Agnieszka Tułodziecka

Development of a novel gold nanoparticle-based method to determine antioxidant capacity of Brassica oilseeds, white flakes and meal

Antioxidant capacity (AC) of Brassica oilseeds, white flakes and meal was determined by a new spectrophotometric method. The proposed assay (AuNP) based on the formation of gold nanoparticles (AuNPs) in an acetic buffer medium (pH=4.6) was compared with the previously described silver nanoparticle-based (AgNP), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin-Ciocalteu (FC) procedures. The novel AuNP method was validated using standard antioxidants such as phenolic acids and quercetin. The AC of rapeseed, white flakes and meal varied from 10.0 to 86.7μmolsinapicacid(SA)/g, 26.5-160.3μmolSA/g, 6.8-103.0μmolSA/g, 23.0-259.3μmolSA/g and 6.9-92.1μmolSA/g for AuNP, AgNP, FRAP, DPPH and FC methods, respectively. The proposed AuNP method is simple, precise (intra-day RSD=0.27-2.11% and inter-day RSD=2.05-4.87%) and accurate (recovery=96.2-104.3%) and can be useful in the routine analysis of the AC.

A novel iron oxide nanoparticle-based method for the determination of the antioxidant capacity of rapeseed oils at various stages of the refining process

A novel iron oxide nanoparticle-based (IONP) method and two modified methods: ferric reducing antioxidant power (FRAP) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) were used for the determination of the antioxidant capacities of the acetonic, ethanolic and methanolic extracts of rapeseed oils from different stages of technological processes. The IONP method based on the reduction of ferric ions by oil antioxidants in acidic medium and the formation of yellow solutions of iron oxide nanoparticles (IONPs) has been elaborated. The novel IONP method was validated using sinapic acid (SA), caffeic acid (CA), gallic acid (GA), ferulic acid (FA), vanillic acid (VA) and Trolox (TE) as standard antioxidant solutions. The average antioxidant capacities of the studied rapeseed oils ranged between 2594 and 4946 μmol SA/100 g for the proposed IONP method, 58–315 μmol SA/100 g for the FRAP method, and 462–1511 μmol SA/100 g for the DPPH assay. Satisfactory values of precision (RSD = 0.5–3.4%) demonstrate the benefit of the proposed IONP method for analysis of the antioxidant capacity of rapeseed oil samples.