Assessment of the ICP-MS method using the interlaboratory QA study of two Polish soil RMs

Under an international collaborative certification programme, two new Polis h soil reference materials, PL-1 (loess) and BPGM-1 (sandy loam soil), were analysed for 34 trace elements including all the rare earth elements using the acid decomposition method and inductively coupled plasma - mass spectr ometry (ICP-MS). After the certification by the organisers, the analytical data obtained at our institute were compared with the certified data. 'Z-sc ore' values calculated for individual trace elements helped in the assessme nt of the quality of the data. While the majority of the data obtained on I CP-MS was very precise and accurate, some of the data especially for elemen ts such as Zr, Hf and Nb suffered from incomplete dissolution of the sample and spectroscopic interferences. For some trace elements, certified data a re not available for comparison. These features together with the usefulnes s of interlaboratory collaborative programmes and ICP-MS for the certificat ion of soil reference materials are discussed.