The performance of hypochlorous acid modified Ag nanoparticle-based assay in the determination of total antioxidant capacity of Boswellia Serrata and Aronia.

In this study, the SNPAC method was developed by using hypochlorous (ClO) at pH 9.3. Polyvinylpyrrolidone (PVP) was used as a stabilizer.

Ethylenediamine-bound magnetite nanoparticles as dual function colorimetric sensor having charge transfer and nanozyme activity for TNT and tetryl detection.

A reusable, low-cost, and convenient ethylenediamine (EDA)-bound magnetite nanoparticles (MNPs)-based colorimetric sensor has been developed for dual function colorimetric determination of nitroaromatic explosives such as TNT and tetryl. Colorimetric detection of analytes may occur through two independent routes: (1) nano-FeO- EDA- NH as σ-donor may interact with the σ- and π-acceptor aromatic-poly(NO) groups to produce a colored charge-transfer (CT) complex; (2) nano-FeO-EDA-NH as a Fenton-type nanozyme may generate reactive species that comprise hydroxyl radicals (OH) with HO to oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to a blue-colored diimine (oxTMB-TMB) CT complex, where this color is bleached with TNT/tetryl because of donor-acceptor interactions between the explosive -NO groups and the -NH group of FeO-EDA nanoparticles of restricted nanozyme activity. Both methods can quantify TNT well below the EPA recommended TNT residential screening level in soil, LOD being in the micromolar range.

Determination of total antioxidant capacity of Cynara Scolymus L. (globe artichoke) by using novel nanoparticle-based ferricyanide/Prussian blue assay.

A novel ferricyanide/Prussian blue (PB) assay for total antioxidant capacity (TAC) determination was developed exploiting the formation of PB nanoparticles in the presence of polyvinylpyrrolidone (PVP) as stabilizer. This improved method, named as "nanoparticle-based ferricyanide/Prussian blue assay (PBNP)", was applied to the TAC measurement of Cynara Scolymus L. (globe artichoke).

Determination of total antioxidant capacity of humic acids using CUPRAC, Folin-Ciocalteu, noble metal nanoparticle- and solid-liquid extraction-based methods.

Total antioxidant capacity (TAC) of humic acid (HA) samples was determined using CUPRAC (CUPric Reducing Antioxidant Capacity), FC (Folin-Ciocalteu), QUENCHER-CUPRAC, QUENCHER-FC, Ag-NP (Silver nanoparticle)‒ and Au-NP (Gold nanoparticle)‒based methods. Conventional FC and modified FC (MFC) methods were applied to solid samples. Because of decreased solubility of Folin-Ciocalteu's phenol reagent in organic solvents, solvent effect on TAC measurement was investigated using QUENCHER-CUPRAC assay by using ethanol:distilled water and dimethyl sulfoxide:distilled water with varying ratios.

Modeling of copper(II) and lead(II) adsorption on kaolinite-based clay minerals individually and in the presence of humic acid.

The aim of this study is to explain how clay minerals adsorb heavy metals individually and in the presence of humic acid, and to model heavy metal adsorption specifically based on surface-metal binary and surface-metal-ligand ternary complexation. The adsorption of Cu(II) and Pb(II) on kaolinite-based clay minerals has been modeled by the aid of the FITEQL3.2 computer program using single- and double-site binding models of the Langmuir approach.