Colorimetric determination of F, Br and I ions by Ehrlich's bio-reagent oxidation over enzyme mimic like gold nanoparticles: Peroxidase-like activity and multivariate optimization.

Citrate and polyvinyl alcohol capped gold nanoparticles (PVA-GNPs) were synthesized via chemical reduction technique and fully characterized by DLS, SEM, EDS, XRD, UV-Vis and FT-IR analysis. A simple and practical colorimetric sensor based on red-ox reaction of p-dimethylaminobenzaldehyde (DABA) as ehrlich's bio-reagent and Au(III) with HO on PVA-GNPs mimic catalyst with enzyme-like activity, has been fabricated for determination of F, Br and I halide anions. Prepared PVA-GNPs, can simultaneously catalyze the disintegration of HO, that used to reduce Au(III) ions into co-doped Au-NPs and oxidation of p-dimethylaminobenzaldehyde ehrlich's bio-reagent while in the presence of halide ions Au-X complex can be formed and improved sensor selectivity. Halide ions (F, Br and I) effectively diminishes the catalytic activity of GNPs to disintegrate oxygenated water by the interaction among Au and Au and suppressing oxidation of p-dimethylaminobenzaldehyde ehrlich's bio-reagent. In this system which contains PVA-GNPs, HO, p-dimethylaminobenzaldehyde ehrlich's bio-reagent, and Au(III), increasing the halide ions (F, Br and I) concentration show color changes from deep green to red. In view of this rule, in this work, a novel colorimetric technique for sensitive determination of F, Br and I was developed. This method has the detection limits of 2.60 × 10 M, 6.64 × 10 M and 9.93 × 10 M and linear ranges between 1.98 × 10-1.22 × 10 M, 1.99 × 10-2.0 × 10 M and 1.07 × 10- 2.86 × 10 M for F, Br and I, respectively. Assays are highly selective over other ions. They effectively applied to detection of halide ions in real water samples.