Analytical Sciences

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

Sami M. Abdel AZEEM,*1,*2 Hassan A. HANAFI,*2,*3 and M. F. EL-SHAHAT*4

*1 Chemistry Department, Faculty of Science, Fayoum University, Fayoum City, Egypt
*2 Collage of Science and Humanities-Al-Quwaiyah, Shaqra University-KSA, Saudi Arabia
*3 Cyclotron Project, Nuclear Research Center, Atomic Energy Authority. P. N., 13759, Cairo, Egypt
*4 Chemistry Department, Faculty of Science, Ain-Shams University, Cairo, Egypt

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%.

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