Scanometry as microplate reader for high throughput method based on DPPH dry reagent for antioxidant assay.

Area of Science:

• Analytical Chemistry
• Sensor Technology
• Spectrophotometry

Background:

• The 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical is a stable chromogenic compound used for antioxidant assays.
• Traditional antioxidant assays often require specialized equipment like UV/Vis spectrophotometers.
• Developing simple, cost-effective sensors for antioxidant capacity determination is of significant interest.

Purpose of the Study:

• To develop a simple antioxidant sensor using immobilized DPPH on microwell plates.
• To utilize a flatbed scanner as a microplate reader for antioxidant assays.
• To validate the sensor's performance for analyzing plant extracts.

Main Methods:

• Immobilization of stable chromogenic radical 1,1'-diphenyl-2-picrylhydrazyl (DPPH) solution on microwell plates as a dry reagent.
• Utilizing a flatbed scanner as a microplate reader for scanometry technique.
• Image analysis using ImageJ® program to obtain Red, Green, and Blue (RGB) values as sensor response.

Main Results:

• The developed sensor demonstrated a quantifiable antioxidant capacity range of 1-25 ppm as gallic acid equivalent (GAE).
• The sensor achieved a rapid response time of 9 minutes with good reproducibility (RSD < 1%) and recovery (93%-96%).
• The sensor successfully analyzed antioxidant capacity in plant extracts like sappan wood and turmeric rhizome, with results comparable to UV/Vis spectrophotometry.

Conclusions:

• A simple, cost-effective antioxidant sensor based on scanometry and immobilized DPPH has been successfully developed.
• The sensor provides reliable and reproducible results for determining antioxidant capacity in plant extracts.
• This method offers a viable alternative to conventional spectrophotometric techniques for antioxidant assays.