A COMPARISON OF ACID DISSOLUTION PROCEDURES FOR THE DETERMINATION OF HG AND AS IN SEDIMENTS BY COLD VAPOR - HYDRIDE GENERATION AAS

Five acid treatments were compared for the determination of mercury an d arsenic in Certified Reference Sediments via cold vapour (Hg) and hy dride generation (As) A.A.S. After optimisation of instrumental parame ters (details are given), matrix effect was investigated for all the d issolution procedures adopted, comparing results obtained with the sta ndard addition method and with the calibration curve method by means o f a non-parametric statistic test (Kruskal-Wallis). The same test was used for the comparison of the dissolution procedures. It was found th at, among the procedures investigated, only the HNO3-HF mixture in clo sed, microwave heated teflon vessels lead to results that are in the c ertified concentration range both for As and for Hg.