Flow injection chemical vapor generation of Au using a mixed reductant

Sodium tetraethylborate was used to enhance the chemical vapor generation (CVG) efficiency of gold. Volatile species of Au in a weakly acidified buffer medium were generated at room temperature by reaction with a mixed reductant containing 0.1% NaBH₄ and 0.01% NaBEt₄ in the presence of 0.03% sodium diethyldithiocarbamate (DDTC). A flow injection (FI) system was coupled to a heated quartz tube atomizer for atomic absorption spectrometry (AAS) detection. A precision of 2.5% RSD (n=11, 0.4 mg/L level) was realized at sampling frequencies of 110/h. A detection limit of 2.8 ng/mL (3σ) was obtained based on a 500-μL sample volume. Compared with FI-CVG-AAS using NaBH₄ as the sole reductant, sensitivity was increased 8- to 10-fold. In situ trapping of the analyte in a graphite furnace followed by electrothermal AAS detection, as well as signal monitoring using ICP-OES, was used to study the system. Generation efficiency is estimated to be in the range of 0.8–6%.