SAMPLE PRECONCENTRATION USING ION-EXCHANGE POLYMER FILM FOR LASER-ABLATION SAMPLING INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

An efficient sample pretreatment/introduction technique for the induct ively coupled plasma atomic emission spectrometry (ICP-AES) using ion exchange for analyte preconcentration and matrix separation and laser ablation sampling for sample introduction has been developed, Ammonium pyrrolidine dithiocarbamate (APDC)-polystyrene films are coated on gl ass plates for analyte preconcentration. Repetitive laser ablation sam pling of the polymer film removes the ion-exchanged metal ions from th e polymer film as fine particles for sample introduction into the ICP. After immersing the sample probe in a sample solution for 5 min, the ICP emission intensity for laser ablation of the polymer film is a few times larger than that after solution nebulization. The sample probe removes only a small fraction of the sample solution and, therefore, i n principle, does not disturb the original solution significantly. Sin gle-pulse laser ablation of the polymer film shows that the ion-exchan ged metal ion concentration in the film reduces exponentially with the depth of the polymer film. Ion exchange to the polymer film is probab ly limited by the rate of metal ion diffusion into the film. Calibrati on curves for Cu, Hg, Pb, and Zn show linear dynamic range of similar to 1-2 orders of magnitude. The linear dynamic range for Cu increases to >3 orders of magnitude when using Pb as an internal standard. RSD o f the ICP emission intensity is similar to 8%.