Determination of silver in geological samples using high-resolution continuum source electrothermal atomic absorption spectrometry and direct solid sampling

This work describes the determination of silver in soil, sediment, rock and ore reference materials using direct solid sampling (SS) and high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). Pyrolysis and atomization temperatures were optimized as 800 A degrees C and 1,900 A degrees C, respectively, for soils and sediments, and calibration against aqueous standards resulted in good agreement between certified or informed and determined values at a 95% confidence level. The analysis of rocks and ores, however, required calibration against a solid certified reference rock sample, as in these materials the sulfur-rich matrix reduces the atomization efficiency. For these samples, background absorption with pronounced fine structure due to a sulfur-containing molecule has been detected, although with negligible influence on the analytical signal at the optimized atomization temperature of 2,300 A degrees C. The application of a least-squares background correction algorithm resulted in a background-free spectrum. A detection limit (3s, n = 10) of 2 ng g(-1) has been obtained. The proposed procedure has proved to be fast, sensitive and reliable for the analysis of geological samples using SS-HR-CS ET AAS.