HYDRIDE GENERATION INTERFACE FOR THE DETERMINATION OF INORGANIC ARSENIC AND ORGANOARSENIC BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY USING OPEN-FOCUSED MICROWAVE DIGESTION TO ENHANCE THE PRE-REDUCTION PROCESS

An on-line interface was developed for ICP-MS based on hydride generat ion. The novelty of the approach resides in the use of an open-focused microwave digestion system to enhance the kinetics of a pre-reduction to elemental form, which is carried out using 2% v/v L-cysteine-0.2 m ol dm(-3) HNO3. This interface was characterized using flow injection to simulate transient HPLC peaks. It allows the total conversion of As -v, monomethylarsonic acid and arsenobetaine to As-III and then to a v olatile hydride within a few seconds. The conditions are also applicab le to the determination of Ge. Using only 20 mu I injections, improvem ents in sensitivity by a factor of 19 and 10 for As and Ge, respective ly, were achieved compared with those obtained by continuous nebulizat ion. The detection limit for both elements (independent of species) wa s also an order of magnitude lower than that achieved by continuous ne bulization, down to 0.06 and 0.08 ng cm(-3) for As and Ge, respectivel y.