hosphomolybdate-based assays are commonly used to measure the antioxidant activity of a sample. One of the most popular assays is the phosphomolybdate method, which involves the reduction of Mo(VI) to Mo(V) and the formation of a green phosphate–molybdenum complex, which can be quantified spectrophotometrically.

General Phosphomolybdate Assay Procedure:

Formula for Antioxidant Activity Calculation:

The percentage inhibition of the molybdate complex formation can be calculated using the following formula:

Inhibition Percentage=(1−Absorbance of SampleAbsorbance of Control)×100\text{Inhibition Percentage} = \left( 1 - \frac{\text{Absorbance of Sample}}{\text{Absorbance of Control}} \right) \times 100Inhibition Percentage=(1−Absorbance of ControlAbsorbance of Sample​)×100

Where:

• Absorbance of Sample is the absorbance of the sample at 695 nm after the reaction.
• Absorbance of Control is the absorbance of the blank or the control without the antioxidant.

Alternatively, if you are calculating Trolox equivalent antioxidant capacity (TEAC), use:

TEAC=Absorbance of SampleAbsorbance of Trolox Standard×Trolox Concentration\text{TEAC} = \frac{\text{Absorbance of Sample}}{\text{Absorbance of Trolox Standard}} \times \text{Trolox Concentration}TEAC=Absorbance of Trolox StandardAbsorbance of Sample​×Trolox Concentration

This gives the antioxidant activity in terms of the equivalent amount of Trolox (a water-soluble vitamin E analogue), making it easier to compare across different studies.