A highly selective and sensitive pyridylazo-2-naphthol-poly(acrylic acid) functionalized electrospun nanofiber fluorescence “turn-off” chemosensory system for Ni2+

Abstract

A fluorescent nanofiber probe for the determination of Ni²⁺ was developed via the electrospinning of a covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymer. Fluorescent nanofibers with diameters in the range 230–800 nm were produced with uniformly dispersed fluorophores. The excitation and emission fluorescence were at wavelengths 479 and 557 nm respectively, thereby exhibiting a good Stokes' shift. This Ni²⁺ probe that employs fluorescence quenching in a solid receptor–fluorophore system exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 μg mL⁻¹ based on the Stern–Volmer mechanism. The probe achieved a detection limit (3δ/S) of 0.07 ng mL⁻¹ and a precision, calculated as a relative standard deviation (RSD) of <4% (n = 8). The concentration of Ni²⁺ in a certified reference material (SEP-3) was found to be 0.8986 μg mL⁻¹, which is significantly comparable with the certified value of 0.8980 μg mL⁻¹. The accuracy of the determinations, expressed as a relative error between the certified and the observed values of certified reference groundwater was ≤0.1%. The versatility of the nanofiber probe was demonstrated by affording simple, rapid and selective detection of Ni²⁺ in the presence of other competing metal ions by direct analysis, without employing any further sample handling steps.