Spectrofluorimetric determination of Zn²⁺ ions in aqueous medium using 5-(4-flourophenyl)-quinolin-8-ol

A spectrofluorimetric method based on complex formation between Zn²⁺ ions and 5-(4-flourophenyl)-quinolin-8-ol has been developed for the rapid determination of trace levels of zinc ions. The method is sensitive and selective. The complex formed emit strongly at 535 nm with excitation wavelength at 394 nm. Complexation formation was optimized by studying the effect of pH, molar ratio of the metal to the ligand and the type of buffers. The study indicated that maximum complexation resulted when the pH of the mixture was maintained at 8.0 with 0.2 M carbonate buffer and metal to ligand was at a stoichiometric ratio of 1:2. Under the optimum conditions, the detection limit was 3 ppb. Appropriate validation of the method, yielded acceptable relative standard deviations of less than 2% (n = 5). The method was applied to the trace determination of Zn²⁺ ions in tap water, mineral water, fresh milk and cream samples successfully.