Development of direct atmospheric sampling for laser ablation-inductively coupled plasma-mass spectrometry

Abstract

An atmospheric sampling approach for LA-ICP-MS is reported. Laser ablation sampling of various materials (gold, brass, and alloys) was carried out in ambient air without using a closed or any ablation cell. The laser generated aerosol containing air was directly sucked into a transport tube and transported towards the ICP-MS by a diaphragm pump. In front of the ICP, air was efficiently exchanged to argon by means of a gas exchange device recently developed for direct analysis of airborne particles by ICP-MS (Nishiguchi et al., J. Anal. At. Spectrom., 2008, 23, 1125). After exchanging air to argon, oxide formation, count rates of the gas blank and potential spectral interferences caused by polyatomic ions on most m/z ratios were found to be similar or lower in comparison to helium exchanged by argon, which indicates a complete exchange of air by argon. LA-ICP-MS analysis of various metallic samples under atmospheric conditions provided results with similar accuracy as commonly achieved with closed transport systems. The implementation of such a gas exchange device will open new applications, especially for objects difficult to place inside an ablation cell, such as archeological samples.