Absent Standard Curve Signal with Normal Zero Standard

Symptom

No detectable signal is observed for standard curve points containing analyte, while the zero standard (maximum binding control) shows normal OD values, indicating complete loss of competitive inhibition.

1. 1 Pipetting errors or dilution mistakes during standard preparation
2. 2 Standard concentration far exceeds assay dynamic range causing complete competition
3. 3 Standard stock solution degradation or improper reconstitution
4. 4 Cross-contamination of standard wells with high-concentration standard

1. 1 Verify proper pipetting technique and serial dilution accuracy for standard curve
2. 2 Decrease the starting concentration of standard to bring it within assay dynamic range
3. 3 Prepare fresh standard solution and verify proper reconstitution per kit instructions
4. 4 Use dedicated pipette tips for each standard dilution to prevent cross-contamination

Related Video (2)

Thermo Fisher Scientific ★ 78

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

"Step-by-step Invitrogen kit tutorial demonstrates correct standard/sample dilution and pipetting steps directly implicated in this failure."

Bilibili (China-Accessible Mirrors) ★ 72

R&D Systems Quantikine ELISA Operation Guide

"Official Quantikine protocol covers standard preparation and curve setup, useful for spotting dilution errors that cause lost competitive inhibition."