New sorbents and indicator powders for preconcentration and determination of trace metals in liquid samples

Two approaches to immobilize complex-forming analytical reagents (PAN, PAR, Xylenol orange, Brombenzothiazo, Crystal violet, Cadion, and Sulfochlorophenolazorhodanine) for the preparation of new sorbents and indicator powders are suggested: on-line coating of reversed-phase silica gel by reagents or doping of porous sol-gel silica with reagents. The retention of Ag, Cd, Cu(II), Co(II), Fe(III), Mn(II), Ni, Pb, and Zn on the sorbents developed was investigated. Quantitative sorption and desorption conditions were optimized. Procedures for the determination of Cd, Cu(II), Fe(III), Pb, and Zn with flame atomic absorption, spectrophotometric, and diffusion scattering spectrometric detection were elaborated. Detection limits for Cd, Cu(II), Fe(III), Pb, and Zn were 3 μg/L, 6 μg/L, 5 μg/L, 40 μg/L, and 1 μg/L, respectively. The procedures were used for the analysis of various real samples, e.g., natural and waste waters, and food. Received: 17 July 1997 / Revised: 20 January 1998 / Accepted: 5 February 1998