GASEOUS SAMPLE INTRODUCTION FOR THE DETERMINATION OF SILICON BY ICP-AES

The generation of volatile species of silicon as a means to introduce silicon into an inductively coupled plasma has been studied. It is bas ed on the reaction between silicon and fluoride ions in sulfuric acid media and it was carried out using different flow injection mountings. The first mounting works with an injection of 100 mu L concentrated s ulfuric acid and 150 mu L silicon standard solution in a continuous 0. 05 mol L-1 NaF solution flow. The method shows a linear response betwe en the intensity of emission at 251.611 nm line and the silicon concen tration from 0.1 to 200 mu g mL(-1), with a reproducibility of 2% and a detection limit of 0.004 mu g mL(-1). The second mounting produces t he volatile species by the reaction between two opposed aerosol flows in a home-made nebulization chamber. This chamber has a Cross-Flow and a Meinhard nebulizer at either end. A linear response ranging from 0. 1 to 1000 mu g mL(-1) of silicon solution is obtained and the reproduc ibility rises to 8%. The detection limit reached is 0.02 mu g mL(-1). The silicon content in real water samples was determined by applying b oth the above-mentioned methods and a third method for reference.