On-line Determination of Zinc in Water and Biological Samples after Its Preconcentration onto Zincon Anchored Polyurethane Foam

Abstract

A fast and sensitive on-line procedure for the determination of zinc in water and biological samples was developed. Zinc was preconcentrated in a mini-column packed with polyurethane foam (PUF) chemically modified with zincon via –N=N– bonding. The optimal conditions for preconcentration were pH 8.5 and sample flow rate of 4.0 mL min⁻¹. Quantitative desorption of Zn(II) was obtained by 0.1 mol L⁻¹ hydrochloric acid and subsequent spectrophotmetric determination using 4-(2-pyridylazo)-resorcinol at 498 nm. The obtained detection limit was found to be 3.0 ng mL⁻¹, precision (RSD) was 4.8 and 6.7% at 20 and 110 ng mL⁻¹, respectively, for 60 s preconcentration time and enrichment factor was 31. The linearity range was from 10 to 120 ng mL⁻¹ and maximum sample throughput was 20 h⁻¹. Finally, the method was successfully applied to the determination of zinc in tap water, Nile River water and human urine samples with RSD in the range of 1.1 – 8.3%.