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.

Abstract

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 H2O2 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 H2O2, 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 Au0 and suppressing oxidation of p-dimethylaminobenzaldehyde ehrlich's bio-reagent. In this system which contains PVA-GNPs, H2O2, 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 × 10-6 M, 6.64 × 10-8 M and 9.93 × 10-9 M and linear ranges between 1.98 × 10-5-1.22 × 10-3 M, 1.99 × 10-6-2.0 × 10-4 M and 1.07 × 10-7- 2.86 × 10-5 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.