High CVs at Bottom of Standard Curve

Symptom

Coefficient of variation (CV) among replicates is excessively high at the lowest standard concentrations (highest OD in competitive format), reducing precision at the sensitive end of the curve.

1. 1 Higher OD values inherently demonstrate greater variance in competitive format
2. 2 Pipetting errors more pronounced at small volume differences
3. 3 Standard concentrations approaching detection limit of the assay
4. 4 Samples falling outside optimal measurement range of curve

1. 1 Accept that higher ODs (lower concentrations) naturally show more variance in replicates
2. 2 Increase the concentration range of the standard curve to shift measurement window
3. 3 Dilute samples less so they fall in the middle of the standard curve
4. 4 Use technical triplicates or quadruplicates at low concentrations to improve precision

Related Video (2)

Thermo Fisher Scientific ★ 75

How to Run an ELISA Assay – Invitrogen Kit Step-by-Step Tutorial

"Step-by-step Invitrogen kit ELISA tutorial emphasizing accurate and reproducible detection, directly relevant to standard curve precision issues in competitive ELISA."

Bilibili (China-Accessible Mirrors) ★ 72

Thermo Fisher Microplate Reader Software Operation

"Microplate reader software operation video helps understand OD data acquisition and replicate averaging, where high CVs at the sensitive end of the curve are observed."