Determination of trace and ultra-trace amounts of germanium in environmental samples by preconcentration in a graphite furnace using a flow injection hydride generation technique

Abstract

A method was developed for the trace and ultra-trace determination of germanium by flow injection (Fl) hydride generation with subsequent trapping and electrothermal atomization in a graphite furnace pre-coated with palladium. The samples were propelled into the Fl system to be merged on-line with a tetrahydroborate reductant. The hydride and hydrogen gases evolved were separated from the liquid phase in a gas–liquid separator and transferred to a palladium-coated graphite furnace pre-heated to 400 °C to collect the analyte, which was then atomized at 2500 °C. The sensitivities and interference effects using different concentrations of hydrochloric acid were compared. The tolerance to interferences was improved at high acidities of 3 mol l^–1 HCl and also in the Fl system when compared with a batch in situ collection system. With the reported system germanium was determined at a sampling frequency of 18 h^–1 with a detection limit (3σ) of 0.004 µg l^–1 in 0.15 mol l^–1 HCl medium and 0.03 µg l^–1 in 3 mol l^–1 HCl medium using a 4.5 ml sample. The precision (relative standard deviation) was 2.0% at the 0.3 µg l^–1 level in 0.15 mol l^–1 HCl medium and 2.5% at the 1.5 µg l^–1 level in 3 mol l^–1 HCl medium. The proposed method was applied to the determination of germanium in garlic, tap water, ginseng and geological reference samples.