In this article we discuss the calibration technique of standard addition.
Sometimes a peak of interest is somewhat obscured by noisy baseline or its response is attenuated (or magnified) by sample matrix, making accurate quantification difficult. These are common cases where the Standard Addition calibration technique might help. It is a bit more involved than the external calibration method previously described, but is similar to the internal standard methods discussed. As true for the other techniques of calibration, this can not compensate for interferences that completely co-elute with the target compounds of interest.
Let’s say that it looks like there might be a target peak (A) at the proper retention time as the target peak of interest, but it is near the detection limit where there is considerable noise (electronic and/or chemical), so it is difficult to tell. Let us say there is a second target peak (B) whose response is known to vary with sample matrix. In its case, response is higher than that of clean standards because the sample matrix suppresses liner activity, increasing analyte recovery when matrix is present (sometimes called matrix enhancement). Accurate quantification of these peaks would be a problem.
By reading the full article, you will learn more about the standard addition calibration technique and how, as with any calibration technique, the reliability of the quantification is only as good as the weakest step.
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