How do I calculate ELISA sample concentrations from a standard curve?

Subtract the blank from every optical density, fit a 4PL or 5PL model to the standard series, then interpolate each sample OD on the inverse of the fitted curve. Labreador does this in the browser and flags values outside the LLOQ/ULOQ range as extrapolated.

What is the difference between IC50 and EC50?

EC50 is the concentration producing 50% of the maximal response for a stimulatory curve; IC50 is the concentration causing 50% inhibition. Both come from the same 4PL/5PL fit — only the direction of the response differs.

How is relative potency determined in a parallel line analysis?

Fit reference and test curves with shared slope and asymptotes, verify parallelism with an F-test, then take the horizontal shift between the curves on the log-dose axis. Relative potency (%) is 10^(log EC50 reference − log EC50 test) × 100.

How do I know if my ELISA assay is valid?

Check the R² quality tier (Tier 1 ≥0.98; Tier 2 ≥0.95), residual pattern, back-calculated standard recovery (85–115% for ordinary standards, 80–120% at LLOQ/ULOQ), replicate CV%, and Method Health. Method Health diagnoses OD span, signal-to-blank ratio, EC50 placement, EC50 CI spread and R²; recovery and replicate CV are reported separately.

Which ecotoxicology indices can be computed for trace elements?

Estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), contamination factor (CF), pollution load index (PLI), geoaccumulation index (Igeo), bioaccumulation factors (BAF/BSAF) and biometric indices such as Fulton condition factor.

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