Combination of multielement technique (INAA and ICP-MS) for a French air pollution bio-monitoring survey using mosses

This work presents the use of two trace analysis techniques through the data obtained for a significant part of the 557 mosses sampled in France. Sampling were made within the framework of European survey carried out in 1995-1996 and proposed by the Nordic Council. The analyses were produced with a combination of two multielement analysis techniques: INAA (Instrumental Neutron Activation Analysis) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry). Theses two techniques were suitable for trace analyses in mosses. They were clearly complementary and provided for 36 elements including the heavy metals of key interest in air pollution studies. The choice of the technique for a given element depended on the feasibility (e g. Pb is not attainable by INAA), the detection limit, the analytical variability, the preparation procedures and the concentration ranges (5-100 μg/g for Pb, 0.5-5 μg/g for As). INAA measured the total content in the sample, while ICP-MS demanded a mineralization procedure resulting in losses/contamination hazards. Thus, INAA results were preferred, although this technique was time consuming. However the ICP-MS results for Cd, Cu, Ni and Pb were retained, for different reasons: detection limits (Cd, Cu), no convenient INAA conditions (Ni), and feasibility (Pb). (authors)