# Deposition Efficacy of Natural and Synthetic Antioxidants on Fabrics
## Materials and Methods
### Antioxidant Activity Test  
Antioxidants in aqueous solution: Antioxidant activity in solution was measured using the ABTS radical cation (ABTS\({}^{\bullet+}\)) decolourisation assay with some modifications [33; 34]. Radical scavenging capability of the tannin in aqueous solution was determined by measuring the decrease in absorbance of ABTS\({}^{\bullet+}\) at \(\lambda\) = 730 nm after a fixed incubation time of the radical cation solution with the sample to be tested using a spectrophotometer with a thermostatic cell container equilibrated at 30 \({}^{\circ}\)C. ABTS\({}^{\bullet+}\) was produced by reacting ABTS (7.00 mm final concentration) with sodium persulfate (2.45 mm final concentration); the mixture was allowed to stand in the dark at room temperature for 12-16 h before use (oxidation of the ABTS starts immediately, but the absorbance was not found stable before 6 h of reaction time). The radical is stable in this form for two days when stored in the dark at room temperature. Aqueous ABTS\({}^{\bullet+}\) solution (7.00 mm) was diluted with distilled water to an absorbance in the range of 0.65-0.70 and equilibrated at 30 \({}^{\circ}\)C. After addition of 1000 \(\mu\)L of this diluted ABTS\({}^{\bullet+}\) solution to 10 \(\mu\)L of aqueous tannin solution (1 mg/mL) or alternatively 10 \(\mu\)L of a phenolic antioxidant compound (final concentration range 0-25 mm), the absorbance reading was taken exactly at 30 \({}^{\circ}\)C, 1 min after initial mixing. An appropriate blank was run in the assay. The percentage inhibition of absorbance at \(\lambda\) = 730 nm was calculated and plotted as a function of concentration of antioxidant related to the standard reference data, i.e., mg of ascorbic acid equivalent (AAE) per mg of dry antioxidant substance.  
Actives deposited on fabric: Antioxidant activity of actives deposited on fabric was measured using an adopted ABTS\({}^{\bullet+}\) decolourisation assay. After addition of 1.0 mL of diluted ABTS\({}^{\bullet+}\) solution (\(A_{730\text{nm}}\approx 0.7\); see above) to 10 mg treated fabric sample, or, alternatively, 10 \(\mu\)L of phenolic antioxidant compounds or antioxidant standard (final concentration range 0-25 \(\mu\)m) the absorbance reading was taken exactly 1 min after initial mixing at 30 \({}^{\circ}\)C after an ultimate shake of the solution approximately 5 s before measurement, to allow the paper to sink to the bottom prior to the measurement. A blank was run in the assay using a nontreated fabric sample. The percentage inhibition of absorbance at \(\lambda\) = 730 nm was calculated and plotted as a function of concentration of actives related to the standard reference data, i.e., as \(\upmu\)g of ascorbic acid equivalent (AAE) per 10 mg fabric portion.  
Amount of antioxidant industrially deposited on fabric: The amount of deposited antioxidant was determined by measuring the absorbance decrease, after a fixed incubation time, of ABTS**+** solution (\(A_{730\text{nm}}\approx 0.7\); see above) with treated fabric samples (weighing 10.0 mg each), based on a specific calibration curve (final concentration range 0-2.5 \(\upmu\)g/mL) obtained with the same approach and using an aqueous antioxidant solution accounting for the antioxidant type used.