Analytical characteristics of an inductively coupled plasma mass spectrometer coupled with a thermospray nebulization system

Abstract

The analytical characteristics of a thermospray sample introduction system coupled to an inductively coupled plasma mass spectrometer have been evaluated. The results obtained with the thermospray system were compared with those obtained with two other arrangements, namely the pneumatic nebulizer coupled with a spray chamber (the conventional arrangement) and the same pneumatic nebulizer coupled with the desolvating unit employed with the thermospray nebulizer. In the presence of salts of Na (NaNO₃) or Ca [Ca(NO₃)₂], the non-spectroscopic interferences (analyte ion signal suppression) were more pronounced in the thermospray system than in the conventional arrangement, whereas in the presence of mineral acids (H₂SO₄, H₃PO₄) both systems gave similar suppressions. The apparent analyte element concentrations due to spectral overlap with MO_x⁺(e.g., SO⁺, SO₂⁺, PO⁺, PO₂⁺, CaO⁺) or ArM⁺(e.g., ArNa⁺, ArS⁺, ArP⁺) were lower or similar for the thermospray nebulizer in comparison with those obtained with the conventional arrangement. In order to reduce memory effects, a sample flow injection system was used for the analysis of three candidate environmental reference materials [Community Bureau of Reference (BCR) Certified Reference Materials 141R Soil-calcareous loam, 144R Sewage sludge—domestic and 146R Sewage sludge—industrial]. The accuracy and precision of external calibration with internal standardization, standard additions and isotope dilution were compared. Similar results were obtained for the aqua regia soluble content of Cd and Pb in these materials.