Reduction of dilution error in ELISAs using an internal standard

Area of Science:

• Biochemistry
• Analytical Chemistry
• Immunotechnology

Background:

• Dilution bias is a primary source of variability in immunoassays.
• Lack of an internal standard prevents accurate determination of true dilution values.

Purpose of the Study:

• To introduce and validate an internal control method for measuring dilution bias in immunoassays.
• To assess the impact of dilution bias correction on assay accuracy and precision.

Main Methods:

• An internal control (acridine-orange) was added at the initial dilution step of an ELISA.
• Fluorescent signals were monitored throughout serial dilutions to calculate a dilution factor.
• Assay results were corrected using the ratio of sample to reference fluorescent signals.

Main Results:

• The acridine-orange dilution correlated strongly with analyte-specific assay measurements (R² = 0.987).
• Correction using the measured dilution factor significantly improved assay accuracy and precision.
• A reduction of over 50% in the coefficient of variation (%CV) was achieved.

Conclusions:

• Dilution correction using an internal control substantially enhances the accuracy and precision of immunoassays.
• This strategy effectively mitigates dilution bias, a key contributor to immunoassay variability.
• Further control strategies can be explored to address other sources of assay variability.