Does the determination of inorganic arsenic in rice depend on the method? M.B. de la Calle, H. Emteborg, T.P.J. Linsinger, R. Montoro, J.J. Sloth, R. Rubio, M.J. Baxter, J. Feldmann, P. Vermaercke, G. Raber In answering a request from the Directorate General for Health and Consumers of the European Commission, the European Union Reference Laboratory for Heavy Metals in Feed and Food, with the support of the International Measurement Evaluation Program, organized a proficiency test (PT), IMEP-107, on the determination of total and inorganic arsenic (As) in rice. The main aim of this PT was to judge the state of the art of analytical capability for the determination of total and inorganic As in rice. For this reason, participation in this exercise was open to laboratories from all over the world. Some 98 laboratories reported results for total As and 32 for inorganic As. The main conclusions of IMEP-107 were that the concentration of inorganic As determined in rice does not depend on the analytical method applied and that introduction of a maximum level for inorganic As in rice should not be postponed because of analytical concerns. ª 2011 Elsevier Ltd. All rights reserved. Keywords: Analytical method; Arsenic; Determination; Inorganic arsenic; Proficiency test; Reference value; Rice; Sample homogeneity; Sample stability; Total arsenic 1. Introduction Despite the well-known toxic effects of arsenic (As), there are currently no max- imum limits for total As in European leg- islation for contaminants in foodstuffs. One reason is that As toxicity is strongly related to the chemical species in which it is present (inorganic As is considered more toxic than organic As). Also, seafood, which is the main source of total As in the human diet, contains mainly organic As species. According to the Scientific Opinion on Arsenic in Food, recently released by the European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain [1], the highest total As levels were mea- sured in the following food commodities:  fish and seafood;  products or supplements based on algae (especially hijiki seaweed);  cereals and cereal products, with partic- ularly high concentrations in rice grains, rice-based products, bran and germ. M.B. de la Calle*, H. Emteborg, T.P.J. Linsinger European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg, 111, 2440 Geel, Belgium R. Montoro Metal Contamination Laboratory (IATA-CSIC), Avd. Agustı ´n Escardino 7, 46980 Paterna, Valencia, Spain J.J. Sloth Technical University of Denmark, National Food Institute, Division of Food Chemistry, Mørkhøj Bygade 19, 2860 Søborg, Denmark R. Rubio University of Barcelona, Department of Analytical Chemistry, Martı ´ I Franque `s 1-11, 08028 Barcelona, Spain M.J. Baxter Trace Elements Team, The Food and Environmental Research Agency (Fera), Sand Hutton, York, YO41 1LZ, United Kingdom J. Feldmann Trace Element Speciation Laboratory (TESLA), University of Aberdeen, College of Physical Science, Chemistry, Meston Walk, Aberdeen AB24 3UE, Scotland, United Kingdom P. Vermaercke Belgian Nuclear Research Centre, SCK-CEN, Boeretang 200, 2400 Mol, Belgium G. Raber Institute of Chemistry, Karl-Franzens University Graz, Universita ¨tsplatz 1, 8010 Graz, Austria * Corresponding author. Tel.: +32 (0)14 571252; Fax: +32 (0)14 571863; E-mail: maria.de-la-calle@ec.europa.eu Trends in Analytical Chemistry, Vol. 30, No. 4, 2011 Trends 0165-9936/$ - see front matter ª 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.trac.2010.11.015 641