In situ collection of volatile silver species in a new modular quartz tube atomizer for atomic absorption spectrometry

Abstract

Collection of volatile Ag species on a quartz surface has been successfully achieved for the first time, improving substantially the analytical performance of a previously reported on-line atomization procedure. Ag volatile species were formed during the reaction with tetrahydroborate in the presence of chemical modifiers (Triton X-100 and Antifoam B) in a special generator, collected and atomized in a quartz tube atomizer and detected by atomic absorption spectrometry. A novel modular design of the quartz tube atomizer was employed to allow trapping of volatile Ag species inside the optical tube heated to 1000 °C in excess of O₂ over H₂. Fast revolatilization and atomization of Ag species were subsequently realized by the change of the gas composition to H₂ excess over O₂. Collection efficiency under optimized conditions reached 94.1 ± 3.2%. The limit of detection was 0.11 ng ml⁻¹ for a 250 μl sample, nine times better than in the on-line atomization mode. Precision expressed as the relative standard deviation of measured trapping peak areas was 3% at the 4 ng ml⁻¹ level. The method was tested using water reference materials. The present shortcomings of this approach such as quartz devitrification at the collection area are discussed and feasible solutions are suggested.