Polyethersulfone membrane printed with 1-(2-pyridylazo)-2-naphthol (PAN) sensor for sensitive enrichment and rapid determination of Zn2+ in water

Abstract

A facile approach for the rapid and sensitive detection as well as determination of Zn²⁺ ions in water has been developed. The method was based upon the use of a polyethersulfone membrane printed with 1-(2-pyridylazo)-2-naphthol (PAN) as a novel platform for rapid enrichment of Zn²⁺ ions. Atomic force microscopy, scanning electron microscopy and goniometer studies were performed to understand the PES characteristics. The end result for Zn²⁺ determination was visually noticeable via a distinct colour change on the membrane surface from 10⁻³ μg mL⁻¹ onwards, with a linear dynamic range of 10⁻¹ to 10² μg mL⁻¹. The specificity of the proposed sensor was improved by masking common interfering ions towards Zn²⁺ in water. The developed platform is robust enough to withstand slight changes in pH, temperature and volume, confirming its applicability in point-of-use testing. The proposed membrane-based sensor provides better performance compared to the similar assay executed on a pristine filter-paper platform with a maximum limit of detection of only up to 10¹ μg mL⁻¹. The developed sensor was satisfactorily applied for the analysis of Zn²⁺ ions in tap- and wastewater samples without pretreatment with an acceptable relative standard deviation (RSD) ≤ ±2.9%. The precision of the proposed method was also estimated for inter- and intra-day replicates (n = 5) at various concentrations and RSD values of less than 11.0% were achieved. Statistical treatment using t- and F-tests of the results of the developed sensor with those obtained by the standard method reflected no significant differences in the precision.