Yannick Joseph Francois Lerat

Silver matrix effects on gold atomization in a graphite furnace investigated by two-dimensional laser imaging with a gated charge coupled device camera

A pulsed intensified charge coupled device (CCD) camera was used to make a diagnostic of perturbations, generated by increasing silver quantities, on the fluorescence signal of small amounts of gold. Using both absorption and laser-induced fluorescence (LIF) spectroscopy, pictures of the furnace, probed with a pulsed laser tuned on a gold transition, were recorded during the atomization step. Spectra of the atomic and molecular fluorescence generated by the laser were recorded using classical electrothermal atomization LIF. These data enabled the mapping of the atomic and molecular species distribution in the furnace, and the identification of the chemical nature of these molecules. No pronounced changes were observed in the gold atoms distribution when about 100–200 µg of silver were atomized, relative to atomization of gold in a pure water matrix. For the silver matrix (≈1 mg), important silver condensations were formed and the distribution of gold atoms were strongly modified.

Characterization and reduction of silver matrix induced effects in the determination of gold, iridium, palladium, platinum and rhodium by graphite furnace laser-induced fluorescence spectrometry

The determination of ultratraces of Au, Ir, Pd, Pt and Rh in silver nitrate by graphite furnace laser-induced fluorescence (GF–LIF) spectrometry is subject to strong interference by the formation of condensation. Two kinds of condensation are clearly identifiable: diatomic molecules (AgH, Ag2) and condensed particles. In order to find the best analytical parameters for the determination of Au, Ir, Pd, Pt and Rh in silver nitrate by GF–LIF, a detailed study of the origin and spatio-temporal behaviour of these condensations was carried out. Solutions for matrix interference reduction are proposed, these include the use of neon as a purge gas, a preliminary evaporation of part of the matrix prior to atomization, and the use of a transverse heated atomizer.

Electrothermal atomization-laser induced fluorescence determination of iridium, rhodium, palladium, platinum and gold at the ng/l level in pure water

Abstract Trace determination of Au, Rh, Ir, Pd and Pt in pure water solution has been performed by electrothermal atomization-laser induced fluorescence (ETA-LIF). Limits of detection obtained are in the ng/l −1 range, improving previously published absolute limits of detection by one or two orders of magnitude. The day to day reproducibility for iridium is around 8%. Thus, the ETA-LIF technique can be used routinely for the determination of precious metals at ultratrace concentrations.

Imaging of analyte distribution in a graphite tube atomizer by laser induced fluorescence

The combination of a tunable laser with an intensified charge-coupled device camera provides a powerful two dimensional imaging system to investigate the distribution of species during atomization in a graphite furnace. It can be set up to measure attenuation of the incident laser beam, together with the fluorescence of the species. The example of gold atomization in a silver matrix is described to show the advantage of the system in understanding the formation and expansion of the vapour in two different types of graphite furnaces. The two furnace systems are an end heated atomizer and a transversely heated atomizer. The strongest perturbations in gold atom distribution in the presence of the matrix come from metallic silver condensation. These condensates are formed regardless of the heating mode when atomizations are performed directly from the wall. Condensation is not observed when a platform is used in the transversely heated atomizer.