Accuracy of a method based on atomic absorption spectrometry to determine inorganic arsenic in food: Outcome of the collaborative trial IMEP-41

A collaborative trial, was conducted in accordance with international protocols to determine the performance characteristics of an analytical method for the quantification of inorganic arsenic (iAs) in food. The method is based on (i) solubilisation of the protein matrix with concentrated hydrochloric acid to denature proteins and allow the release of all arsenic species into solution, and (ii) the subsequent extraction of the inorganic arsenic present in the acid medium using chloroform followed by back-extraction to acid medium. The final detection and quantification is done by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS). Thirteen laboratories, from nine EU countries, registered for participation. All were experienced in the analysis of inorganic arsenic in various food commodities using FI-HG-AAS. The seven test items used in this exercise were all reference materials (either certified reference materials or test items of former IMEP proficiency tests) covering a broad range of matrices and concentrations: mussels tissue (EC-JRC-IRMM, ERM-CE278k), cabbage (IAEA, IAEA-359), seaweed (Hijiki) (NMIJ, CRM 7405a), fish protein (NRC, DORM-4), rice (EC-JRC-IRMM, IMEP-107), wheat (EC-JRC-IRMM, IMEP-112), mushrooms (EC-JRC-IRMM, IMEP-116) and finally rice (EC-JRC-IRMM, ERM-BC211), which was used as pre-test item for training purposes. The mass fraction of iAs was not known for all the test items used, for this reason five laboratories with recognised experience in the analysis of iAs were asked to analyse the test items using a method of their choice, different from the one being validated, in order to compare with the FI-HG-AAS method. The relative standard deviation for repeatability of the validated method (RSDr) ranged from 4.1 to 10.3 %, while the relative standard deviation for reproducibility (RSDR) ranged from 6.1 to 22.8 %. The precision and trueness of the method made it fit-for-the-purpose of determining iAs mass fractions ranging from 0.074 to 7.55 mg kg-1. ; JRC.F.5 - Food ...