Question

Please answer
Explain, in detail, how you calculate a limit of detection and why it is so important to report a limit of detection when presenting results for toxic heavy metals analysis in environmental samples?

Answer 1

The limit of detection or LOD is defined as the lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value) with a stated confidence level (generally, 99%). Therefore, the detection limit (DL) is a crucial factor in determining whether a substance (say, a toxic heavy metal in an environmental sample) can be identified and quantified with an acceptable level of confidence. There are a number of commonly used different DLs. One of them defines the LOD as the concentration corresponding to 3 times the RSD (relative standard deviation) for 10 reagent blank determinations.