CHELATION PRECONCENTRATION WITH RESIN ANALYSIS BY DIRECT SAMPLE INSERTION INDUCTIVELY-COUPLED PLASMA SPECTROMETRY

Batch preconcentration with Chelex-100 followed by direct analysis of the analyte-laden resin by direct sample insertion inductively coupled plasma atomic emission spectrometry (DSI-ICP-AES) is described. The p erformance of the technique is element specific. Quantitative retentio n of Cu, Zn, Cd and Pb on the resin is achieved, but only for Cu and Z n does the ratio of the signal before and after preconcentration appro ach the theoretical preconcentration factor. This observation is mainl y caused by the adverse effect of the remnants of the resin after ashi ng on the excitation properties of the plasma. This is clearly shown b y monitoring the ratio of the intensity of a Pb ionic line to a Pb ato mic emission line. If the ashing temperature is increased, Cd and Pb a re prematurely vaporized in the ashing stage, which is performed with inductive heating in the graphite DSI probe. Increasing the radiofrequ ency power sustaining the ICP improves the performance of the techniqu e.