High-Throughput Assay of Oxygen Radical Absorbance Capacity (ORAC) Using a Multichannel Liquid Handling System Coupled with a Microplate Fluorescence Reader in 96-Well Format

TLDR

The ORAC assay, a standard tool for measuring antioxidant activity, is limited by discontinued analyzers and labor‑intensive manual preparation. This study aimed to create a fully automated, high‑throughput platform for the ORAC assay. The platform combines an eight‑channel robotic liquid handler with a microplate fluorescence reader. Using the platform increased throughput by at least tenfold, with intra‑ and interday CVs below 15 % and LOD/LOQ of 5 µM and 6.25 µM, respectively.

Abstract

The oxygen radical absorbance capacity (ORAC) assay has been widely accepted as a standard tool to measure the antioxidant activity in the nutraceutical, pharmaceutical, and food industries. However, the ORAC assay has been criticized for a lack of accessibility due to the unavailability of the COBAS FARA II analyzer, an instrument discontinued by the manufacturer. In addition, the manual sample preparation is time-consuming and labor-intensive. The objective of this study was to develop a high-throughput instrument platform that can fully automate the ORAC assay procedure. The new instrument platform consists of a robotic eight-channel liquid handling system and a microplate fluorescence reader. By using the high-throughput platform, the efficiency of the assay is improved with at least a 10-fold increase in sample throughput over the current procedure. The mean of intra- and interday CVs was <or=15%, and the limit of detection and limit of quantitation were 5 and 6.25 microM, respectively.