A terminating reagent for the peroxidase-labelled enzyme immunoassay

Area of Science:

• Biochemistry
• Immunology
• Analytical Chemistry

Background:

• Enzyme immunoassays (EIAs) are widely used for detecting specific analytes.
• Peroxidase-based EIAs often employ substrates like 2,2′-azino-di(3-ethylbenzthiazoline sulphonic acid-6) (ABTS) for colorimetric detection.
• Sodium azide is sometimes used as a preservative in biological reagents.

Purpose of the Study:

• To investigate the effect of sodium azide concentration on color development in peroxidase-labelled EIAs.
• To determine if low concentrations of sodium azide can inhibit color development without affecting substrate integrity.

Main Methods:

• A peroxidase-labelled enzyme immunoassay was performed using 2,2′-azino-di(3-ethylbenzthiazoline sulphonic acid-6) as the substrate.
• Varying concentrations of sodium azide were added to the reaction mixture.
• Color development was measured spectrophotometrically.

Main Results:

• Addition of low concentrations of sodium azide completely inhibited color development.
• High concentrations of sodium azide led to a decrease in color intensity.
• Low concentrations of sodium azide did not significantly affect the final color intensity, but prevented its development.

Conclusions:

• Low concentrations of sodium azide are effective inhibitors of color development in peroxidase-based EIAs with ABTS substrate.
• This inhibitory effect can be utilized to prevent unwanted color formation and potential false positives in immunoassay procedures.
• Careful control of sodium azide concentration is necessary to avoid compromising assay sensitivity.