.

The supporting file of the given ACS article is really helpful for these calculations.

https://pubs.acs.org/doi/10.1021/acsomega.1c05989?goto=supporting-info

Hello,

In the procedure for the LOD determination described by Jagriti Gupta, the blank signal standard deviation can reasonably be replaced by the residual standard deviation of the regression line, since the linear fit has already been done and then, the residual standard deviation is given by the software. Note that it should be about the dependence of the analytical signal (the peak height in this case) on concentration near zero, not about the "calibration curve" in a common sense, since the slope in this specific range may be different from that of the entire calibration function.

Concerning the standard deviation derived from the blank measurements, the recommendation to perform "at least 10-20 measurements" (in addition to those needed to previously estimate the slope) seems quite unreasonable. The standard deviation depends on experimental conditions and increasing the number of replicates under the same conditions does little to increase the reliability of the LOD estimate (that is generally indicative in nature).

Rouvim Kadis I am totally agreeing with you . Amitav Sen

Please refer for more detail https://doi.org/10.1021/acsomega.9b03125

Jagriti Gupta Does it specifically have to be the SD of blank (repeated blank measurements, then finding the SD of these measurements) or it is the SD of the blank and varying concentrations of the analyte (say 0 to 10mM, for example and 0 is the measurement of the blank). If there's a standard literature reference for this, you could also share.