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Measure the antioxidant efficacy of your ingredients, your products
with an ORAC test

The ORAC test allows to determine the antioxidant power of an ingredient, a compound, a formula, based on their capacity to trap free radicals.

Standardized test

Quantitative measurement

Description of the test

The ORAC method aims to evaluate the ability of a sample to limit the oxidation of a fluorescent reagent such as fluorescein which is a probe sensitive to oxidation. The oxidation of fluorescein is accompanied by a decrease in fluorescence measured over time at an excitation wavelength of 485nm and an emission wavelength of 520nm. This change in fluorescence is directly related to the number of free radicals. Indeed, the presence of antioxidants leads to an inhibition of free radicals that damage the fluorescent compound. The standard antioxidant used is TROLOX, a water-soluble vitamin E analog. Fluorescence decay kinetics are assessed every minute for one hour.

to provide

  • Sample to analyze :
    – For liquids : 1-5 ml
    – For solids : 5-10 mg
  • Following information for each sample :
    – Chemical nature: all chemical natures except radioactive elements.
    – Form : solid (granular, powdery, etc …) liquid.
    – Solubility : soluble or insoluble in the experimental conditions (culture medium).
    – Concentration
    – Shipping conditions: depending on the type of molecule and the packaging recommended to maintain its stability.


The higher the ORAC index, the more antioxidant properties the test sample possesses in a quantitative way. This index or relative value of ORAC is defined as a ratio between the difference between the areas under the curves of the test sample and the blank, and the difference between the areas under the curves of the Trolox and the blank. The results are therefore expressed as molarity of Trolox per molarity or mass of sample tested.


A standard range of Trolox is performed at different concentrations (0-100µM).

Each sample to be tested is made in triplicate and the plate containing all the samples and the standard range is incubated for 30 min at 37°C.

Once incubation is complete, fluorescence kinetics (ex.485nm em.520) are recorded every minute for 1 hour.

The ORAC test applies
to several areas

biology services


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