HPLC LOD / LOQ experiment using signal-to-noise ratio

Using the S/N method to determine LOD and LOQ for an HPLC analysis, would the experiment look something like this?

  • Prepare standard solutions at varying, yet very low concentration.
  • Inject them as per the method.
  • Calculate S/N for each.
  • Finally, determine which concentration of solution exhibits a S/N ~ 3:1 and this becomes the detection limit (LOD). Likewise the solution with S/N ~ 10:1 becomes the limit of quantitation (LOQ).

I would also apply a requirement of RSD NMT 20% for all injections at the LOQ.

Do you agree with this basic LOD/LOQ experiment?
Any advice would be helpful as I am reviewing a contractor’s work which doesn’t seem to make sense to me.


That seems reasonable to me. If there is placebo product matrix available, I might spike that with those concentrations instead of just using dilute standard solution.