Preconcentration of environmental waters by agar for XRF analysis

We have developed a convenient and effective XRF analysis procedure for trace amount of K, Ca, V, Mn, Fe, Ni, Cu, Zn, Cd, and Pb in environmental waters by using a preconcentration using the natural polymer (agar). The thin agar film was prepared by drying a homogeneous agar gel after mixing the aqueous sample solution with the agar powder. XRF analysis of the preconcentrated thin agar films containing trace metals showed a good repeatability because agar films were homogeneous enough. SB (signal to noise) ratios of the XRF intensity of the analytes were improved drastically. The linear calibration curves of K, Ca, V, Mn, Fe, Ni, Cu, Zn, Cd, and Pb showed a good linearity within the calibration ranges. The lower limits of detection (LLD) were 1.4 μ g/mL for K, 0.26 μ g/mL for Ca, 0.088 μ g/mL for V, 0.029 μ g/mL for Mn, 0.11 μ g/mL for Fe, 0.016 μ g/mL for Ni, 0.030 μ g/mL for Cu, 0.017 μ g/mL for Zn, 0.20 μ g/mL for Cd, and 0.066 μ g/mL for Pb, respectively. The proposed preconcentration method was applied to several environmental water samples.