Determination of total cadmium, lead, arsenic, mercury and inorganic arsenic in mushrooms: outcome of IMEP-116 and IMEP-39

The Institute for Reference Materials and Measurements (IRMM) of the Joint Research Centre (JRC), a Directorate General of the European Commission, operates the International Measurement Evaluation Program (IMEP). IMEP organises interlaboratory comparisons (ILCs) in support to European Union (EU) policies. This paper presents the results of two PTs: IMEP-116 and IMEP-39, organised for the determination of total Cd, Pb, As, Hg and inorganic As (iAs) in mushrooms. Participation in IMEP-116 was restricted to National Reference Laboratories (NRLs), while IMEP-39 was open to all other laboratories wishing to participate. Both PTs were organised in support to Regulation (EC) No 1881/2006 which sets the maximum levels for certain contaminants in food. The test item used in both PTs was a blend of mushrooms of the variety shiitake (Lentinula edodes). Five laboratories, with demonstrated measurement capability in the field, provided results to establish the assigned values (Xref). The standard uncertainties associated to the assigned values (uref) were calculated by combining the uncertainty of the characterisation (uchar) with a contribution for homogeneity (ubb) and for stability (ust), whilst uchar was calculated following ISO 13528. Laboratory results were rated with z- and zeta (ζ)-scores in accordance with ISO 13528. The standard deviation for proficiency assessment, σp, for total Pb (20 %) and iAs (19 %) was calculated using the Horwitz equation modified by Thompson. For the other measurands σp was set by the advisory board of the two PTs to 15 % for total As and Hg and to 10 % for total Cd, on the basis of previous performance on similar measurands. Thirty-seven participants from 25 countries reported results in IMEP-116, and 62 laboratories from 36 countries reported for the IMEP-39 study. The percentage of satisfactory z-scores ranged from 81 % (iAs) to 97 % (total Cd) in IMEP-116 and from 64 % (iAs) to 84 % (total Hg) in IMEP-39.JRC.D.5-Standards for Food Bioscienc