Hydride Generation Laser-Induced Fluorescence of Arsenic and Selenium in the Inductively Coupled Plasma and Electrothermal Atomizer

The application of hydride generation (HG) sample introduction combined with laser-induced fluorescence (LIF) detection in the inductively coupled plasma (ICP) and electrothermal atomizer (ETA) is reported. Far-ultraviolet excitation of As at 193.696 nm and Se at 196.026 nm is accomplished by using a tunable dye laser system with frequency doubling and stimulated Raman scattering. HG-ICP-LIF and HG-ETA-LIF techniques have been developed and demonstrate good sensitivity and good linearity at the ng/mL to sub-ng/mL level for both elements. The relative standard deviation of replicate measurements is on the order of 3–10% at the 5 ng/mL level for the HG-ICP-LIF technique and 5–35% at the 0.6 ng/mL level for the HG-ETA-LIF technique. Detection limits of 1 ng/mL (5 ng absolute mass) for As and 0.06 ng/mL (0.3 ng) for Se are reported for the HG-ICP-LIF technique and 0.04 ng/mL (0.2 ng) for As and 0.16 ng/mL (0.8 ng) for Se are reported for the HG-ETA-LIF technique. Lower than expected sensitivity and precision are observed in the ETA, which may be due to inefficient trapping of the hydrides in the procedure. Selective HG procedures have been demonstrated for the speciation and recovery of selected oxidation states of As and Se. The analytical capabilities of the HG-LIF techniques are compared to those of other HG techniques, and recommendations are made for improved performance of future HG-LIF approaches.